Contrasting Charge-Carrier Dynamics across Key Metal-Halide Perovskite Compositions through In Situ Simultaneous Probes

Metal-halide perovskites have proven to be a versatile group of semiconductors for optoelectronic applications, with ease of bandgap tuning and stability improvements enabled by halide and cation mixing. However, such compositional variations can be accompanied by significant changes in their charge-carrier transport and recombination regimes that are still not fully understood. Here, a novel combinatorial technique is presented to disentangle such dynamic processes over a wide range of temperatures, based on transient free-space, high-frequency microwave conductivity and photoluminescence measurements conducted simultaneously in situ. Such measurements are used to reveal and contrast the dominant charge-carrier recombination pathways for a range of key compositions: prototypical methylammonium lead iodide perovskite (MAPbI(3)), the stable mixed formamidinium-caesium lead-halide perovskite FA(0.83)Cs(0.17)PbBr(0.6)I(2.4) targeted for photovoltaic tandems with silicon, and fully inorganic wide-bandgap CsPbBr3 aimed toward light sources and X-ray detector applications. The changes in charge-carrier dynamics in FA(0.83)Cs(0.17)PbBr(0.6)I(2.4) across temperatures are shown to be dominated by radiative processes, while those in MAPbI3 are governed by energetic disorder at low temperatures, low-bandgap minority-phase inclusions around the phase transition, and non-radiative processes at room temperature. In contrast, CsPbBr3 exhibits significant charge-carrier trapping at low and high temperatures, highlighting the need for improvement of material processing techniques for wide-bandgap perovskites.

Automated summary

Metal-halide perovskites are versatile semiconductors for optoelectronic applications, but changes in composition can affect charge-carrier transport and recombination mechanisms. This study presents a novel technique to investigate these processes across a wide temperature range. The results show that the charge-carrier dynamics in different perovskite compositions are influenced by various factors, such as radiative processes, energetic disorder, and non-radiative processes.