Abstract
We provided a new method to improve the efficiency of Sb&sub2;S&sub3; thin film solar cells. The TiO&sub2; electron transport layers were doped by lithium to improve their charge extraction properties for the thermal-evaporated Sb&sub2;S&sub3; solar cells. The Mott-Schottky curves suggested a change of energy band and faster charge transport in the Li-doped TiO&sub2; films. Compared with the undoped TiO&sub2;, Li-doped mesoporous TiO&sub2; dramatically improved the photo-voltaic performance of the thermal-evaporated Sb&sub2;S&sub3; thin film solar cells, with the average power conversion efficiency (PCE) increasing from 1.79% to 4.03%, as well as the improved open-voltage (Voc), short-circuit current (Jsc) and fill factors. The best device based on Li-doped TiO&sub2; achieved a power conversion efficiency up to 4.42% as well as a Voc of 0.645 V, which are the highest values among the reported thermal-evaporated Sb&sub2;S&sub3; solar cells. This study showed that Li-doping on TiO&sub2; can effectively enhance the charge extraction properties of electron transport layers, offering a new strategy to improve the efficiency of Sb&sub2;S&sub3;-based solar cells.