Photoelectrochemical solar cells (PECs) consisting of a photoanode were prepared by direct deposition of independently synthesized CdSe nanocrystal quantum dots (NQDs) onto a nanocrystalline TiO.sub.2 film (NQD/TiO.sub.2), aqueous Na.sub.2S or Li.sub.2S electrolyte and a Pt counter electrode. The light harvesting efficiency (LHE) of the NQD/TiO.sub.2 photoanode is significantly enhanced when the NQD surface passivation is changed from tri-n-octylphosphine oxide (TOPO) to a smaller ligand (e.g. n-butylamine (BA)). Using NQDs with a shorter passivating ligand, BA, leads to a significant enhancement in both the electron injection efficiency at the NQD/TiO.sub.2 interface and charge collection efficiency at the NQD/electrolyte interface, with the latter attributed mostly to a more efficient diffusion of the electrolyte through the pores of the photoanode. By utilizing BA capped NQDs and aqueous Li.sub.2S as an electrolyte, it is possible to achieve about 100% internal quantum efficiency of photon-to-electron conversion, matching the performance of dye sensitized solar cells.
STATEMENT REGARDING FEDERAL RIGHTS
 This invention was made with government support under Contract No. DE-AC52-06NA25396 awarded by the U.S. Department of Energy and made under CRADA number LA08C10583 with the SHARP Corporation. The government has certain rights in the invention.