Advances in the fabrication and understanding of colloidally grown nanocrystal quantum dots, nanorods and nanowires have been driven by intense interest in their potential applications. These applications include biological labels, as well as tunable optoelectronic devices such as light emitting diodes, lasers, detectors and photovoltaics.
In this talk we show that by controlling the size and shape of our nanostructures, it is possible to tailor optoelectronic properties such as, bandgap, electron and hole mobility as well as the exciton (i.e. electron-hole pair) dynamics. In particular, we report a significant enhancement of multiple exciton generation in PbSe nanorods over nanocrystal quantum dots characterized by a 2-fold increase in efficiency and reduction of the threshold energy to 2.2Eg, which approaches the theoretical limit of 2Eg. The creation of a single exciton per incident photon is a fundamental limitation for current optoelectronic devices including photodetectors and photovoltaic cells. The prospect of multiple exciton generation per incident photon is of great interest to fundamental science and the improvement of solar cell technology. Realization of high efficient nanostructure based photovoltaics require further improvements in the electron and hole transport as well as nanostructure passivation. Current accomplishments in these matters will be discussed.