p‐Type Antimony Selenide via Lead Doping

p‐type doping in antimony selenide (Sb 2 Se 3 ) is an important issue to improve its photovoltaic performance, because the as‐grown Sb 2 Se 3 usually shows weak p‐type conductivity and leads to low open‐circuit voltage. However, no effective p‐type doping strategy has been reported so far. Herein, combining theoretical calculation and experiment, it is demonstrated that lead doping can effectively enhance the p‐type conductivity because of the low formation energy of the substitutional acceptor Pb Sb with a (–/0) transition level of 0.15 eV. This is further validated by a conductivity measurement that observes a shallow acceptor level. As a result, a free hole carrier density as high as 10 16 cm −3 is achieved for the first time. Furthermore, theoretical analysis on defect densities related to experimentally characterized device performances after Pb doping is presented. The study provides a new p‐type doping strategy as well as the implicit defect physics, which can be useful for further improvement of Sb 2 Se 3 solar cells.