Selective preferred orientation for high-performance antimony selenide thin-film solar cells via substrate surface modulation

Antimony selenide (Sb 2 Se 3 ) has rapidly emerged in the field of photovoltaics with one-dimensional crystal structure. However, the power conversion efficiency (PCE) of Sb 2 Se 3 solar cells is influenced by the orientation of the Sb 2 Se 3 photoactive layers. In this study, we investigate the influence of substrate properties on the preferred orientation and microstructure of Sb 2 Se 3 films systematically. With the rise of substrate surface temperature and the decline of substrate surface bonding energy, the preferred orientation of the Sb 2 Se 3 films altered from (hk0) to (hk1) and finally to (002). After summarizing the performance of different preferentially oriented Sb 2 Se 3 solar cells, the results showed that the (hk0)-preferentially oriented devices exhibited a poor performance of less than 1.1 %. As the preferred orientation of Sb 2 Se 3 absorbers changed from (hk0) to (hk1), the carrier transport changed from inter-ribbon charge hopping to transportation along the (Sb 4 Se 6 ) n ribbons. This enhanced the carrier transport efficiency, thereby leading to the enhancement of the PCE to 2–3 %. Furthermore, when the (002) texture coefficient (TC) of the Sb 2 Se 3 films was between 1.8 and 3.6, the PCE of the devices was further enhanced to above 3.5 %. A maximum PCE of 4.79 % can be obtained when the (002) TC was 3.24. This study reveals the relationship between the Sb 2 Se 3 film preferred orientation and device performance, and demonstrates an effective way to precisely control the Sb 2 Se 3 film microstructure to obtain a high PCE.