Direct Hydrothermal Deposition of Antimony Triselenide Films for Efficient Planar Heterojunction Solar Cells.

Antimony selenide (SbSe) has attracted increasing attention in photovoltaic applications due to its unique quasi-one-dimensional crystal structure, suitable optical band gap with a high extinction coefficient, and excellent stability. As a promising light-harvesting material, the available synthetic methods for the fabrication of a high-quality film have been quite limited and seriously impeded both the fundamental study and the efficiency improvement. Here, we developed a facile and low-cost hydrothermal method for in situ deposition of SbSe films for solar cell applications. In this process, we apply KSbCHO and NaSeSO as the antimony and selenium sources, respectively, in which thiourea (TU) serves as an additive to suppress the formation of SbO impurities. As a result, improved phase purity and enhanced crystallinity of the SbSe film are thus obtained, along with decreased trap states. Finally, the planar heterojunction SbSe solar cell delivered a power conversion efficiency of 7.9%, which is thus far the highest reported efficiency among solution-processed SbSe solar cells. This simple procedure and efficiency achievement demonstrate the great potential of the hydrothermal deposition process for the fabrication of high-efficiency SbSe solar cells.