Solution-processed Ga-TiO2 electron transport layer for efficient inverted organic solar cells

•Ga-doped TiO2 film is synthesized using solution-processing techniques.•High photovoltaic parameters are achieved when used in inverted organic solar cells.•Superior efficiency at 7.72% is attained in the Ga-doped TiO2 based solar cell.•High efficiency is attributed to the improved charge transport and energy level.