Amphiphilic Graft Copolymers as Templates for the Generation of Binary Metal Oxide Mesoporous Interfacial Layers for Solid-State Photovoltaic Cells.

The binary metal oxide mesoporous interfacial layers (bi-MO meso IF layer) templated by a graft copolymer are synthesized between a fluorine-doped tin oxide (FTO) substrate and nanocrystalline TiO 2 (nc-TiO 2 ). Amphiphilic graft copolymers, Poly(epichlorohydrin)- graft -poly(styrene), PECH- g -PS, were used as a structure-directing agent, and the fabricated bi-MO meso IF layer exhibits good interconnectivity and high porosity. Even if the amount of ZnO in bi-MO meso IF layer increased, it was confirmed that the morphology and porosity of the bi-MO meso IF layer were well-maintained. In addtion, the bi-MO meso IF layer coated onto FTO substrates shows higher transmittance compared with a pristine FTO substrate and dense-TiO 2 /FTO, due to the reduced surface roughness of FTO. The overall conversion efficiency ( η ) of solid-state photovoltaic cells, dye-sensitized solar cells (DSSCs) fabricated with nc-TiO 2 layer/bi-MO meso IF layer TZ1 used as a photoanode, reaches 5.0% at 100 mW cm -2 , which is higher than that of DSSCs with an nc-TiO 2 layer/dense-TiO 2 layer (4.2%), resulting from enhanced light harvesting, good interconnectivity, and reduced interfacial resistance. The cell efficiency of the device did not change after 15 days, indicating that the bi-MO meso IF layer with solid-state electrolyte has improved electrode/electrolyte interface and electrochemical stability. Additionally, commercial scattering layer/nc-TiO 2 layer/bi-MO meso IF layer TZ1 photoanode-fabricated solid-state photovoltaic cells (DSSCs) achieved an overall conversion efficiency ( η ) of 6.4% at 100 mW cm -2 .