Nanosized　Y2O3:　RE3+　(RE=Eu　and　Er)　particles　with　the　cubic　crystal　structure　and　a　novel　morphology　were　prepared　via　a　low　temperature　process　to　be　applied　as　near　ultraviolet　and　near　infrared　light-harvesting　materials　in　dye-sensitized　solar　cells　(DSSCs).　These　phosphor　particles　consisted　of　triangular　prisms　that　were　built　from　nanosheets　by　a　self-assembly　process,　leading　to　neatly-aligned　structures.　The　photoluminescence　of　the　phosphor　films　was　characteristic　for　Eu3+　and　Er3+　dopants　in　cubic　Y2O3　and　matched　the　spectral　absorption　of　the　selected　sensitizers　of　the　DSSCs　used　in　this　study　quite　well.　It　was　found　that　Y2O3:　Er　luminescence　films　in　DSSCs　increased　the　energy　conversion　efficiency　by　13.6%　in　comparison　to　reference　DSSCs　coated　with　a　non-doped　Y-2　O-3　film.　On　the　other　hand,　DSSCs　with　Y2O3:　Eu　luminescence　films　did　not　show　increased　photovolaic　efficiency.