Lead-free perovskite thin film solar cells from binary sources

The development of lead-free, all inorganic perovskites is a potential pathway to overcoming the stability limitations and the environmental hazards associated with the dominant organic/inorganic hybrid lead halide based absorber layers. As with all thin films solar cells, scalable roll-to-roll methods with broad processing windows are desirable. Here, we present promising initial materials and photovoltaic device results on vapor deposited CsGeI
₃
. The perovskite was fabricated by a simple anneal of stacked binary, metal-iodide, precursors. The resulting perovskite had an optical bandgap of 1.7 eV. An initial test device had an efficiency of 0.58%, and 445 mV V
_OC
.