Recent progress in material study and photovoltaic device of Sb2Se3

Abstract

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 (Voc = 0.52 V, Jsc = 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% (Voc=0.335 V, Jsc=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.