Universal Elaboration of Al-Doped TiO2 as an Electron Extraction Layer in Inorganic-Organic Hybrid Perovskite and Organic Solar Cells

Fabricating an electron extraction layer (EEL) with a metal doping transition metal oxide (TMO) in inorganic-organic hybrid perovskite solar cells (PeSCs) and organic solar cells (OSCs) is a simple and efficient process for enhancing photovoltaic properties. Here, the universal benefits and common factors that influence both PeSCs and OSCs as a result of changes in Al-doped TiO2 properties are investigated. These common factors are identified in two separate mechanisms. The first involves surface smoothing of TiO2 films, which affects the formation of a high crystalline active layer and reduces recombination between the electron extraction and active layers. The second involves bandgap widening of TiO2, which reduces the activation energy and enhances the quenching efficiency of devices. These factors are demonstrated in various measurements. The results will help in understanding the fundamental benefits of Al-doped TiO2 in solution-processed thin-film solar cells.