High-throughput method to deposit continuous composition spread Sb₂(Se_xS_1 − x)₃ thin film for photovoltaic application

Sb₂(Se_xS_1 − x)₃ alloy materials with tunable bandgaps combining the advantages of Sb₂S₃ and Sb₂Se₃ showed high potential in low cost, non-toxicity, and high stability solar cells. The composition dependence of device performance becomes indispensable to study. However, traditional approaches often implement 1 composition at a time, which easily lead to long period and systematic errors. The present work developed a high-throughput experimental method, close-space dual-plane-source evaporation (CDE) method, to successfully deposit continuous composition spread Sb₂(Se_xS_1 − x)₃ library at 1 time. On the surface of the obtained film, the x value of Se content evolved from 0.09 to 0.84 by a series of complementary characterizations. At depth direction, the alloy film kept high crystallinity and composition consistency. Solar cell arrays (19 × 6) were fabricated to investigate the relationship between compositions and performances. As the increase of Se content, the conversion efficiency first increased from 1.8% to 5.6% and then decreased to 5%. The V_oc and J_sc demonstrated an opposite evolution trend. The champion device with the composition of Sb₂(Se_0.68S_0.32)₃ achieved the V_oc and J_sc trade-off exceeding the performances of Sb₂S₃ (2.43%) and Sb₂Se₃ (4.97%) devices. Cryogenic and transient characterizations were utilized to investigate the distinct performance evolution mechanism. There existed shallow defect levels in Se-rich alloys and deep defects in sulfur-rich ones. The widely tuned absorber compositions combined with distinct defect characters induced to the large variation of device performance. The present continuous composition spread Sb₂(Se_xS_1 − x)₃ film and their CDE fabrication technique were expected to efficiently screen materials and promote the development of antimony chalcogenide solar cells.