Статті в журналах: "TIME-RESOLVED PHOTOLUMINESCENCE (TRPL)"

1

OHNO, N., and X. M. WEN. "TIME-RESOLVED PHOTOLUMINESCENCE OF EXCITONS IN HgI2." International Journal of Modern Physics B 15, no. 28n30 (December 10, 2001): 3920–23. http://dx.doi.org/10.1142/s0217979201009001.

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The time-resolved photoluminescence (TRPL) of red HgI 2 single crystal has been measured to determine the carrier lifetimes and to reveal the energy relaxation of excitons. Sharp near-bandgap luminescence lines due to free and bound excitons are observed at 530 nm, and a broad luminescence band appears at 630 nm at low temperatures. TRPL experiments of the near-bandgap luminescence have revealed that the luminescence comprise fast (30 to 200 ps) and slow (100 to 400 ps) decay components, showing several relaxation processes in free and bound exciton annihilation. TRPL of the broad band at 630 nm has shown that the luminescence is ascribed to the radiative recombination of donor-acceptor (DA) pairs.

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2

Péan, Emmanuel V., Stoichko Dimitrov, Catherine S. De Castro, and Matthew L. Davies. "Interpreting time-resolved photoluminescence of perovskite materials." Physical Chemistry Chemical Physics 22, no. 48 (2020): 28345–58. http://dx.doi.org/10.1039/d0cp04950f.

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3

Chen, Cheng, Zhi Ren Qiu, Xiang Ping Shu, Zeng Cheng Li, Jian Ping Liu, and Zhe Chuan Feng. "Temperature and Time-Resolved Dependence of Photoluminescence in InGaN Quantum Dots." Advanced Materials Research 750-752 (August 2013): 927–30. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.927.

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Temperature dependence of photoluminescence (PL) and time resolved photoluminescence (TRPL) were obtained by two experimental systems. The relative intensity and peak position of PL show S-shift variation with increasing temperature, which may result from temperature induce carriers redistribution. Fast decay time and slow decay time were fitted by double exponential function from decay curves of TRPL at different emission energy, and the decreasing trend of both fast decay and slow decay time with increasing photon energy is attributed to various channels of recombination in shallow and deep localized states.

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4

WRABACK, MICHAEL, GREGORY A. GARRETT, ANAND V. SAMPATH, and PAUL H. SHEN. "UNDERSTANDING ULTRAVIOLET EMITTER PERFORMANCE USING INTENSITY DEPENDENT TIME-RESOLVED PHOTOLUMINESCENCE." International Journal of High Speed Electronics and Systems 17, no. 01 (March 2007): 179–88. http://dx.doi.org/10.1142/s0129156407004400.

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Time-resolved photoluminescence studies of nitride semiconductors and ultraviolet light emitters comprised of these materials are performed as a function of pump intensity as a means of understanding and evaluating device performance. Comparison of time-resolved photoluminescence (TRPL) on UV LED wafers prior to fabrication with subsequent device testing indicate that the best performance is attained from active regions that exhibit both reduced nonradiative recombination due to saturation of traps associated with point and extended defects and concomitant lowering of radiative lifetime with increasing carrier density. Similar behavior is observed in optically pumped UV lasers. Temperature and intensity dependent TRPL measurements on a new material, AlGaN containing nanoscale compositional inhomogeneities (NCI), show that it inherently combines inhibition of nonradiative recombination with reduction of radiative lifetime, providing a potentially higher efficiency UV emitter active region.

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5

Yuan, Long, and Libai Huang. "Exciton dynamics and annihilation in WS2 2D semiconductors." Nanoscale 7, no. 16 (2015): 7402–8. http://dx.doi.org/10.1039/c5nr00383k.

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6

Tsai, Ming Kwen, Yueh Chien Lee, Chia Chih Huang, Sheng Yao Hu, Kwong Kau Tiong, and Bo Yao Hong. "Luminescence Mechanism of ZnWO₄ Nanopowder Synthesized by Microwave-Assisted Heating." Applied Mechanics and Materials 470 (December 2013): 44–47. http://dx.doi.org/10.4028/www.scientific.net/amm.470.44.

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The luminescence investigations on the calcinated zinc tungstate nanopowder (ZnWO4 NP) synthesized by microwave-assisted synthesis are presented using photoluminescence (PL) and time-resolved photoluminescence (TRPL) analyses. The X-ray diffraction (XRD) patterns exhibit that the significant wolframite structure of ZnWO4 NP can be detected at calcination temperatures above 300 °C. The 12 K PL and TRPL results demonstrated that the deformation of WO6 octahedra is responsible for the low-energy side of PL spectra and dominate the red-shifted PL spectra with increasing calcination temperatures.

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7

Yi, Jun, Xueying Ge, Exian Liu, Tong Cai, Chujun Zhao, Shuangchun Wen, Hugo Sanabria, Ou Chen, Apparao M. Rao, and Jianbo Gao. "The correlation between phase transition and photoluminescence properties of CsPbX3 (X = Cl, Br, I) perovskite nanocrystals." Nanoscale Advances 2, no. 10 (2020): 4390–94. http://dx.doi.org/10.1039/d0na00545b.

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We report a correlation between the structural phase transition of CsPbX₃ (X = Cl, Br, I) nanocrystals (NCs) and their temperature dependent steady-state photoluminescence (PL) and time-resolved PL (TRPL).

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8

Lai, Fang-I., Jui-Fu Yang, Wei-Chun Chen, Dan-Hua Hsieh, Woei-Tyng Lin, Yu-Chao Hsu, and Shou-Yi Kuo. "Energy-Dependent Time-Resolved Photoluminescence of Self-Catalyzed InN Nanocolumns." Catalysts 11, no. 6 (June 16, 2021): 737. http://dx.doi.org/10.3390/catal11060737.

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In this study, we report the optical properties and carrier dynamics of different surface dimensionality n-type wurtzite InN with various carrier concentrations using photoluminescence (PL) and an energy-dependent, time-resolved photoluminescence (ED-TRPL) analysis. Experimental results indicated that the InN morphology can be controlled by the growth temperature, from one-dimensional (1D) nanorods to two-dimensional (2D) films. Moreover, donor-like nitrogen vacancy (VN) is responsible for the increase in carrier concentration due to the lowest formation energies in the n-type InN samples. The PL results also reveal that the energies of emission peaks are higher in the InN samples with 2D features than that with 1D features. These anomalous transitions are explained as the recombination of Mahan excitons and localized holes, and further proved by a theoretical model, activation energy and photon energy-dependent lifetime analysis.

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9

Xiao, Zijie, Tingting Tao, Jingting Shu, Wei Dang, Shusheng Pan, and Wei Zhang. "Charge Carrier Recombination Dynamics in MAPb(Br1−yIy)3 Single Crystals." Crystals 12, no. 10 (October 9, 2022): 1425. http://dx.doi.org/10.3390/cryst12101425.

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Studying the carrier recombination process in MAPb(Br1−yIy)3 single crystals (SCs) is important for its application in the optoelectronic field. In this work, a series of MAPb(Br1−yIy)3 SCs with varied Br/I compositions have been studied. Steady-state photoluminescence (PL) spectra, time-resolved photoluminescence (TRPL) spectra and time-resolved microwave photoconductivity (TRMC) were used to understand the radiative and non-radiative recombination processes of MAPb(Br1−yIy)3 SCs. By comparing the dynamics of TRPL and TRMC, we conclude that the dynamics of TRPL is dominated by the electron trapping process, which is in accordance with the fast decay component of TRMC kinetics, whereas the slower decay component in TRMC is dominated by the hole trapping process. Moreover, we find both the electron and hole trapping rates in mixed-halide perovskite MAPb(Br1−yIy)3 (0 < y < 1) SCs are higher than that of mono-halide perovskite MAPbBr3 SCs and MAPbI3 SCs. This suggests mixed-halide crystals could introduce additional electron and hole trapping densities, which could be related to the fluctuation of Br/I compositions in the crystals. This work is helpful for understanding carrier recombination process in mixed-halide perovskite SCs.

