Enhancement of the band edge emission of CdSe nano-tetrapods by suppression of surface trapping

Abstract

Preparation of CdSe nano-tetrapods in a controlled environment, using a glove box for the preparation of the Se precursor, was found to eliminate radiative surface trap emission to a large extent. This manifested in an increase in the band edge photoluminescence quantum yield by a factor of 20 and a concomitant decrease in the surface trap emission by a factor of 8. Interestingly, the time for recovery of ground state bleaching was more or less the same in the two kinds of nano-tetrapods, even though the photoluminescence dynamics are significantly slower in the more emissive ones. In single emissive nano-tetrapods, the kinetic traces for ground state bleaching recovery became gradually faster upon increasing the pump power. This is likely to be due to the effect of multiexciton relaxation and nonradiative Auger recombination.