Composition engineering to enhance the photovoltaic performance and to prolong the lifetime for silver bismuth iodide solar cell

Abstract

Lead, a toxic element in organometal halide perovskite solar cells, has caught lots of attention and has raised public concerns after such perovskite solar cells made rapid progress in their photovoltaic performance. Herein, a series of lead-free light absorber layers with a rudorffite structure were examined in this study. The obscure role of A-site and B-site cation in silver bismuth iodide rudorffite materials has been revealed through their energy diagrams and surface potential analyses. By manipulating the stoichiometric ratio of bismuth and silver at a ratio of 1.1/3, a Ag3BiI6 layer with uniform morphology, high carrier mobility, and a high light response was obtained. The superior optoelectrical properties of the modified Ag3BiI6 active layer directly influenced the photovoltaic performance and the environmental stability of such a device. The photovoltaic device with the modified Ag3BiI6 active layer exhibited a PCE of 2.60%. It also maintained over 80% of its initial PCE after being stored in an ambient environment for over 3,000 h. This result sheds light on how to process silver bismuth iodide materials and extends the knowledge for rudorffite materials.

Keywords

• Rudorffite
• Solar cell
• Silver bismuth iodide
• Lead-free
• Composition engineering, stability