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10

Kuo, Ting Wei, Ling Min Kong, Zhe Chuan Feng, Wei Liu, Soo Jin Chua, and Ying Sheng Huang. "Photoluminescence Properties of InGaN/GaN Multiple Quantum Well Light Emitting Diodes by Metalorganic Chemical Vapor Deposition." Advanced Materials Research 306-307 (August 2011): 1133–37. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.1133.

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Luminescence properties of blue emission InGaN/GaN multiple quantum well (MQW) light emitting diodes (LEDs), grown on sapphire substrates by metal organic chemical vapor deposition (MOCVD), were studied by time-resolved photoluminescence (TRPL) spectroscopic technique. Samples involved have similar basic structures of three QWs but different well-composition and barrier/well dimensions. TRPL results show that PL intensity and decay time increase with the number of QWs and the indium composition. Correlation of physical properties with crystalline perfection open the way for optimized designs of InGaN MQW LED, with controlled the indium composition and QW numbers.

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11

KUMAR, DHIRAJ, SUNIL KUMAR, and H. S. BHATTI. "LASER-INDUCED PHOTOLUMINESCENT STUDIES OF Al-DOPED ZINC OXIDE NANOPARTICLES." International Journal of Nanoscience 09, no. 05 (October 2010): 439–45. http://dx.doi.org/10.1142/s0219581x10007101.

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In this paper, addition of aluminum in zinc oxide is incorporated using low-temperature chemical synthesis route. Aluminum ions help in crystallization of zinc oxide nanoparticles. Characterization of the synthesized nanoparticles of zinc oxide has been done using Transmission electron microscope (TEM), and X-ray diffraction (XRD) analysis, Energy-resolved photoluminescence (PL) spectra and Time-resolved laser-induced photoluminescence (TRPL) at room temperature. Transmission electron microscopic observations and X-Ray diffraction studies indicate highly crystalline nature and particle size of the order of 20 nm in ZnO:Al . Time-resolved laser-induced photoluminescence measurements have been done using pulsed nitrogen laser as an excitation source, operated at wavelength 337.1 nm and having high peak output power of 1 MW. The results show that at higher concentrations of Al doping in host ZnO phosphor, emission intensity is more by several orders of magnitude and lifetime shortening indicates that these nanoparticles are more efficient as compared with lower concentrations of dopant.

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12

Putro, Permono Adi, Liszulfah Roza, and Isnaeni Isnaeni. "THE EFFECT OF POLY (ETHYLENE GLYCOL) ON THE PHOTOLUMINESCENCE PROPERTIES OF CARBON DOTS FROM CASSAVA PEELS SYNTHESIZED BY HYDROTHERMAL METHODS." Spektra: Jurnal Fisika dan Aplikasinya 4, no. 1 (April 30, 2019): 11–20. http://dx.doi.org/10.21009/spektra.041.02.

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Carbon dots (C-dots) have been successfully synthesized from cassava peels using the hydrothermal method. The C-dots are further passivated using poly (ethylene glycol) (PEG) with a variation of the volume of 0.5 ml, 1.0 ml, and 1.5 ml. The properties of photoluminescence C-dots before and after PEG were characterized using photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectrophotometers. PEG succeeded in influencing PL C-dots properties, such as peak wavelength, PL intensity, and electron time decay. The addition of 0.5 ml of PEG to C-dots is the optimum condition and best with the peak wavelength, the PL intensity and, time decay electron is 507.52 nm, 5302 a.u, and 3.794031133 ns, respectively.

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13

Beyer, Jan, Nadine Schüler, Jürgen Erlekampf, Birgit Kallinger, Patrick Berwian, Kay Dornich, and Johannes Heitmann. "Minority Carrier Lifetime Measurements on 4H-SiC Epiwafers by Time-Resolved Photoluminescence and Microwave Detected Photoconductivity." Materials Science Forum 963 (July 2019): 313–17. http://dx.doi.org/10.4028/www.scientific.net/msf.963.313.

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Temperature dependent microwave detected photoconductivity MDP and time-resolved photoluminescence TRPL were employed to investigate the carrier lifetime in CVD grown 4H-SiC epilayers of different thickness. The minority carrier lifetime may be found from both theMDP and defect PL decay at room temperature for all epilayers, whereas the near bandedge emission (NBE) decay is much faster for thin epilayers (<17 μm) due to the substrate proximity and only follows the minority carrier lifetime for thicker samples at lower excess carrier concentrations.

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14

Wei, Yi, Ahmed Fadil, and Hai Yan Ou. "Localized Surface Plasmon on 6H SiC with Ag Nanoparticles." Materials Science Forum 897 (May 2017): 634–37. http://dx.doi.org/10.4028/www.scientific.net/msf.897.634.

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Silver (Ag) nanoparticles (NPs) were deposited on the surface of bulk Nitrogen-Boron co-doped 6H silicon carbide (SiC), and the Ag NPs were observed to induce localized surface plasmons (LSP) resonances on the SiC substrate, which was expected to improve the internal quantum efficiency (IQE) of the emissions of the donor-acceptor pairs of the SiC substrate. Room-temperature measurements of photoluminescence (PL), transmittance and time-resolved photoluminescence (TRPL) were applied to characterize the LSP resonances. Through the finite-difference time-domain (FDTD) simulation of the LSP resonance of an Ag nanoparticle on the SiC substrate, it is predicted that when the diameter of the cross section on the xy plane of the Ag nanoparticle is greater than 225 nm, the LSP starts to enhance the PL intensity. With implementation of a 3rd order exponential decay fitting model to the TRPL results, it is found that the average minority carrier lifetime of the SiC substrate decreased.

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15

Holewa, Paweł, Jakub Jasiński, Artem Shikin, Elizaveta Lebedkina, Aleksander Maryński, Marcin Syperek, and Elizaveta Semenova. "Optical Properties of Site-Selectively Grown InAs/InP Quantum Dots with Predefined Positioning by Block Copolymer Lithography." Materials 14, no. 2 (January 14, 2021): 391. http://dx.doi.org/10.3390/ma14020391.

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The InAs/InP quantum dots (QDs) are investigated by time-integrated (PL) and time-resolved photoluminescence (TRPL) experiments. The QDs are fabricated site-selectively by droplet epitaxy technique using block copolymer lithography. The estimated QDs surface density is ∼1.5 × 1010 cm−2. The PL emission at T=300 K is centered at 1.5 μm. Below T=250 K, the PL spectrum shows a fine structure consisting of emission modes attributed to the multimodal QDs size distribution. Temperature-dependent PL reveals negligible carrier transfer among QDs, suggesting good carrier confinement confirmed by theoretical calculations and the TRPL experiment. The PL intensity quench and related energies imply the presence of carrier losses among InP barrier states before carrier capture by QD states. The TRPL experiment highlighted the role of the carrier reservoir in InP. The elongation of PL rise time with temperature imply inefficient carrier capture from the reservoir to QDs. The TRPL experiment at T=15 K reveals the existence of two PL decay components with strong dispersion across the emission spectrum. The decay times dispersion is attributed to different electron-hole confinement regimes for the studied QDs within their broad distribution affected by the size and chemical content inhomogeneities.

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16

Karhu, Robin, Ian Booker, Ivan G. Ivanov, Erik Janzén, and Jawad ul Hassan. "Long Charge Carrier Lifetime in As-Grown 4H-SiC Epilayer." Materials Science Forum 858 (May 2016): 125–28. http://dx.doi.org/10.4028/www.scientific.net/msf.858.125.

