Fabrication of closed-space sublimation Sb2(S1-xSex)3 thin-film based on a single mixed powder source for photovoltaic application

Abstract Because of favourable stability, facile fabrication, non-toxicity, tunable bandgap and high extinction coefficient, Sb2(S1-xSex)3 combined the advantages of Sb2S3 and Sb2Se3 have attracted extensive attention. Unlike previous studies using a preformed target or source of a single composition, our study offered a high‐throughput closed-space sublimation method based on a single mixed powder source of Sb2S3 and Sb2Se3. We fabricated single-phase and highly crystalline Sb2(S1-xSex)3 films with strong (221) orientation, which is beneficial for the rapid transmission of photon-generated carriers. The bandgap of films evolved from 1.79 eV to 1.38 eV that accompany the varying x value of Se content from 0.14 to 0.85. The corresponding solar cells with the structure of FTO/CdS/Sb2(S1-xSex)3/Au were fabricated, and then the relationship between performance, source temperature and alloy composition were investigated. The open-circuit voltage and short circuit current density showed opposite trends with increased Se content. Finally, the champion device with a PCE of 2.70% was obtained employing Sb2(S0.25Se0.75)3 absorber, which had optimal grain orientation, favourable surface morphology. The bandgap is 1.45 eV, which falls into the ideal bandgap in the Shockley–Queisser limit. A low reverse saturation current density (2.35 × 10−5 mA/cm2) and the relevant diode ideality factor (1.38) were obtained, which implies favourable junction quality. The CSS technique is expected to improve production efficiency and promote Sb2(S1-xSex)3 solar cell commercial applications, worth further optimization.