Effect of metal oxide morphology on electron injection from CdSe quantum dots to ZnO

Performance of quantum dot sensitized solar cells relies on a rapid electron injection from quantum dot to metal oxide. We studied the injection process in CdSe-ZnO system by ultrafast time-resolved absorption spectroscopy for two types of acceptor morphologies-nanowires and nanoparticles films. Based on comparison between experimental data and Marcus theory, we demonstrate that the acceptor morphology has a significant impact on electron injection due to (i) change in material permittivity and (ii) different density of the band-edge states. The results open a reference to improve injection efficiency in quantum dot-metal oxide system by selection of the acceptor morphology.