Stable 6%-efficient Sb2Se3 solar cells with a ZnO buffer layer

Sb2Se3, a binary compound containing non-toxic and Earth-abundant constituents, is a promising absorber material for low-cost, high-efficiency photovoltaics. Current Sb2Se3 thin-film solar cells use toxic CdS as the buffer layer and suffer from unsatisfactory stability. Here we selected ZnO as the buffer layer and constructed superstrate Sb2Se3 solar cells with a certified power conversion efficiency of 5.93%. Randomly oriented ZnO produced by spray pyrolysis induced the growth of Sb2Se3 with preferred [221] orientation, and hence resulted in devices with fewer interfacial defects and better efficiency. Moreover, our unencapsulated device survived the stringent damp-heat (85 ∘C, 85% humidity, 1,100 h), light-soaking (50 ∘C, 1.3 sun, 1,100 h), thermal cycling, and ultraviolet preconditioning tests. The combined features of stability, Earth-abundant constituent and potentially low-cost manufacturing highlight the great potential of Sb2Se3 solar cell as a possible non-toxic alternative to CdTe photovoltaics. Thin-film photovoltaic devices are often based on toxic or rare materials. Here, Wang et al. grow oriented Sb2Se3 thin film on a ZnO buffer layer, and fabricate solar cells with a certified 5.9% conversion efficiency and which pass harsh stability tests under humidity, heat and illumination.