Reaction Kinetics Regulation Suppressed Carrier Recombination Loss for High‐Efficient Solution‐Based Antimony Selenosulfide Photovoltaic Devices

Abstract Carrier recombination loss within the emerging antimony selenosulfide (Sb 2 (S,Se) 3 ) photovoltaic devices is a critical factor limiting the photovoltaic performance. Herein, a reaction kinetics regulation strategy is reported to simultaneously passivate deep‐level intrinsic defect and inhibit the oxide impurities in Sb 2 (S,Se) 3 absorber with the help of sodium borohydride (SB). The SB, on one hand due to the alkaline feature, can significantly promote the decomposition of selenourea and Sb 2 Se 3 formation, eliminating the deep‐level Sb S1 defects and reducing the V S defects, and on the other hand, owing to the reducing property, can restore SbO + ions to Sb 3+ , thus inhibiting the Sb 2 O 3 formation and improving heterogeneous nucleation with preferable [hk1] orientation. These collective influences have remarkably suppressed carrier recombination loss and strengthened carrier collection with optimal band alignment. Consequently, high‐efficient Sb 2 (S,Se) 3 photovoltaic devices with an efficiency of 10.62% (0.0684 cm 2 ) are gained, which is comparable to the latest‐recorded value of 10.7% (0.0389 cm 2 ). This work provides a feasible reaction kinetics regulation method for suppressing carrier recombination loss of Sb‐based chalcogenide materials and supplies precious instruction for preparing high‐performance optoelectronic devices.