Synthesis and Photochemistry of Quantum‐Size Semiconductor Particles in Solution and in Modified Layers

Abstract

Abstract We describe the preparation of highly monodisperse, quantum‐size CdS particles. In these samples a band splitting into discrete exciton‐like states is observed. A mechanism for the excitonic fluorescence is presented involving shallow traps as a reservoir for electrons which finally recombine with free positive holes across the bandgap. Quantum‐size CdS and PbS particles prepared in situ on highly porous, polycrystalline TiO 2 electrodes work as highly efficient sensitizers. Photocurrent yields of more than 70% are reported. In the case of PbS, it is shown that an efficient electron transfer is possible only with particles in the size of the quantization regime.