ENGINEERING THE INTERFACE ENERGETICS OF SOLAR-CELLS BY GRAFTING MOLECULAR-PROPERTIES ONTO SEMICONDUCTORS

The electronic properties of semiconductor surfaces can be controlled by binding tailor-made ligands to them. Here we demonstrate that depos ition of a conducting phase on the treated surface enables control of the performance of the resulting device. We describe the characteristi cs of the free surface of single crystals and of polycrystalline thin films of semiconductors that serve as absorbers in thin film polycryst alline, heterojunction solar cells, and report first data for actual c ell structures obtained by chemical bath deposition of CdS as the wind ow semiconductor. The trend of the characteristics observed by systema tically varying the ligands suggests changes in work function rather t han in band bending at the free surface, and implies that changes in b and line-up, which appear to cause changes in band bending, rather tha n direct, ligand-induced band bending changes, dominate.