The role of different window layers in Sb2Se3-based thin film solar cells.

In recent years antimony selenide (Sb2Se3) is being studied as an innovative p-type absorber material for polycrystalline thin film solar cells. The reason for the interest in this material stems from the low cost and from the abundance of the component elements on the earth crust, as well as for its suitable physical properties. In fact, it exhibits an attractive energy gap that falls in the range of the maximum of the Schottky-Queisser curve, it presents also a high absorption coefficient (α>105 cm-1) and an adequate hole mobility1. The record efficiencies for solar cells based on this material reached recently ~ 7.6% and 9.2% in a superstrate and substrate configuration respectively2,3. The most important problems affecting the development of devices based on Sb2Se3 are: difficulty to grow columnar grains, i.e. in the direction of the ribbons constituting the Sb2Se3 (along the c-axis) Low electrical values in terms of Voc, which represents the most critical parameter in this type of solar cells4.In this work we search for the best n-type partner layer forming the p-n junction with Sb2Se3. In fact, we believe that there is a strong correlation between the electrical parameters of the antimony selenide-based solar cells and the preferential growth direction of the grain forming the Sb2Se3film. We study experimentally the effect of using CdS, CdS:F [5], CdSe and As2S3 as window layer. We investigate the morphological characteristics of the Sb2Se3 film grown on those materials and the preferential growth direction through SEM, EDX, XRD and Raman analysis. Antimony selenide thin film is deposited using the close-spaced sublimation technique while the window layers are deposited by radio frequency magnetron sputtering. References 1. Mavlonov A et al 2020 A review of Sb2Se3 photovoltaic absorber materials and thin-film solar cells Sol. Energy 201 227–46 2. Wen X et al 2018 Vapor transport deposition of antimony selenide thin film solar cells with 7.6% efficiency Nature Comm. 92179 3. Li Z et al 2019 9.2%-efficient core-shell structured antimony selenide nanorod array solar cells Nature Comm. 10 1–9 4. F Ayala-Mató et al 2021 Semicond. Sci. Technol. 36 015016 5. N. Romeo, A. Bosio, V. Canevari 2003 The role of CdS preparation method in the performance of CdTe/CdS thin film solar cell. Proceedings of the 3rd World Conference on Photovoltaic Energy Conversion, vol. A, p. 469-470