Lead-free, stable, and effective double FA4GeIISbIIICl12 perovskite for photovoltaic applications

Abstract

Organic-inorganic hybrid lead halide perovskite solar cells emerge as a breakthrough photovoltaic technology with high power conversion efficiency. However, some inherent shortcomings impede their further industrialization: 1) the toxicity of Pb, 2) unstable, sensitive to moisture and/or light. To circumvent these issues, we study the lead-free and solution-processed photovoltaic devices based on the double-metals <111>-oriented 2D layered formamidinium germanium-antimony halide perovskites (FA4GeIISbIIICl12) in this contribution. Compared with benchmark MAPbI3, the larger formamidinium is selected to replace methylammonium to form a more stable crystal structure while the double metals germanium-antimony (GeII-SbIII) are chosen to replace Pb under the considerations that expanding the possible metal combinations in the design of new perovskite with analogous photovoltaic performance. The FA4GeIISbIIICl12 perovskite behaves as a stable and efficient semiconductor with direct bandgap of ~ 1.3 eV and its conductivity is one order of magnitude higher than that of MAPbI3. Meanwhile, FA4GeIISbIIICl12 based solar cell with power conversion efficiency up to 4.7% can be achieved without use of any additives. This approach opens up new possibilities of exploiting lead-free perovskite that incorporates metals in different valence states and offers great potential application in photoelectric field.