Exploring AgBixI3x + 1 semiconductor thin films for lead-free perovskite solar cells

Perovskite solar cells are based on organolead halide compounds which are used as highly efficient solar cell absorber materials. However, their lead component is a high human health concern, toxic, and causes strong damages when disperse in the environment. In the present paper, silver iodobismuthate compounds are investigated as lead-free semiconductors in replacement of organolead halide in perovskite solar cells. We describe the design of thin films of AgBixI3x (+) (1) for x composition ranging between 1 and 2.25. The preparation is optimized to get well-crystallized well-covering layers. The prepared compounds are semiconductors, absorbing light below 700 nm. Compounds for x < 1.5 have a pure rhombohedral phase. Ag2Bi3I11 is crystallized in the pure cubic phase, yields to the layer with the largest grains and is the composition giving the best solar cell power conversion efficiency (PCE). For higher Bi content, a mixture of cubic AgBi3I11 and BiI3 is produced. The device design includes the use of a SnO2 hole blocking layer to get good efficiency. Based on these results it can be concluded that AgBixI3x (+) (1) compounds are potentially promising properties for application in optoelectronic devices. (C) 2017 Elsevier Ltd. All rights reserved.