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Over 150 μm thick epilayers of 4H-SiC with long carrier lifetime have been grown with a chlorinated growth process. The carrier lifetime have been determined by time resolved photoluminescence (TRPL), the lifetime varies a lot between different areas of the sample. This study investigates the origins of lifetime variations in different regions using deep level transient spectroscopy (DLTS), low temperature photoluminescence (LTPL) and a combination of KOH etching and optical microscopy. From optical microscope images it is shown that the area with the shortest carrier lifetime corresponds to an area with high density of structural defects.

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17

Lee, Zhen Sheng, Ling Min Kong, Zhe Chuan Feng, Gang Li, Hung Lin Tsai, and Jer Ren Yang. "Luminescence Dynamics and Structural Investigation of InGaN/GaN Multiple Quantum Well Light Emitting Diodes." Advanced Materials Research 216 (March 2011): 445–49. http://dx.doi.org/10.4028/www.scientific.net/amr.216.445.

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Luminescence properties of blue emission InGaN/GaN multiple quantum well (MQW) have been studied by temperature dependent photoluminescence (PL), photoluminescence excitation (PLE) and time-resolved photoluminescence (TRPL) spectroscopic techniques. Two typical samples are studied, both consisting of five periods of InGaN wells with different indium compositions of 21% and 24%, respectively. According to the PL and PLE measurement results, large values of activation energy and Stokes’ shift are obtained. This indicates that higher Indium composition results in an increase of composition fluctuation in the InGaN MQW region, showing the stronger carrier localization effect. The lifetime at the low-energy side of the InGaN peaks is longer for higher indium composition, as expected from the larger Stokes shift.

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18

WACHTER, S., DAL DON, M. BALDAUF, M. SCHMIDT, E. KURTZ, C. KLINGSHIRN, H. KALT, D. LITVINOV, and D. GERTHSEN. "INTER - ISLAND TRANSPORT IN CdSe/ZnSe QUANTUM HETEROSTRUCTURES." International Journal of Modern Physics B 15, no. 28n30 (December 10, 2001): 3584–87. http://dx.doi.org/10.1142/s0217979201008202.

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We report on localization dynamics of excitons in ensembles of self–organized CdSe islands embedded in ZnSe. The experimental methods employed are temperature–dependent, spatially resolved photoluminescence (μ–PL), spatially integrated PL (macro-PL), as well as time–resolved PL (TRPL). We observe the well known non–monotonous shift of the PL maximum with temperature caused by redistribution of the excitons amongst the islands. The measured shift is compared with the exact shift of the bandgap deduced from μ–PL measurements and found to depend strongly on island size and distribution. These transport processes are recovered in the temporal evolution of the PL. The decaytime of the spectrally integrated PL reaches its maximum at exactly the same temperature at which the redhift of the macro–PL turns into a blueshift. In TRPL the PL–spectrum consists of two contributions. We put the emission on the high energy side down to excited states in the islands.

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19

Strak, Pawel, Kamil Koronski, Konrad Sakowski, Kamil Sobczak, Jolanta Borysiuk, Krzysztof P. Korona, Piotr A. Dróżdż, et al. "Instantaneous decay rate analysis of time resolved photoluminescence (TRPL): Application to nitrides and nitride structures." Journal of Alloys and Compounds 823 (May 2020): 153791. http://dx.doi.org/10.1016/j.jallcom.2020.153791.

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20

Gandan, Shumithira, Lucas L. G. Pinel, Juan S. D. Morales, Jo Shien Ng, Chee Hing Tan, and Tomasz Ochalski. "Recombination processes in MBE grown Al_0.85Ga_0.15As_0.56Sb_0.44." AIP Advances 13, no. 4 (April 1, 2023): 045010. http://dx.doi.org/10.1063/5.0145051.

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Quaternary AlGaAsSb alloys have exhibited low excess noise characteristics as gain regions in avalanche photodiodes. In this work, optical spectroscopy techniques are used to demonstrate the recombination dynamics in molecular beam epitaxy grown Al0.85Ga0.15As0.56Sb0.44 with temperature variation. Photoluminescence (PL) measurements at 8–50 K show that the bandgap varies from 1.547 to 1.527 eV. The radiative recombination processes in the alloy were found to be dictated by the complexities of antimony (Sb) incorporation during the growth. Time-resolved PL (TRPL) measurements show a change in initial carrier lifetimes of ∼3.5 µs at 8 K to ∼1 µs at 30 K. The knowledge of carrier dynamics from optical characterization methods such as PL and TRPL can be employed to contribute to shorter feedback loops for improvement of alloy fabrication in addition to enhancing growth processes.

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21

WENG, GUO-EN, BAO-PING ZHANG, MING-MING LIANG, XUE-QIN LV, JIANG-YONG ZHANG, LEI-YING YING, ZHI REN QIU, et al. "OPTICAL PROPERTIES AND CARRIER DYNAMICS IN ASYMMETRIC COUPLED InGaN MULTIPLE QUANTUM WELLS." Functional Materials Letters 06, no. 02 (April 2013): 1350021. http://dx.doi.org/10.1142/s1793604713500215.

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Optical properties and carrier dynamics of InGaN/GaN asymmetric coupled quantum wells (ACQWs) are studied by excitation-power-dependent photoluminescence (PL), photoreflectance (PR) and time-resolved PL (TRPL) experiments. Under weak excitations, only the emission from the widest well is observed due to the tunneling from narrower to wider wells. Under strong excitations, the carrier distribution becomes more uniform and an enhanced emission from the mid well (2.5 nm well) is observed. Dependence of the PL intensity on excitation power is well explained by a rate equation model. The energy levels in the ACQW structure are clearly revealed by PR measurements and are in good agreement with calculations. Our results indicate that the enhanced emission from the mid well is ascribed to "reverse tunneling" from 3.0 to 2.5 nm well, which is confirmed by TRPL experiments.

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22

Mahadik, Nadeemullah A., Robert E. Stahlbush, Paul B. Klein, Ani Khachatrian, and Stephen Buchner. "Depth Profiling of Carrier Lifetime in Thick 4H-SiC Epilayers Using Two-Photon Absorption." Materials Science Forum 924 (June 2018): 265–68. http://dx.doi.org/10.4028/www.scientific.net/msf.924.265.

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Depth profiling of the ambipolar carrier lifetime was performed in n-type, 140mm thick silicon carbide (SiC) epilayer using excitation by two-photon absorption (TPA) with a pulsed 586nm laser, and confocal measurement of time resolved photoluminescence (TRPL) decay from the excited region. A depth resolution of ≈10mm was obtained. The PL decay curves were analyzed using a recently developed formalism that takes into account the TPA excitation, carrier diffusion and surface/interface recombination. The carrier lifetime decreases near the top surface of the epitaxial layer as well as near its interface with the substrate.

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23

Buschmann, Volker, Eugeny Ermilov, Felix Koberling, Maria Loidolt-Krüger, Jürgen Breitlow, Hugo Kooiman, Johannes W. N. Los, et al. "Integration of a superconducting nanowire single-photon detector into a confocal microscope for time-resolved photoluminescence (TRPL)-mapping: Sensitivity and time resolution." Review of Scientific Instruments 94, no. 3 (March 1, 2023): 033703. http://dx.doi.org/10.1063/5.0134451.

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This report highlights the combination of the MicroTime 100 upright confocal fluorescence lifetime microscope with a Single Quantum Eos Superconducting Nanowire Single-Photon Detector (SNSPD) system as a powerful tool for photophysical research and applications. We focus on an application in materials science, photoluminescence imaging, and lifetime characterization of Cu(InGa)Se2 (CIGS) devices intended for solar cells. We demonstrate improved sensitivity, signal-to-noise ratio, and time-resolution in combination with confocal spatial resolution in the near-infrared (NIR) range, specifically in the 1000–1300 nm range. The MicroTime 100–Single Quantum Eos system shows two orders of magnitude higher signal-to-noise ratio for CIGS devices' photoluminescence imaging compared to a standard NIR-photomultiplier tube (NIR-PMT) and a three-fold improvement in time resolution, which is now limited by the laser pulse width. Our results demonstrate the advantages in terms of image quality and time resolution of SNSPDs technology for imaging in materials science.

