Matthew Pelton, Jordan J. Andrews, Igor Fedin, Dmitri V. Talapin, Haixu Leng, and Stephen K. O’Leary
Nano Letters, Vol. 17, Page 6900 (2017)
Abstract: Non-radiative Auger recombination limits the efficiency with which colloidal semiconductor nanocrystals can emit light when they are subjected to strong excitation, with important implications for application of the nanocrystals in light-emitting diodes and lasers. This has motivated attempts to engineer the structure of the nanocrystals in order to minimize Auger rates. Here, we study Auger recombination rates in CdSe/CdS core/shell nanoplatelets, or colloidal quantum wells. Using time-resolved photoluminescence measurements, we show that the rate of biexcitonic Auger recombination has a non-monotonic dependence on the shell thickness, initially decreasing, reaching a minimum for shells with thickness of 2 – 4 monolayers, and then increasing with further increases in the shell thickness. This non-monotonic behavior has not previously been observed for biexcitonic recombination in quantum dots, most likely due to inhomogeneous broadening that is not present for the nanoplatelets.