Carrier dynamics in two-dimensional perovskites: Dion–Jacobson vs. Ruddlesden–Popper thin films

Abstract

Quasi-two-dimensional perovskites have emerged as candidates of high-performance materials for various optoelectronic applications due to the unique excitonic properties in their multilayer structures. Both Dion–Jacobson perovskites and Ruddlesden–Popper phases are attracting extensive interest due to their sudden evolution as efficient light-emitting, solar cell, and photocatalytic materials. However, the organic spacer cations between the halide perovskite layers tend to influence the structural distortions and interlayer charge screening, giving rise to a static effect, which impacts the carrier dynamics and is complex and remains elusive. Here, the study of carrier transport in Dion–Jacobson perovskite (PDMA)FA_n−1Pb_nI_3n+1 and Ruddlesden–Popper type (PEA)₂FA_n−1Pb_nI_3n+1 layers are presented by combining steady-state absorption, photoluminescence, and femtosecond time-resolved transient absorption spectra. The results show pure phase perovskite (PDMA)PbI₄ has a shorter hot electron relaxation time, and the carrier recombination of (PEA)₂PbI₄ is stronger. Föster resonance energy transfer in thicker (n = 3) layers is observed up to 2 ps after excitation; we attribute this to the short-distance transfer of excitons to neighboring perovskite sheets of higher order. There are more efficient exciton-transfer from two-dimensional phases to a three-dimensional-like phase in (PDMA)FA₂Pb₃I₁₀ films than that in (PEA)₂FA₂Pb₃I₁₀ films. These results provide valuable information on the carrier dynamics which would be utilized to further tune strategically the optoelectronic properties for devices based on layered perovskites.