Hot-Electron Transfer from Semiconductor Nanocrystals

Abstract

Hot on the Trail Solar cells essentially operate by absorbing light, which needs to be above a certain energy threshold. The absorbed light then liberates charges within the solar cell to carry electrical current. Unfortunately, the liberated charges behave the same way whether they are excited right at the threshold (e.g., by visible light) or well above it (by ultraviolet light), which leads to any excess energy being dissipated as waste heat. Tisdale et al. (p. 1543 ) have documented a potential first step toward resolving this inefficiency. Specifically, electrons excited by light absorption in lead selenide nanocrystals were able to migrate to an adjacent titanium dioxide surface without releasing their excess energy to heat. The next step will be to devise a means of harnessing the stored energy in a circuit.