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24

Sönmez, Erdal, and Kadem Meral. "Enhancement of Photoluminescence Lifetime of ZnO Nanorods Making Use of Thiourea." Journal of Nanomaterials 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/957035.

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We have investigated correlation of photoluminescence lifetime between zinc oxide (ZnO) nanorods and thiourea-doped ZnO nanorods (tu: CH4N2S). Aqueous solutions of ZnO nanorods were deposited on glass substrate by using pneumatic spray pyrolysis technique. The as-prepared specimens were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and time-resolved photoluminescence spectroscopy (TRPL). The photoluminescence lifetime of ZnO nanorods and ZnO nanorods containing thiourea was determined as ns and ns , respectively. The calculated lifetime values of ZnO nanorods revealed that the presence of thiourea in ZnO nanorods resulted in increasing the exciton lifetime. In addition to the optical quality of ZnO nanorods, their exciton lifetime is comparable to the longest lifetimes reported for ZnO nanorods. The structural improvement of ZnO nanorods, containing thiourea, was also elucidated by taking their SEM images which show the thinner and longer ZnO nanorods compared to those without thiourea.

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25

Žurauskienė, N., S. Ašmontas, A. Dargys, J. Kundrotas, G. Janssen, E. Goovaerts, Stanislovas Marcinkevičius, Paul M. Koenraad, J. H. Wolter, and R. P. Leon. "Semiconductor Nanostructures for Infrared Applications." Solid State Phenomena 99-100 (July 2004): 99–108. http://dx.doi.org/10.4028/www.scientific.net/ssp.99-100.99.

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We present the results of time-resolved photoluminescence (TRPL) and optically detected microwave resonance (ODMR) spectroscopy investigations of semiconductor quantum dots and quantum wells. The ODMR spectra of InAs/GaAs QDs were detected via modulation of the total intensity of the QDs emission induced by 95 GHz microwave excitation and exciton fine structure was studied. Very long life times (up to 10 ns) of photoexcited carriers were observed in this system using TRPL at low temperatures and excitation intensities promising higher responsitivity of such QDs for quantum dot infrared photodetector development. The effects of proton and alpha particles irradiation on carrier dynamics were investigated on different InGaAs/GaAs, InAlAs/AlGaAs and GaAs/AlGaAs QD and QW systems. The obtained results demonstrated that carrier lifetimes in the QDs are much less affected by proton irradiation than that in QWs. A strong influence of irradiation on the PL intensity was observed in multiple QWs after high-energy alpha particles irradiation.

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26

Song, Yue, Yongyi Chen, Ligong Zhang, Yugang Zeng, Cheng Qiu, Lei Liang, Yuxin Lei, et al. "Carrier Dynamic Investigations of AlGaInAs Quantum Well Revealed by Temperature-Dependent Time-Resolved Photoluminescence." Materials 13, no. 19 (September 23, 2020): 4227. http://dx.doi.org/10.3390/ma13194227.

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AlGaInAs quantum well (QW) lasers have great potential in the application fields of optical communications and eye-safety lidars, owing to the advantages of good gain performance. A large amount of experimental evidence indicated that carrier dynamic affects the resonant frequency and modulation response performance of QW lasers. However, the mechanism of carrier dynamic in AlGaInAs QW structure is still ambiguous for complicated artificial multilayers. In this paper, the carrier dynamic of AlGaInAs QW structure was investigated by temperature-dependent time-resolved photoluminescence (TRPL) in the range of 14 to 300 K. Two relaxation times (a fast component and a slow one) have a major impact on the PL emission spectra of the AlGaInAs QW below 200 K. The carriers prefer a fast decay channel in the low temperature regime, whereas the slow one a higher temperature. An unconventional temperature dependence of carrier relaxation is observed in both decay processes. The carriers’ lifetime decreases with the temperature increasing till 45 K and then increases with temperature up to 250 K. It is quite different from that in the bulk semiconductor. The mechanism of temperature-dependent carrier relaxation at temperatures above 45 K is a combination of dark state occupation and a nonradiative recombination process.

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27

Putro, Permono Adi, Liszulfah Roza, and Isnaeni Isnaeni. "Photoluminescence Properties of Poly (Ethylene Glycol) Passivated Carbon Dots from Cassava Peels." Indonesian Journal of Science and Education 3, no. 2 (October 29, 2019): 76. http://dx.doi.org/10.31002/ijose.v3i2.1209.

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Carbon dots (C-dots) is a new type of luminescense nanoparticles that can be synthesized easily from natural sources, such as cassava peels. C-dots has been synthesized from cassava peels based green synthesis using low temperature. The surface of C-dots was passivated by poly(ethylene glycol) (PEG) with variations in volume from 0.5 ml, 1 ml, and 1.5 ml. Luminescense properties before and after passivasive with PEG characterized using photoluminescense (PL) and time resolved photoluminescence (TRPL) spectrophotometer. Peak wavelength spectrum of PL shows a red shift when 0.5 ml PEG was added. However, when the addition of PEG increases, peak wavelength spectrum of PL shows a blue shift. PL intensity decreased along with increasing of PEG volume. PL intensity influenced C-dots electron time decay linearly. C-dots electron time decay increased along with decreased of PL intensity. This results assigned potency that C-dots in water solution can be applied as bioimaging and metal ion and salt biosensing. however, it needs extra optical measurements to support our discovery.Keywords: cassava peels, C-dots, electron time decay, FL intensity, PEG

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28

Krajewski, Maciej, Piotr Piotrowski, Wojciech Mech, Krzysztof P. Korona, Jacek Wojtkiewicz, Marek Pilch, Andrzej Kaim, Aneta Drabińska, and Maria Kamińska. "Optical Properties and Light-Induced Charge Transfer in Selected Aromatic C60 Fullerene Derivatives and in Their Bulk Heterojunctions with Poly(3-Hexylthiophene)." Materials 15, no. 19 (October 5, 2022): 6908. http://dx.doi.org/10.3390/ma15196908.

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Fullerene derivatives offer great scope for modification of the basic molecule, often called a buckyball. In recent years, they have been the subject of numerous studies, in particular in terms of their applications, including in solar cells. Here, the properties of four recently synthesized fullerene C60 derivatives were examined regarding their optical properties and the efficiency of the charge transfer process, both in fullerene derivatives themselves and in their heterojunctions with poly (3-hexylthiophene). Optical absorption, electron spin resonance (ESR), and time-resolved photoluminescence (TRPL) techniques were applied to study the synthesized molecules. It was shown that the absorption processes in fullerene derivatives are dominated by absorption of the fullerene cage and do not significantly depend on the type of the derivative. It was also found by ESR and TRPL studies that asymmetrical, dipole-like derivatives exhibit stronger light-induced charge transfer properties than their symmetrical counterparts. The observed inhomogeneous broadening of the ESR lines indicated a large disorder of all polymer–fullerene derivative blends. The density functional theory was applied to explain the results of the optical absorption experiments.

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29

Ramlan, Nurul Mutmainnah, Arini Qurrata A'yun, Radha Hartina Putri, Siti Fatimah, Isnaeni, and Dahlang Tahir. "Analysis Optical Properties of Carbon Dots from Paper Flowers (Bougainvillea spectabilis)." Omega: Jurnal Fisika dan Pendidikan Fisika 4, no. 2 (November 30, 2018): 30. http://dx.doi.org/10.31758/omegajphysphyseduc.v4i2.30.

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Synthesized carbon dots (CDs) from paper flowers (Bougainvillea spectabilis) was performed by microwave assisted. CDs were characterized by ultraviolet visible light (UV-Vis), photoluminescence (PL) and time resolved luminescence (TRPL). PL data shows wavelength intensity of CDs paper flowers at 493 nm for 3.9 ns and 512 nm for 4.2 ns respectively for purple and white paper flowers that excited at 420 nm. The absorbance for CDs white paper flower at 262 nm and 350 nm, while CDs purple flower paper at 260 nm, 324 nm, and 530 nm. CDs from paper flower shows excellent optical properties. So, it is mean that method applied to this experiment effectively, cheap and eco-friendly for synthesis CDs from paper flower.

