The efficiency of CdS quantum dot-sensitized Zn2SnO4 solar cells (QDSSCs) was improved by a novel surface treatment with Al3+ ions. The driving force for electron injection was strengthened for QDSSCs owing to the reduced conduction band edge of Zn2SnO4. The efficiency of Al3+ ions-treated solar cells were improved by 44% compared with the untreated ones. Polarization measurements proved the positive movement of the Zn2SnO4 conduction band edge. Although the deposited amounts of CdS QDs decreased after the surface treatment, the electron lifetimes were prolonged and the interfacial charge recombination was inhibited, giving rise to a greatly improved short-circuit current and efficiency. By optimizing the number of cycles of chemical bath deposition, a maximum efficiency of 0.263% was achieved under the illumination of one sun (AM1.5, 100 mW cm(-2)). (C) 2011 Elsevier Ltd. All rights reserved.