George Mason University , Fairfax, Virginia 22030, United States.
Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia.
Nano Lett. 2016 Apr 13;16(4):2503-11. doi: 10.1021/acs.nanolett.6b00066. Epub 2016 Mar 15.
A theoretical study of the positive and negative trion channels in the nonradiative Auger recombination of band-edge biexcitons (BXs) in CdSe/CdS core/shell nanocrystals (NCs) is presented. The theory takes into account the BX fine-structure produced by NC asymmetry and hole-hole exchange interaction. The calculations show that growth of CdS shell upon CdSe core suppresses the rate of the Auger recombination via negative trion channel, while the more efficient Auger recombination via positive trion channel shows much weaker dependence on the shell thickness. The demonstrated oscillatory dependence of the BX Auger rate on the core and shell sizes is explained qualitatively in terms of overlap of the ground and excited carrier wave functions. The calculations show that raise of temperature accelerates the Auger recombination in CdSe/CdS NCs due to reduction of the bulk energy gaps of CdSe and CdS.
本文对 CdSe/CdS 核壳纳米晶体（NCs）中带边双激子（BX）非辐射俄歇复合过程中正、负三体通道进行了理论研究。该理论考虑了 NC 非对称和空穴-空穴交换相互作用引起的 BX 精细结构。计算表明，CdS 壳层在 CdSe 核上的生长通过负三体通道抑制了俄歇复合速率，而通过正三体通道的更有效的俄歇复合对壳层厚度的依赖性则小得多。根据激发和基态载流子波函数的重叠，定性地解释了 BX 俄歇复合速率对核和壳尺寸的振荡依赖性。计算表明，由于 CdSe 和 CdS 的体能隙减小，升高温度会加速 CdSe/CdS NCs 中的俄歇复合。
