8.2%-Efficiency hydrothermal Sb2S3 thin film solar cells by two-step RTP annealing strategy

Antimony sulfide (Sb2S3) solar cells fabricated via hydrothermal deposition have attracted widespread attention. The annealing crystallization process plays a crucial role in achieving optimal crystallinity in hydrothermal Sb2S3 thin films. Nevertheless, incomplete crystallization and the loss of sulfur at high-temperature contribute to defect recombination, constraining device performance. Herein, a two-step rapid thermal processing (RTP) annealing strategy is proposed to improve the crystal quality and efficiency of Sb2S3 solar cells. The annealing process in Ar protection with atmospheric pressure can suppress S loss caused by saturated vapor pressure. The two-step RTP annealing with the 330 degrees C low-temperature and 370 degrees C high-temperature process ensures high crystallinity and vertical orientations of Sb2S3 thin films, accompanied by a reduction in defect concentration from 1.01 x 10(12) to 5.97 x 10(11) cm(-3). The Sb2S3 solar cell achieves an efficiency of 8.20% with an enhanced open circuit voltage (V-OC) of 784 mV. The build-in voltage (V-bi) of 1.17 V and irradiation-dependent ideal factor (n) of 1.48 demonstrate enhanced heterojunction quality and suppressed defect recombination in the devices. The presented two-step annealing strategy and physical mechanism study will open new prospects for high-performance Sb2S3 solar cells.