Regulation of the luminescence mechanism of two-dimensional tin halide perovskites

Tianju Zhang,Jun Wang,Long Zhang,Hong Chen,Xianfeng Chen,Chaocheng Zhou,Ningning Dong,Jia Lin,Xuezhen Feng

doi:10.1038/s41467-021-27663-0

Abstract

Two-dimensional (2D) Sn-based perovskites are a kind of non-toxic environment-friendly luminescent material. However, the research on the luminescence mechanism of this type of perovskite is still very controversial, which greatly limits the further improvement and application of the luminescence performance. At present, the focus of controversy is defects and phonon scattering rates. In this work, we combine the organic cation control engineering with temperature-dependent transient absorption spectroscopy to systematically study the interband exciton relaxation pathways in layered A2SnI4 (A = PEA+, BA+, HA+, and OA+) structures. It is revealed that exciton-phonon scattering and exciton-defect scattering have different effects on exciton relaxation. Our study further confirms that the deformation potential scattering by charged defects, not by the non-polar optical phonons, dominates the excitons interband relaxation, which is largely different from the Pb-based perovskites. These results enhance the understanding of the origin of the non-radiative pathway in Sn-based perovskite materials.

Highlights

Two-dimensional (2D) Sn-based perovskites are a kind of non-toxic environment-friendly luminescent material
We note that the structural composition of the organic cationic layer can influence the defect state density and the exciton–phonon interaction[20], so we can vary the types of organic cationic layers and compare the effects of different cations on the luminescence properties and carrier dynamics of 2D Sn-based perovskites to distinguish how defects and phonon scattering affect the optical properties of materials, and furtherly reveal the difference in the factors affecting the luminescence properties between Sn-based and Pb-based perovskites
We find it is the deformation potential scattering by charged defects, not by the optical phonons, that dominates the interband exciton relaxation, leading to an increase in the proportion of non-radiative relaxation of photogenerated carriers, for the 2D Sn-based perovskite materials

Summary

Introduction

Two-dimensional (2D) Sn-based perovskites are a kind of non-toxic environment-friendly luminescent material. We reduced the defect density in PEAI-rich to improve the PLQY of the PEAI-rich to 2.2% (Fig. 5c), and we found that the occupancy ratio and relaxation rate of component I of the band-edge exciton relaxation processes in the PEAI-rich sample were significantly lower than those of the (PEA)2SnI4 sample (Fig. 5d).

Results

Conclusion