Effect of formamidinium (FA) ions on mixed 'A'-site based bromide perovskite (APbBr3) thin films

Hybrid organic-inorganic perovskites (HOIPs) have become promising candidates for future photovoltaics (PV) with significant advancements in their performance over recent years. Along with PV, HOIPs possess applications in photodiodes, photodetectors, photocatalysis, and memory devices. Generally, perovskites are structurally flexible to accommodate various cations on their respective sites through compositional engineering, thereby altering the characteristic material properties of the system. HOIPs have ABX(3) structures, in which organic or inorganic moieties occupy the monovalent 'A' site. In this work, the effect of formamidinium (FA) on the optical and morphological properties of HOIPs using two different bromide perovskites - FA(0.5)MA(0.4)Cs(0.1)PbBr(3) and MA(0.9)Cs(0.1)PbBr(3) - is examined. After 'FA' modification, we noticed a reduction in the bandgap and an increase in the grain size of the FA(0.5)MA(0.4)Cs(0.1)PbBr(3) perovskite compared with the MA(0.9)Cs(0.1)PbBr(3) perovskite. As a result, a better photocurrent response during photoelectrochemical analysis and an improved power conversion efficiency (PCE) for photovoltaic devices were detected with the FA-modified HOIP (FA(0.5)MA(0.4)Cs(0.1)PbBr(3)).

Automated summary

Hybrid organic-inorganic perovskites (HOIPs) have shown significant advancements in their performance in recent years and have great potential for applications in photovoltaics (PV) as well as other fields. This study investigates the effect of formamidinium (FA) on the optical and morphological properties of bromide perovskites, and finds that FA modification leads to a reduction in bandgap and an increase in grain size, resulting in improved photocurrent response and power conversion efficiency (PCE) for the FA-modified HOIP.