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30

Kumar, Narender, Vijo Poulose, Youssef Taiser Laz, Falguni Chandra, Salma Abubakar, Abdalla S. Abdelhamid, Ahmed Alzamly, and Na’il Saleh. "Temperature Control of Yellow Photoluminescence from SiO2-Coated ZnO Nanocrystals." Nanomaterials 12, no. 19 (September 27, 2022): 3368. http://dx.doi.org/10.3390/nano12193368.

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In this study, we aimed to elucidate the effects of temperature on the photoluminescence from ZnO–SiO2 nanocomposite and to describe the preparation of SiO2-coated ZnO nanocrystals using a chemical precipitation method, as confirmed by Fourier transform infrared (FTIR) and powder X-ray diffraction analysis (XRD) techniques. Analyses using high-resolution transmission microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), and electrophoretic light scattering (ELS) techniques showed that the new nanocomposite has an average size of 70 nm and 90% silica. Diffuse reflectance spectroscopy (DRS), photoluminescence (PL), and photoluminescence-excitation (PLE) measurements at different temperatures revealed two emission bands at 385 and 590 nm when the nanomaterials were excited at 325 nm. The UV and yellow emission bands were attributed to the radiative recombination and surface defects. The variable-temperature, time-resolved photoluminescence (VT-TRPL) measurements in the presence of SiO2 revealed the increase in the exciton lifetime values and the interplay of the thermally induced nonradiative recombination transfer of the excited-state population of the yellow emission via deep centers (DC). The results pave the way for more applications in photocatalysis and biomedical technology.

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31

Zhao, Xinwei, Ting Zheng, Weiwei Zhao, Yuanfang Yu, Wenhui Wang, and Zhenhua Ni. "Photoluminescence Modulation of Ruddlesden-Popper Perovskite via Phase Distribution Regulation." Nanomaterials 13, no. 3 (January 31, 2023): 571. http://dx.doi.org/10.3390/nano13030571.

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The intrinsic chaotic phase distribution in Ruddlesden-Popper Perovskite (RPP) hinders its further improvement of photoluminescence (PL) emission and limits its application in optical devices. In this work, we achieve the phase distribution regulation of RPP by varying the composition ratio of organic bulky spacer cations 1-naphthylmethylamine (NMA) and phenylethyl-ammonium (PEA), which is controllable and nondestructive for structures of RPP. By suppressing the small n-phase, the PL intensity emission of RPP is further improved. Through the time-resolved PL (TRPL) measurements, we find the PL lifetime of the sample with 66% PEA concentration increases with the temperature initially and possesses the highest values of τ1 and τ2 at ~255 K, indicating the immediate state assisting exciton radiative recombination, and it can be modulated by phase manipulation in RPP. The immediate state may outcompete other non-radiative decay channels for excited carriers, leading to the PL enhancement in RPP, and broadening its further application.

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32

Mohapatra, M., V. Natarajan, and S. V. Godbole. "Speciation of ‘Eu’ in sol–gel derived alkali barium borosilicate glass: Time resolved photoluminescence (TRPL) and Judd—Ofelt analysis." Journal of Non-Crystalline Solids 386 (February 2014): 115–20. http://dx.doi.org/10.1016/j.jnoncrysol.2013.12.002.

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33

Shao, Zhufeng, Hui Jia, Yufeng Zhang, Xiujuan Yang, Min Zhong, and Chun Chang. "Oxygen Vacancy-Mediated Interfacial Charge Transfer of Au/ZnO Schottky Heterojunctions for Enhanced UV Photodegradation." International Journal of Photoenergy 2020 (July 7, 2020): 1–17. http://dx.doi.org/10.1155/2020/2456968.

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We intend to report an interesting phenomenon related to the different interfacial transfer processes between ellipsoidal-like ZnO (E-ZnO) and rod-like ZnO (R-ZnO) nanoheterojunctions witness by the nanosecond time-resolved transient photoluminescence (NTRT-PL) spectra. Fristly, E-ZnO and R-ZnO nanoarchitectures were fabricated via facilitating the electrochemical route; and then, they decorated it with dispersed Au nanoparticles (NPs) by the methods of ion-sputtering deposition, constituting Au/E-ZnO and Au/R-ZnO Schottky-heterojunction nanocomplex, which is characterized by SEM, XRD, Raman analysis, and UV-vis absorption spectra. Steady-state photoluminescence and NTRT-PL spectra of as-fabricated Au/E-ZnO and Au/R-ZnO nanocomposites were probed for interfacial charge transfer process under 266 nm femtosecond (fs) light irradiation. Simultaneously, a distinct diversification for the NTRT-PL spectra is observed, closely associating with oxygen vacancies (Vo), which is confirmed by X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) spectra. Furthermore, Au NPs act as an “annular bridge” and “transit depot” for interfacial charge transfer through local surface plasmon resonance (LSPR) effect and Schottky barrier, respectively, which is identified by NTRT-PL and time-resolved PL (TRPL) decay spectrum. Moreover, this mechanism is responsible for the enhanced photoelectrochemical (PEC) performances of methyl orange (MO) photodegradation under UV light irradiation.

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34

Thawarkar, Sachin, Sachin R. Rondiya, Prem Jyoti Singh Rana, Ramanuj Narayan, Nelson Y. Dzade, and Surya Prakash Singh. "Structural and optical properties of ionic liquid-based hybrid perovskitoid: A combined experimental and theoretical investigation." Functional Materials Letters 14, no. 04 (April 27, 2021): 2150008. http://dx.doi.org/10.1142/s1793604721500089.

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Herein, we report a novel layered lead bromide, (CH3CH[Formula: see text]N[Formula: see text]Br[Formula: see text](CH[Formula: see text]NH[Formula: see text]PbBr3, where bulky organic cations, (CH3CH[Formula: see text]N[Formula: see text]Br[Formula: see text](CH[Formula: see text]NH[Formula: see text], amino-ethyl triethyl ammonium [aetriea] were not only incorporated between the inorganic layers but also sandwiched within the inorganic [PbBr6][Formula: see text] octahedral layered structure. The UV-Visible, photoluminescence spectroscopy (PL), X-ray diffraction (XRD) and a field-emission scanning electron microscope (FE-SEM) result show that the new perovskitoid has a microrod shape with an estimated bandgap of [Formula: see text]3.05 eV. The structural and optoelectronic properties of the [aetriea]PbBr3perovskitoid were further corroborated by first-principles density functional theory (DFT) calculations. Thermogravimetric analysis (TGA) data show good stability of the [aetriea]PbBr3perovskitoid. Time-resolved photoluminescence (TRPL) decays from new [aetriea]PbBr3perovskitoid showing 6 ns average lifetime. These results suggest that doubly charged cation hybrid perovskite materials are potential candidates for optoelectronic applications.

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35

Do, T. Anh Thu, Truong Giang Ho, Thu Hoai Bui, Quang Ngan Pham, Hong Thai Giang, Thi Thu Do, Duc Van Nguyen, and Dai Lam Tran. "Surface-plasmon-enhanced ultraviolet emission of Au-decorated ZnO structures for gas sensing and photocatalytic devices." Beilstein Journal of Nanotechnology 9 (March 1, 2018): 771–79. http://dx.doi.org/10.3762/bjnano.9.70.

