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

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-1)Pb(n)I(3n+1) and Ruddlesden-Popper type (PEA)(2)FA(n-1)Pb(n)I(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)(2)PbI4 is stronger. Foster 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)FA(2)Pb(3)I(10) films than that in (PEA)(2)FA(2)Pb(3)I(10) 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.

Automated summary

Quasi-two-dimensional perovskites have unique excitonic properties and are promising materials for optoelectronic applications. However, the influence of organic spacer cations on the structural distortions and charge screening between perovskite layers is still not well understood. This study presents the carrier transport characteristics of Dion-Jacobson and Ruddlesden-Popper type perovskite layers. The results provide valuable insights for further tuning the optoelectronic properties of layered perovskite devices.