Solution-processed solar cells based on environmentally friendly AgBiS2 nanocrystals

Solution-processed inorganic solar cells are a promising low-cost alternative to first-generation solar cells1, 2. Solution processing at low temperatures combined with the use of non-toxic and abundant elements can help minimize fabrication costs and facilitate regulatory acceptance. However, at present, there is no material that exhibits all these features while demonstrating promising efficiencies. Many of the candidates being explored contain toxic elements such as lead or cadmium (perovskites2, 3, PbS4, CdTe5, 6 and CdS(Se)7, 8) or scarce elements such as tellurium or indium (CdTe and CIGS(Se)/CIS9, 10). Others require high-temperature processes such as selenization or sintering, or rely on vacuum deposition techniques (Sb2S(Se)311, 12, 13, SnS14, 15 and CZTS(Se)16). Here, we present AgBiS2 nanocrystals as a non-toxic17, earth-abundant18 material for high-performance, solution-processed solar cells fabricated under ambient conditions at low temperatures (≤100 °C). We demonstrate devices with a certified power conversion efficiency of 6.3%, with no hysteresis and a short-circuit current density of ∼22 mA cm−2 for an active layer thickness of only ∼35 nm