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Pure and Au-decorated sub-micrometer ZnO spheres were successfully grown on glass substrates by simple chemical bath deposition and photoreduction methods. The analysis of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, energy-dispersive X-ray spectroscopy (EDS), UV–vis absorption, and photoluminescence (PL) spectra results were used to verify the incorporation of plasmonic Au nanoparticles (NPs) on the ZnO film. Time-resolved photoluminescence (TRPL) spectra indicated that a surface plasmonic effect exists with a fast rate of charge transfer from Au nanoparticles to the sub-micrometer ZnO sphere, which suggested the strong possibility of the use of the material for the design of efficient catalytic devices. The NO2 sensing ability of as-deposited ZnO films was investigated with different gas concentrations at an optimized sensing temperature of 120 °C. Surface decoration of plasmonic Au nanoparticles provided an enhanced sensitivity (141 times) with improved response (τRes = 9 s) and recovery time (τRec = 39 s). The enhanced gas sensing performance and photocatalytic degradation processes are suggested to be attributed to not only the surface plasmon resonance effect, but also due to a Schottky barrier between plasmonic Au and ZnO structures.

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36

Zhan, Jinglin, Zhizhong Chen, Chuhan Deng, Fei Jiao, Xin Xi, Yiyong Chen, Jingxin Nie, et al. "A Novel Way to Fill Green Gap of GaN-Based LEDs by Pinning Defects in Nanorod Array." Nanomaterials 12, no. 21 (November 3, 2022): 3880. http://dx.doi.org/10.3390/nano12213880.

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Nanorod array and planar green-emission InGaN/GaN multi-quantum well (MQW) LEDs were fabricated by lithography, nano-imprinting, and top–down etching technology. The defect-pinning effect of the nanostructure was found for the first time. The ratio of the bright regions to the global area in the panchromatic CL images of green MQW samples increased from 30% to about 90% after nano-fabrication. The overall luminous performance significantly improved. Throughout temperature-dependent photoluminescence (TDPL) and time-resolved PL (TRPL) measurements, the migration and recombination of carriers in the MQWs of green LEDs were analyzed. It was proved that nanostructures can effectively prevent carriers from being captured by surrounding nonradiative recombination centers. The overall PL integral intensity can be enhanced to above 18 times. A much lower carrier lifetime (decreasing from 91.4 to 40.2 ns) and a higher internal quantum efficiency (IQE) (increasing from 16.9% to 40.7%) were achieved. Some disputes on the defect influence were also discussed and clarified.

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37

Meli, Alessandro, Annamaria Muoio, Riccardo Reitano, Enrico Sangregorio, Lucia Calcagno, Antonio Trotta, Miriam Parisi, Laura Meda, and Francesco La Via. "Effect of the Oxidation Process on Carrier Lifetime and on SF Defects of 4H SiC Thick Epilayer for Detection Applications." Micromachines 13, no. 7 (June 30, 2022): 1042. http://dx.doi.org/10.3390/mi13071042.

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The aim of this work was a deep spectroscopical characterization of a thick 4H SiC epitaxial layer and a comparison of results between samples before and after a thermal oxidation process carried out at 1400 °C for 48 h. Through Raman and photoluminescence (PL) spectroscopies, the carrier lifetimes and the general status of the epilayer were evaluated. Time-resolved photoluminescence (TRPL) was used to estimate carrier lifetime over the entire 250 µm epilayer using different wavelengths to obtain information from different depths. Furthermore, an analysis of stacking fault defects was conducted through PL and Raman maps to evaluate how these defects could affect the carrier lifetime, in particular after the thermal oxidation process, in comparison with non-oxidated samples. This study shows that the oxidation process allows an improvement in the epitaxial layer performances in terms of carrier lifetime and diffusion length. These results were confirmed using deep level transient spectroscopy (DLTS) measurements evidencing a decrease in the Z1/2 centers, although the oxidation generated other types of defects, ON1 and ON2, which appeared to affect the carrier lifetime less than Z1/2 centers.

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38

Putro, Permono Adi, Liszulfah Roza, and Isnaeni Isnaeni. "Precursor Concentration Effect on Optical Properties of Carbon Dots from Cassava’s Peels." Journal of Physics: Theories and Applications 2, no. 2 (September 30, 2018): 43. http://dx.doi.org/10.20961/jphystheor-appl.v2i2.30664.

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Carbon dots (C-dots) are a new type of fluorescent nanoparticles that can be readily synthesized from natural sources, such as cassava’s peels. In this work, C-dots were synthesized from cassava’s peels using low temperature green synthesis based. The Green synthesis techniques were done by using water as a solvent non-chemical and natural sources. The Synthesis was done using various concentrations of precursor from 0.25%, 0.50%, 1.0% and 2.0%. Optical properties of C-dots were characterized using spectrophotometer UV-Vis, photoluminescence (PL) and time resolved photoluminescence (TRPL). The concentration of precursor lead to differences in molecular density and content of preparation thus affecting optical properties. The performance of C-dots optical properties were dominated by the transition of electrons n–π* on structure aromtic C=O which originate from the surface of C-dots. The result of C-dots sample with a concentration of 2.0% precursors has the best emission effiency. This provides the potential for C-dots cassava’s peels in the aqueous solution to be applied as cellular bioimaging and biosensing metal ions and salts.

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39

Deng, Jun, Zhibiao Hao, Lai Wang, Jiadong Yu, Jian Wang, Changzheng Sun, Yanjun Han, et al. "Studies on Carrier Recombination in GaN/AlN Quantum Dots in Nanowires with a Core–Shell Structure." Nanomaterials 10, no. 11 (November 20, 2020): 2299. http://dx.doi.org/10.3390/nano10112299.

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GaN quantum dots embedded in nanowires have attracted much attention due to their superior optical properties. However, due to the large surface-to-volume ratio of the nanowire, the impacts of surface states are the primary issue responsible for the degradation of internal quantum efficiency (IQE) in heterostructured dot-in-nanowires. In this paper, we investigate the carrier recombination mechanism of GaN/AlN dot-in-nanowires with an in situ grown AlN shell structure. Ultraviolet photoelectron spectroscopy (UPS) measurements were performed to describe the band bending effect on samples with different shell thicknesses. Temperature-dependent photoluminescence (TDPL) data support that increasing the AlN shell thickness is an efficient way to improve internal quantum efficiency. Detailed carrier dynamics was analyzed and combined with time-resolved photoluminescence (TRPL). The experimental data are consistent with our physical model that the AlN shell can effectively flatten the band bending near the surface and isolate the surface non-radiative recombination center. Our systematic research on GaN/AlN quantum dots in nanowires with a core–shell structure may significantly advance the development of a broad range of nanowire-based optoelectronic devices.

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40

Zhang, Qiqi, and Qilin Dai. "High-Performance Perovskite Solar Cells Fabricated By Solvent Volatilization Method." ECS Meeting Abstracts MA2022-02, no. 16 (October 9, 2022): 844. http://dx.doi.org/10.1149/ma2022-0216844mtgabs.

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Perovskite solar cells have attracted significant research efforts due to their remarkable performance, but most of them are prepared by the anti-solvent method. It’s not suitable for repeatability and large-scale production. We develop a perovskite film fabrication technique based on MAFAPbI3Cl precursor films, through annealing arrived recrystallization, forming high-quality perovskite films. The photovoltaic properties of the perovskite films fabricated with different experimental parameters are studied. The films prepared by our method show high reproducibility, facile operation, and significant potential in large-scale production. We use excess amount formanidinium iodide (FAI) to adjust the amount of methylammonium chloride (MACl) to optimize MAFAPbI3Cl precursor film. The experimental parameters include FAI amount and MACl amount are utilized to form high-quality perovskite films. Film structural and optical properties are studied by X-ray diffraction (XRD), UV-vis absorption spectra, photoluminescence (PL), time-resolved photoluminescence (TRPL) techniques. The best solar cell PCE reaches 20.64 % with the average PCE of 20%. These perovskite solar cells also exhibit excellent high stability and repeatability. We believe this work develops a way for the commercialization of perovskite solar cells.

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41

Santamaria, Luigi, Pasqualino Maddalena, and Stefano Lettieri. "An Instantaneous Recombination Rate Method for the Analysis of Interband Recombination Processes in ZnO Crystals." Materials 15, no. 4 (February 17, 2022): 1515. http://dx.doi.org/10.3390/ma15041515.

