Regulating Deposition Pressures During Rapid Thermal Evaporation Processes to Enable Efficient Sb2 Se3 Solar Cells.

Sb2 Se3 solar cells deposited by rapid thermal evaporation (RTE) have drawn extensive attention owing to their compatibility with the commercial production line of CdTe solar cells and can be used to fabricate high-quality Sb2 Se3 films with high reproducibility. However, the deposition pressure during the RTE process has not been clearly explored, although it has a significant effect on the Sb2 Se3 film quality. A novel two-step deposition strategy is proposed that finely regulates the deposition pressure to improve the quality of Sb2 Se3 absorber layers, thereby improving the device performance of Sb2 Se3 solar cells. This novel method includes a rapid deposition process under a low pressure (5 mTorr) and an in situ annealing process under a relatively high pressure (200 Torr). The maximum power conversion efficiency (PCE) of Sb2 Se3 solar cells fabricated by two-step deposited approach is up to 8.12%. The PCE enhancement is attributed to the increased grain size, reduced grain boundaries, modified surface Fermi level gradient of the absorber layer, and improved defect performance. This innovative deposition technique is expected to benefit other low-melting-point metal sulfoselenides for solar cell applications.