The　dye-sensitized　Zn2SnO4　solar　cells　were　treated　with　Al3+　ions　to　enhance　the　power　conversion　efficiency　for　the　first　time.　Usually,　the　surface　treatment　on　photoanodes　with　Al3+　ions　generated　an　overlayer　of　Al2O3.　For　Zn2SnO4　photoanode,　another　reaction　pathway　was　found.　The　treatment　with　Al3+　ions　led　to　decreasing　open　circuit　voltage,　and　a　22.6%　enhancement　of　efficiency.　Mott-Schottky　measurements　revealed　that　the　flat　band　of　Zn2SnO4　had　a　positive　shift　owing　to　the　introduction　of　Al3+　ions.　XPS　confirmed　that　Al3+　ions　were　introduced　into　the　lattice　of　Zn2SnO4　and　occupied　the　position　of　Se,　resulting　in　decreased　conduction　band　edge.　TEM　demonstrated　the　size　of　Zn2SnO4　nanoparticles　became　larger　due　to　the　reaction　of　Al3+　with　Zn2SnO4.　Although　the　adsorption　amounts　of　dyes　lowered　by　21%,　the　driving　force　for　electron　injection　was　greatly　enhanced　as　a　result　of　decreased　conduction　band　edge,　resulting　in　significantly　enhanced　cell　efficiency.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.