Size-Dependent Trap-Assisted Auger Recombination in Semiconductor Nanocrystals
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- 作者：Alicia W. Cohn ; Alina M. Schimpf ; Carolyn E. Gunthardt ; Daniel R. Gamelin
- 刊名：Nano Letters
- 出版年：2013
- 出版时间：April 10, 2013
- 年：2013
- 卷：13
- 期：4
- 页码：1810-1815
- 全文大小：285K
- 年卷期：v.13,no.4(April 10, 2013)
- ISSN：1530-6992
文摘
The acceleration of Auger-type multicarrier recombination in semiconductor nanocrystals impedes the development of many quantum-dot photonics, solar-cell, lighting, and lasing technologies. To date, only multiexciton and charged-exciton Auger recombination channels are known to show strong size dependence in nanocrystals. Here, we report the first observation of strongly accelerated 鈥渢rap-assisted鈥?Auger recombination rates in semiconductor nanocrystals. Trap-assisted Auger recombination in ZnO nanocrystals, involving the recombination of conduction-band electrons with deeply trapped holes via nonradiative energy transfer to extra conduction-band electrons, has been probed using time-resolved photoluminescence and transient absorption spectroscopies. We demonstrate that this trap-assisted Auger recombination accelerates dramatically with decreasing nanocrystal size, having recombination times of >1 ns in the largest nanocrystals but only 80 ps in the smallest. These trap-assisted Auger recombination rates are shown to scale with inverse nanocrystal radius squared (1/蟿Auger R鈥?). Because surface carrier traps are ubiquitous in colloidal semiconductor nanocrystals, such fast trap-assisted Auger recombination is likely more prevalent in semiconductor nanocrystal photophysics than previously recognized.