Charge carrier dynamics in CdSe nanocrystals: implications for the use of quantum dots in novel photovoltaics
Department of Chemistry, Vanderbilt University,
Box 1822 Station B, Nashville, TN 37235, USA
Published online: 15 September 2001
The dynamics of photo-generated electrons and holes in CdSe quantum dots have been studied using the femtosecond fluorescence upconversion technique, permitting an unambiguous examination of the excited state. The band edge emission shows an expected size dependence on the decay rate. We find that the deep trap emission is coupled to the band edge fluorescence, implicating surface states as important factors in the excited state lifetime of the hole. As a factor of the overall efficiency of solar cells, the rate of charge separation and the fate of the exciton are important considerations in the design of nanocrystal-based photovoltaic devices.
PACS: 81.07.Ta – Quantum dots / 82.53.Mj – Femtosecond probing of semiconductor nanostructures / 84.60.Jt – Photoelectric conversion: solar cells and arrays
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001