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Time-resolved photoluminescence (TRPL) analysis is often performed to assess the qualitative features of semiconductor crystals using predetermined functions (e.g., double- or multi-exponentials) to fit the decays of PL intensity. However, in many cases—including the notable case of interband PL in direct gap semiconductors—this approach just provides phenomenological parameters and not fundamental physical quantities. In the present work, we highlight that within a properly chosen range of laser excitation, the TRPL of zinc oxide (ZnO) bulk crystals can be described with excellent precision with second-order kinetics for the total recombination rate. We show that this allows us to define an original method for data analysis, based on evaluating the “instantaneous” recombination rate that drives the initial slope of the decay curves, acquired as a function of the excitation laser fluence. The method is used to fit experimental data, determining useful information on fundamental quantities that appear in the second-order recombination rate, namely the PL (unimolecular) lifetime, the bimolecular recombination coefficient, the non-radiative lifetime and the equilibrium free-carrier concentration. Results reasonably close to those typically obtained in direct gap semiconductors are extracted. The method may represent a useful tool for gaining insight into the recombination processes of a charge carrier in ZnO, and for obtaining quantitative information on ZnO excitonic dynamics.

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Wang, Wenjun, Molang Cai, Yunzhao Wu, Kangyu Ji, Bin Cheng, Xuepeng Liu, Hui Lv, and Songyuan Dai. "Defect Healing of MAPbI3 Perovskite Single Crystal Surface by Benzylamine." Symmetry 14, no. 6 (May 27, 2022): 1099. http://dx.doi.org/10.3390/sym14061099.

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Анотація:

Controlling the surface traps in metal halide perovskites (MHPs) is essential for device performance, stability, and commercialization. Here, a facile approach is introduced to passivate the methylammonium lead iodide (MAPbI3) perovskite single crystal (PSC) surface defects by benzylamine (BA) ligand treatment, and the natural crystallographic (100) facets surface of PSC is chosen as the research platform to provide a deeper understanding of the passivation process. The confocal photoluminescence (PL) results show that the pristine three-dimensional (3D) MAPbI3 PSC surface with a symmetric emission spectrum is normally converted to a pure two-dimensional (2D) BA2PbI4, and also forms a quasi-2D Ruddlesden–Popper perovskite (RPP) BA2MAn−1PbnI3n+1 (n = 2, 3, 4, … ∞) after BA exchange with cation defects. The blue shift in the PL peak, as well as the extended exciton lifetimes of time-resolved photoluminescence (TRPL), indicate the realization of surface defect passivation. Additionally, changes in surface morphology are also investigated. The reaction starts with the formation of small, layered crystallites over the surface; as time elapses, the layered crystallites spread and merge in contact with each other, eventually resulting in smooth features. Our findings present a simple approach for MAPbI3 PSC surface defect passivation, which aims to advance MHP optimization processes toward practical perovskite device applications.

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43

Yang, Jun, Quanxi Zhu, Taiping Xie, Jiankang Wang, Yuan Peng, Yajing Wang, Chenglun Liu, and Longjun Xu. "Insights into Interface Charge Extraction in a Noble-Metal-Free Doped Z-Scheme NiO@BiOCl Heterojunction." Catalysts 10, no. 9 (August 21, 2020): 958. http://dx.doi.org/10.3390/catal10090958.

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Анотація:

It is of great significance to thoroughly explore the interface charge extraction and migration in heterojunction systems, which could guide us to synthesize higher-efficiency photocatalytic materials. A novel noble-metal-free doped Z-scheme NiO@BiOCl heterojunction was found in this work. The corresponding heterostructure, interface electron extraction, and electron migration were investigated via first-principles calculation. 5,5′-dimethyl-1-pyrroline-N-oxide (DMPO) spin-trapping electron spin resonance (ESR) and time-resolved photoluminescence (TRPL) tests were implemented to confirm the calculation results, which showed that electrons and holes stayed in the NiO (100) facet and BiOCl (110) facet, respectively. Owing to the large chemical potential of 2.40 V (vs ENHE) for the BiOCl valence-band hole, it possessed super activity to oxidize water into hydroxyl radicals or molecular oxygen. We hope this promising multifunctional photocatalytic material, therefore, NiO@BiOCl can be applied in advanced treatment of organic wastewater and oxygen production from photolysis water.

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44

Zhang, Xue, Wenxian Yang, Zhiwei Xing, Haibing Qiu, Ying Gu, Lifeng Bian, Shulong Lu, et al. "Investigation of Micromorphology and Carrier Recombination Dynamics for InGaN/GaN Multi-Quantum Dots Grown by Molecular Beam Epitaxy." Crystals 11, no. 11 (October 27, 2021): 1312. http://dx.doi.org/10.3390/cryst11111312.

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Анотація:

InGaN quantum dots (QDs) are promising candidates for GaN-based all-visible optoelectronic devices such as micro light-emitting diode and laser. In this study, self-assembled InGaN/GaN multi-quantum dots (MQDs) have been grown by plasma-assisted molecular beam epitaxy on c-plane GaN-on-sapphire template. A high density of over 3.8 × 1010 cm−2 is achieved and InGaN QDs exhibit a relatively uniform size distribution and good dispersity. Strong localization effect in as-grown InGaN QDs has been evidenced by temperature-dependent photoluminescence (PL). The variation of peak energy is as small as 35 meV with increasing temperature from 10 K to 300 K, implying excellent temperature stability of emission wavelength for InGaN MQDs. Moreover, the radiative and nonradiative recombination times were calculated by time-resolved PL (TRPL) measurements, and the temperature dependence of PL decay times reveal that radiative recombination dominates the recombination process due to the low dislocation density of QDs structure.

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45

Kong, Ling Min, Cun Xi Zhang, Rui Wang, and Shi Lai Wang. "Structure and Photoluminescence Investigations of Self-Organized InAs/GaAs Quantum Wires." Advanced Materials Research 79-82 (August 2009): 1707–10. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1707.

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Self –organized InAs quantum wires (QWRs) were fabricated on the step edges of GaAs (331)A surface by molecular beam epitaxy (MBE). The atomic force microscopy (AFM) results show that the lateral size of InAs QWRs is 90 nm while the size along the step lines increasing with the thicknesses of InAs layers, amounting to 1100nm. The height of InAs QWRs varies from 7.9nm to 13nm. Photoluminescence (PL) measurements on the two samples were explored and an obvious PL peak around 967 nm was observed at 25 K. The PL intensity decreases as the temperature increases, and it will vanish above 60 K. However, the QWR sample with thicker InAs layer emits a long emission of 1100 nm -1400 nm as the temperature rises above 50 K, and a longer emission of 1400-1600nm as the temperature approaches to 100 K. We considered that the complex photoluminescence spectra were originated from the multiple energy steps. The carrier migration among the different QWRs structures intensified with temperature, and the chance rate from the higher energy levels to the lower ones which generated a stronger emission of long wavelength. The carrier dynamics of QWR samples were measured by using time resolved PL (TRPL) spectra from 25 K to 100 K. The PL decay time in the QWR structure at longer emission was found to be independent of the temperature as T<100 K, showing a typical dynamical behavior of the localized excitons.

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46

Strak, Pawel, Kamil Koronski, Konrad Sakowski, Kamil Sobczak, Jolanta Borysiuk, Krzysztof P. Korona, Piotr A. Dróżdż, et al. "Corrigendum to “Instantaneous decay rate analysis of time resolved photoluminescence (TRPL): Application to nitrides and nitride structures” [J. Alloy. Compd. 823 (2020) 153791]." Journal of Alloys and Compounds 921 (November 2022): 166093. http://dx.doi.org/10.1016/j.jallcom.2022.166093.

