Double-shell SnO2/CeO2:Yb,Er hollow nanospheres as an assistant layer that suppresses charge recombination in dye-sensitized solar cells

Double-shell SnO2/CeO2:Yb,Er hollow nanospheres (HNSs) are prepared using SiO2 as a template. Firstly, CeO2:Yb,Er nanoparticles (NPs) were coated on the surface of SiO2 to generate core–shell SiO2@CeO2:Yb,Er nanospheres. Then the SiO2 cores were removed accompanied by SnO2 deposition to form heterogeneous double-shell SnO2/CeO2:Yb,Er HNSs during a hydrothermal process. It can be seen from the structure analysis that the deposition of the SnO2 shell as the framework supports the CeO2:Yb,Er shell. When SnO2/CeO2:Yb,Er HNSs act as an assistant layer in dye-sensitized solar cells (DSSCs), the photoelectric conversion efficiency (PCE) is enhanced to 8.66%. Open-circuit voltage decay confirms that the lifetime of photogenerated electrons in the cells is prolonged. Double-shell SnO2/CeO2:Yb,Er HNSs might efficiently suppress the recombination of photoproduced electrons–holes, extend the electron lifetime, and further improve the photoelectric conversion performance of DSSCs.