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501.
For a highly beneficial mutant entering a randomly reproducing population of constant size, we study the situation when a second beneficial mutant arises before has fixed. If the selection coefficient of is greater than the selection coefficient of , and if and can recombine at some rate , there is a chance that the double beneficial mutant forms and eventually fixes. We give a convergence result for the fixation probability of and its fixation time for large selection coefficients. 相似文献
502.
Powerful recombination centers resulting from reactions of hydrogen with carbon–oxygen defects in n‐type Czochralski‐grown silicon
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503.
Electroluminescence of LED heterostructures with active layer made of InAsSb films grown on InAs substrates was studied in the temperature range T = 4.2–300 K. At low temperatures (T = 4.2–100 K), stimulated emission was observed with an optical cavity formed normal to the growth plane. The emission became spontaneous at higher temperatures due to the resonant “switch-on” of the CHHS Auger recombination process in which the energy of a recombining electron-hole pair is transferred to a hole transitioning to the spin-orbit-splitted band. The spontaneous character of emission continued up to room temperature because of the influence of other Auger processes. The results obtained suggest that InAsSb-based LED heterostructures are promising for the fabrication of vertically-emitting mid-infrared lasers. 相似文献
504.
505.
《Current Applied Physics》2014,14(3):340-344
We present an analytical model for bulk heterojunction organic solar cells incorporating the physics of recombination in the transport equations. Monomolecular recombination process is considered to be the dominant mechanism and treated explicitly. The proposed analytical model shows good agreement with the experimental data as well as with the numerical simulations. The improvements over the previous models are also presented to show the importance of considering the recombination process. The model can be used to find device characteristics such as current–voltage characteristic, efficiency etc. of bulk heterojunction organic solar cells avoiding the mathematical complexities of numerical models. 相似文献
506.
Three-dimensional simulation methodology has been used to evaluate the performance of lattice matched InGaAs/InP double layer planar heterointerface detector arrays. The device characteristics under optical illumination and dark conditions have been computed. The modulation transfer function (MTF) profiles have been calculated with varying device geometries and carrier dynamics. It is found that the p well diffusion radius and minority carrier recombination play important roles in the MTF behaviors of dense arrays. Moderate p well diffusion dimension should be used to balance the device performances between the dark current and MTF profile. Moreover, better MTF characteristic under low light condition can be achieved with higher quality material which has longer recombination lifetime. The influences of underlying mechanisms including photon generated carriers diffusion and carrier recombination processes have been discussed. These simulation methods and results should provide a useful tool for the evaluation and improvement of imaging power of InGaAs focal plane arrays. 相似文献
507.
Charge Localization Induced by Reorientation of FA Cations Greatly Suppresses Nonradiative Electron-Hole Recombination in FAPbl3 Perovskites: a Time-Domain Ab Initio Study
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Recent experiments report the rotation of FA (FA = HC[NH2]2\begin{document}$ ^+ $\end{document} ) cations significantly influence the excited-state lifetime of FAPbI3. However, the underlying mechanism remains unclear. Using ab initio nonadiabatic (NA) molecular dynamics combined with time-domain density functional simulations, we have demonstrated that reorientation of partial FA cations significantly inhibits nonradiative electron-hole recombination with respect to the pristine FAPbI3 due to the decreased NA coupling by localizing electron and hole in different positions and the suppressed atomic motions. Slow nuclear motions simultaneously increase the decoherence time, which is overcome by the reduced NA coupling, extending electron-hole recombination time scales to several nanoseconds and being about 3.9 times longer than that in pristine FAPbI3, which occurs within sub-nanosecond and agrees with experiment. Our study established the mechanism for the experimentally reported prolonged excited-state lifetime, providing a rational strategy for design of high performance of perovskite solar cells and optoelectronic devices. 相似文献
508.
Rui-Rong Bai Cai-Rong Zhang You-Zhi Wu Li-Hua Yuan Mei-Ling Zhang Yu-Hong Chen Zi-Jiang Liu Hong-Shan Chen 《International journal of quantum chemistry》2020,120(4):e26103
The morphology of donor-acceptor heterojunction interface significantly affects the electron/hole processes in organic solar cells, including charge transfer (CT), exciton dissociation (ED), and charge recombination (CR). Here, to investigate interface molecular configuration effects, the donor-acceptor complexes with face-on, edge-on, and end-on configurations were constructed as model systems for the p-SIDT(FBTTh2)2/C60 heterojunction. The geometries, electronic structures, and excitation properties of monomers and the complexes with three configurations were studied based on density functional theory (DFT) and time-dependent DFT calculations with optimally tuned range separation parameters and solid polarization effects. In terms of Marcus theory, the rate constants of ED and CR processes were analyzed. The results show that most of the excited states for p-SIDT(FBTTh2)2 exhibit an intramolecular CT character, and the similarity of the excitation characters (CT and local excitation) and energies among three complexes with different configurations indicate that the electronic structure and excitation properties are insensitive to the interfacial molecular configurations. However, the rates of ED and CR processes heavily depend on it. These results underline the importance of controlling molecular configuration and then the morphology at the heterojunction interface in organic solar cells. 相似文献
509.
510.
F.E. Fujita 《辐射效应与固体损伤》2013,168(1-2):165-170
Various possible and conceivable mechanisms of vacancy production in crystal during rapid deformation are considered, in attempt to explain how a large number of vacancy clusters can be produced with or without existence of dislocations during ultra-high-speed deformation of crystalline materials and to determine whether or not vacancy formation alone can effect deformation. Theoretical discussions mainly address the geometrical aspect of vacancy production, and are, therefore, neither quantitative in nature nor conclusive. Nevertheless, in connection with the present note, the author wishes to emphasize the importance of vacancy production in ultra-high-speed deformation of materials. 相似文献