Novel Insight into the Role of Chlorobenzene Antisolvent Engineering for Highly Efficient Perovskite Solar Cells: Gradient Diluted Chlorine Doping.

Chlorobenzene and diethyl ether were chosen as an antisolvent to control the crystallization of CHNHPbI. Under the condition of similar crystallization for both perovskite films, the obvious larger short-circuit current density for CHNHPbI film treated by chlorobenzene prompted us to unveil the roles of chlorobenzene in the perovskite films via adjusting the dropping amount of chlorobenzene. A novel insight of chlorobenzene function was revealed, that is, gradient diluted chlorine doping in the CHNHPbI film, which forms a gradient band gap in the perovskite films, prompts photogenerated carriers accumulating at the interface, makes the electron transport faster, and effectively enhances the power conversion efficiency (PCE) of solar cells. The maximum PCE of 20.58% has been achieved under standard AM1.5 conditions. Moreover, this technique exhibits very high reproducibility, and 20 devices fabricated in one batch can yield an average PCE of 20.31%.