Efficient monolithic dye sensitized solar cells with eco-friendly silica-titania spacer layers

•SiO2-TiO2 electrical spacer layers for efficient monolithic DSSCs were developed.•Pastes for electrical spacers layer derived from entirely water-based formulations.•Boost of spacer layer reflectance occurs at threshold TiO2 content of 30 wt%.•Monolithic DSSCs with power conversion efficiency of 8.3% were produced.