新型硒化锑材料及其光伏器件研究进展

硒化锑(Sb₂Se₃)是一种二元单相化合物, 原料储量大、毒性低、价格便宜; 同时其禁带宽度合适(～1.15 eV), 吸光系数大(>10⁵ cm^-1), 长晶温度低, 非常适合制作新型低成本低毒的薄膜太阳能电池, 理论光电转换效率可达30%以上. 目前文献报道的Sb₂Se₃薄膜太阳能电池效率已达3.7%, 初步证明了Sb₂Se₃材料在薄膜太阳能电池应用方面的巨大潜力. 本文综述了近年来Sb₂Se₃太阳能电池的研究进展, 着重介绍了Sb₂Se₃的材料特性和薄膜制备及相关理论研究, 阐述了不同结构电池器件的研究进展, 并对其发展趋势进行了展望.

Recent progress in material study and photovoltaic device of Sb2Se3

Recently, antimony selenide (Sb₂Se₃) has been proposed as an alternative earth-abundant absorber material for thin film solar cells. Sb₂Se₃ is a simple V₂-VI₃ binary compound with an orthorhombic crystal structure and a space group of Pnma 62. It is a staggered layered compound consisting of parallel 1D (Sb₄Se₆)_n ribbons held together by weak van der Waals forces. Sb₂Se₃ has a direct band gap of approximately 1.15 eV with a large absorption coefficient (>10⁵ cm^-1, at short wavelength) and a low grain growth temperature (～300^{o}C), facilitating the fabrication of low-cost thin film solar cells. Moreover, it is a simple binary compound in single phase with a fixed composition, which provides a much simpler growth chemistry than the multicomponent Cu₂ZnSn(S,Se)₄. In addition, it is stable upon exposure to the ambient air, thus having a better prospect for long-term stability than the organic-inorganic halide perovskite solar cells. Theoretical analysis indicates that the efficiency limit is >30% for single junction Sb₂Se₃ solar cells. Various approaches, including vacuum evaporation, electrodeposition, spray pyrolysis, and chemical bath deposition (CBD), have been explored to produce Sb₂Se₃ thin films; however, it is only in these years that Sb₂Se₃ solar cells have been reported by our group as well as by others. Seok's group presented the deposition of Sb₂Se₃ on mesoporous TiO₂ films by thermal decomposition of Sb₂Se₃ single-source precursors, and fabricated Sb₂Se₃-sensitized inorganic-organic heterojunction solar cells with a remarkable efficiency of 3.21%. Tena-Zaera's group fabricated the FTO/TiO₂/Sb₂Se₃/CuSCN/Au heterojunction device and achieved 2.1% device efficiency; their Sb₂Se₃ was obtained by an electrodeposition route and CuSCN served as a hole conducting layer. Different from the above Sb₂Se₃-sensitized solar cells reported by other groups, our group is the first in the world working on Sb₂Se₃ thin film solar cells so far as wu know. We have fabricated a hydrazine solution-processed TiO₂/Sb₂Se₃ heterojunction solar cell, achieving 2.26% device efficiency (V_oc = 0.52 V, J_sc = 10.3 mA/cm² and m FF = 42.3%). In addition to the solution processing method, thermal-evaporated substrate and superstrate CdS/Sb₂Se₃ thin film solar cells with 2.1% and 1.9% efficiencies respectively were also demonstrated by our group. Recently, we have further improved the superstrate device performance to 3.7% (V_oc=0.335 V, J_sc=24.4 mA/cm², and m FF=46.8%$) by using a post selenization step. Selenization can compensate the Se loss during thermal evaporation, attenuate selenium vacancy-related recombination loss and hence improve the device performance. In summary, this paper summarizes the recent research progress in Sb₂Se₃-related researches, including material properties of Sb₂Se₃, synthesis of Sb₂Se₃ nanomaterials and thin films, theoretical studies on electrical properties, device configuration and efficiency improvement of Sb₂Se₃ sensitized and thin film solar cells. This review also presents a perspective on future development of Sb₂Se₃ solar cells.