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611.
We have analyzed the energetics of decay of the X
minus trion (exciton + electron) on the assumption that the exciton and trion are independent excitations of a single twodimensional semiconducting quantum well. For the first time, it has been shown that in filling a well with electrons from a selective donordoped matrix, the binding energy of the trion (of the electron with the exciton) increases linearly with a shift of the Fermi level into the depth of the c band. This agrees with the wellknown experimental data on the lowtemperature radiative decay (photoluminescence) of trions in the heterostructures ZnSe/Zn0.89Mg0.11S0.18Se0.82 and CdTe/Cd0.7Mg0.3Te. 相似文献
612.
V. A. Nikitenko K. É. Tarkpea I. V. Pykanov S. V. Mukhin S. G. Stoyukhin P. G. Pas'ko 《Journal of Applied Spectroscopy》2000,67(5):883-887
The principal results of the investigation of thermally stimulated electron–hole and ionic processes in hydrothermal and gas-phase ZnO single crystals preexcited at low temperatures, based on simultaneous study of photo-EPR and thermoluminescence (TL), are presented. The nature of the traps determining the TL peaks at 17, 24, 40, 53, 90–110, 140–150, and 160–200 K is discussed. In particular, it has been established that the lithium paramagnetic centers (LiZn
+–OI) play the role of hole traps in ZnO giving green and red TL in the temperature range 160–200 K and, in the case of association with small-sized donors, also TL in the temperature range 90–110 K. The other traps are electronic in character, and in the presence of acceptor lithium in the crystals, they form yellow-orange TL. Optical quenching of TL has been evaluated, and it has been found that there is a difference E 0.75 eV between the thermal and optical energies of ionization of lithium acceptors. Irreversible ionic processes associated with the healing of cationic vacancies at T 360–420 K have been revealed. 相似文献
613.
The purpose of this paper is to provide general information about basic physical processes involved in organic electroluminescence
and to present the main parameters and advantages of organic light emitting devices (OLEDs). 相似文献
614.
Hsiu-Fang Fan 《中国化学会会志》2023,70(6):1314-1325
Single-molecule techniques have been demonstrated as powerful tools to investigate individual protein-DNA interactions that are difficult to access by conventional biochemical techniques. These methods are popularly used to obtain valuable and detailed molecular mechanisms of enzyme functions. Currently, we have used single-molecule tethered particle motion to investigate protein-DNA interactions, including homologous recombination, site-specific recombination, DNA package, and the nucleosome remodeling process, and useful information was obtained. Here, we will describe the experimental designs and present the information obtained. 相似文献
615.
616.
617.
Correlation between Energy and Spatial Distribution of Intragap Trap States in the TiO2 Photoanode of Dye‐Sensitized Solar Cells 下载免费PDF全文
Dr. Yi Wang Dr. Dapeng Wu Dr. Li‐Min Fu Prof. Xi‐Cheng Ai Prof. Dongsheng Xu Prof. Jian‐Ping Zhang 《Chemphyschem》2015,16(10):2253-2259
The energy and spatial distribution of intragap trap states of the TiO2 photoanode of dye‐sensitized solar cells and their impact on charge recombination were investigated by means of time‐resolved charge extraction (TRCE) and transient photovoltage (TPV). The photoanodes were built from TiO2 nanospheroids with different aspect ratios, and the TRCE results allowed differentiation of two different types of trap states, that is, deep and shallow ones at the surface and in the bulk of the TiO2 particles, respectively. These trap states exhibit distinctly different characteristic energy with only a slight variation in the particle size, as derived from the results of the density of states. Analyses of the size‐dependent TPV kinetics revealed that in a moderate photovoltage regime of about 375–625 mV, the dynamics of electron recombination are dominated by shallow trap states in the bulk, which can be well accounted for by the mechanism of multiple‐trap‐limited charge transport. 相似文献
618.
Crafting Core/Graded Shell–Shell Quantum Dots with Suppressed Re‐absorption and Tunable Stokes Shift as High Optical Gain Materials 下载免费PDF全文
Dr. Jaehan Jung Chun Hao Lin Young Jun Yoon Sidney T. Malak Yaxin Zhai Prof. Edwin L. Thomas Prof. Valy Vardeny Prof. Vladimir V. Tsukruk Prof. Zhiqun Lin 《Angewandte Chemie (International ed. in English)》2016,55(16):5071-5075
The key to utilizing quantum dots (QDs) as lasing media is to effectively reduce non‐radiative processes, such as Auger recombination and surface trapping. A robust strategy to craft a set of CdSe/Cd1?xZnxSe1?ySy/ZnS core/graded shell–shell QDs with suppressed re‐absorption, reduced Auger recombination rate, and tunable Stokes shift is presented. In sharp contrast to conventional CdSe/ZnS QDs, which have a large energy level mismatch between CdSe and ZnS and thus show strong re‐absorption and a constrained Stokes shift, the as‐synthesized CdSe/Cd1?xZnxSe1?ySy/ZnS QDs exhibited the suppressed re‐absorption of CdSe core and tunable Stokes shift as a direct consequence of the delocalization of the electron wavefunction over the entire QD. Such Stokes shift‐engineered QDs with suppressed re‐absorption may represent an important class of building blocks for use in lasers, light emitting diodes, solar concentrators, and parity‐time symmetry materials and devices. 相似文献
619.
在双电子复合过程发生的能量范围内,发射X光子的原子过程除双电子复合过程外还有辐射复合、共振激发、共振复合以及直接激发原子过程.本文使用相对论组态相互作用方法计算了这些过程的截面,比较了在双电子复合过程发生的能量范围内这些原子过程的截面与双电子复合过程截面,探讨了这些过程对双电子复合过程的影响.研究结果表明,辐射复合截面随入射电子束能量的增大迅速减小,在双电子复合能量范围内几乎为一常数,可以作为本底来处理;共振激发和共振复合过程对双电子复合过程的影响可以忽略不计;当入射电子束能量高于靶离子的第一激发能时,电子碰撞直接激发截面与高Rydberg态的截面连成一片,随着入射电子束能量的增加,电子碰撞直接激发截面越来越大,这时必须考虑直接激发过程.使用相对论组态相互作用方法计算了类氖氙离子的双电子复合截面,其结果与已有的部分实验和理论结果很吻合. 相似文献
620.