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47

Ghezellou, Misagh, Piyush Kumar, Marianne E. Bathen, Robert Karsthof, Einar Ö. Sveinbjörnsson, Ulrike Grossner, J. Peder Bergman, Lasse Vines, and Jawad Ul-Hassan. "The role of boron related defects in limiting charge carrier lifetime in 4H–SiC epitaxial layers." APL Materials 11, no. 3 (March 1, 2023): 031107. http://dx.doi.org/10.1063/5.0142415.

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Анотація:

One of the main challenges in realizing 4H–SiC (silicon carbide)-based bipolar devices is the improvement of minority carrier lifetime in as-grown epitaxial layers. Although Z1/2 has been identified as the dominant carrier lifetime limiting defect, we report on B-related centers being another dominant source of recombination and acting as lifetime limiting defects in 4H–SiC epitaxial layers. Combining time-resolved photoluminescence (TRPL) measurement in near band edge emission and 530 nm, deep level transient spectroscopy, and minority carrier transient spectroscopy (MCTS), it was found that B related deep levels in the lower half of the bandgap are responsible for killing the minority carriers in n-type, 4H–SiC epitaxial layers when the concentration of Z1/2 is already low. The impact of these centers on the charge carrier dynamics is investigated by correlating the MCTS results with temperature-dependent TRPL decay measurements. It is shown that the influence of shallow B acceptors on the minority carrier lifetime becomes neutralized at temperatures above [Formula: see text] K. Instead, the deep B related acceptor level, known as the D-center, remains active until temperatures above [Formula: see text] K. Moreover, a correlation between the deep level concentrations, minority carrier lifetimes, and growth parameters indicates that intentional nitrogen doping hinders the formation of deep B acceptor levels. Furthermore, tuning growth parameters, including growth temperature and C/Si ratio, is shown to be crucial for improving the minority carrier lifetime in as-grown 4H–SiC epitaxial layers.

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48

Pei, Zingway, Han-Yun Wei, and Yi-Chun Liu. "Exciton Up-Conversion by Well-Distributed Carbon Quantum Dots in Luminescent Materials for an Efficient Organic Light-Emitting Diode." Nanomaterials 12, no. 7 (April 1, 2022): 1174. http://dx.doi.org/10.3390/nano12071174.

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In this work, we proposed an efficient and straightforward up-conversion process to enhance the external quantum efficiency in a red-emission organic light-emitting diode (OLED). The carbon quantum dots in the luminescent materials initiated the up-conversion by doping the (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) in an amount of 0.001 wt. %, and the external quantum efficiency (EQE) increased from approximately 80% to 9.27% without spectrum change. The time-resolved photoluminescence was applied to understand the mechanism of EQE enhancement in the PCBM-doped OLED. Two decay-time constants fit the TRPL. After PCBM doping, the extended PL intensity indicated increased time constants. The time constants increased from 1.06 and 4.02 ns of the reference sample to 3.48 and 11.29 ns of the PCBM-doped material, respectively. The nonradiative energy transfer (NRET) mechanism was proposed responsible for the decay-time enhancement. The excitons in the PCBM, either by excitation or injection, will transfer to the phosphorescent material nonradiatively. As the PCBM has lower energy levels than the luminous material for electrons, the backward exciton transfer is a kind of up-conversion. With the increased amounts of excitons in the luminescent material, the luminescent external quantum efficiency and the decay-time increased. This up-conversion method is not limited to the red-emission OLED; it could also be applied to blue or green emission.

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49

Zhu, Hanxu, Yekun Ji, Lifang Chen, Weilin Bian, and Jinnan Wang. "Pt Nanowire-Anchored Dodecahedral Ag3PO4{110} Constructed for Significant Enhancement of Photocatalytic Activity and Anti-Photocorrosion Properties: Spatial Separation of Charge Carriers and PhotogeneratedElectron Utilization." Catalysts 10, no. 2 (February 8, 2020): 206. http://dx.doi.org/10.3390/catal10020206.

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Pt nanowire-anchored dodecahedral Ag3PO4{110} was constructed for organics photodegradation. SEM and TEM images confirmed that the Pt nanowires were grafted on dodecahedral Ag3PO4, which was entirely bounded by {110} facets. All the X-ray diffraction peaks of the samples were indexed to the body-centered cubic phase of Ag3PO4, indicating that Pt nanowire-anchored dodecahedral Ag3PO4 well maintained the original crystal structure. The rhombic dodecahedral Ag3PO4 entirely bounded by {110} facets achieved high photocatalytic activity. Due to the formation of a Schottky barrier, the Pt nanowires improved the separation of the charge carriers of Ag3PO4. Furthermore, they provided a fast expressway to transfer the photogenerated electrons and prolonged the lifetime of the charge carriers via long-distance transport, resulting in the accumulation of holes on Ag3PO4 for organics degradation. More importantly, the Pt nanowires improved the reduction potential of the photogenerated electrons for O2 reduction to ·O2−, which enhanced the photocatalytic activity and anti-photocorrosion properties of Ag3PO4. We found that 99.5% of Rhodamine B (RhB) could be removed over 0.5ωt% Pt nanowire-anchored dodecahedral Ag3PO4 within 10 min. Even after 10 cycles, the photocatalytic activity was still high. photoluminescence (PL), time-resolved photoluminescence (TRPL), UV–vis diffuse reflectance spectra (UV–visDRS), and photoelectrochemical analysis showed that Pt nanowire-anchored dodecahedral Ag3PO4 exhibited lower bandgap, higher photocurrent intensity, better electronic conductivity, and longer charge carriers lifetime than other types of Ag3PO4 crystals. Radical trapping experiments and electron paramagnetic resonance (EPR) analysis demonstrated that the holes were the main active species for organics photodegradation.

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50

Alhefeiti, Maryam, Falguni Chandra, Ravindra Kumar Gupta, and Na’il Saleh. "Dyeing Non-Recyclable Polyethylene Plastic with Photoacid Phycocyanobilin from Spirulina Algae: Ultrafast Photoluminescence Studies." Polymers 14, no. 22 (November 9, 2022): 4811. http://dx.doi.org/10.3390/polym14224811.

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Despite the enormous environmental damage caused by plastic waste, it makes up over one-third of globally produced plastics. Polyethylene (PE) wastes have low recycling but high production rates. Towards the construction of ionic solar cells from PE, the present work describes the loading of a bioactive photoacid phycocyanobilin (PCB) dye from the pigment of Spirulina blue–green algae (as a natural resource) on low-density polyethylene (LDPE) plastic film. Dyeing was confirmed by X-ray photoelectron spectroscopy (XPS). Upon excitation of the Soret-band (400 nm), the photoluminescence (PL) spectra of PCB in neat solvents revealed two prominent emission peaks at 450–550 and 600–700 nm. The first band assigned to bilirubin-like (PCBBR) species predominated the spectral profile in the highly rigid solvent glycerol and upon loading 0.45 % (w/w) of the dye on plastic. The photoluminescence excitation (PLE) spectra of PCB for the second region (Q-band) at 672 nm in the same solvents confirmed the ground state heterogenicity previously associated with the presence of PCBA (neutral), PCBB (cationic), and PCBC (anionic) conformers. Time-resolved photoluminescence (TRPL) measurements induced via excitation of all PCB species at 510 nm in methanol revealed three-lifetime components with τ1 = ~0.1 ns and τ2 = ~2 ns associated with PCBBR species and τ3 = ~5 ns pertinent to the long-living photoproduct X*. Decay-associated spectra (DAS) analysis of the photoluminescence transient spectra of the final dyed films in the solid-state confirmed the improved generation of the long-living photoproduct as manifested in a significant increase in the PL intensity (~100-fold) and lifetime value (~90 ns) in the Q-region upon loading 6.92 % (w/w) of the dye on plastic. The photoproduct species were presumably assigned to the deprotonated PCB species, suggesting improved ionic mobility. The potential implementation of the PCB-sensitized PE solid wastes for the fabrication of ionic solar cells is discussed.

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