摘要： In this work, two-dimension (2D) α-In2Se3 nanosheet, a binary III-VI group compound semiconductor, is fabricated by liquid phase exfoliation method, and the photoelectric properties of α-In2Se3 material are investigated in depth. It is found that α-In2Se3 film exhibits significant conductivity, outstanding optical transmission and suitable work function. Combined with its smooth surface and preferable hydrophobicity, α-In2Se3 film can efficiently facilitate hole transporting in the polymer solar cells (PSCs). Owing to the aforesaid advantages, 2D α-In2Se3 nanosheet is employed as a hole transport layer (HTL) in conventional PSCs for the first time, and a relatively high power conversion efficiency (PCE) of 9.58% is achieved with the structure of ITO/α-In2Se3/PBDB-T:ITIC/Ca/Al, which is comparable to PEDOT:PSS-based devices (9.50%). Interestingly, it is demonstrated that α-In2Se3 film possesses excellent thermal stability in the range from room temperature to 280 °C and a PCE of 9.35% is achieved without annealing treatment of α-In2Se3 film, which exhibits a great potential of α-In2Se3 for annealing-free approach. Furthermore, the incorporation of α-In2Se3 HTL also remarkably enhances the long-term stability of PSCs compared with PEDOT:PSS-based devices. So the results show that 2D α-In2Se3 is a promising candidate to be an efficient and stable hole extraction layer.