High efficiency and large optical anisotropy in the high-order nonlinear processes of 2D perovskite nanosheets

Zehong Chen,Zhang-Kai Zhou,Wenbo Zhang,Zhonghong Shi,Zixian Li

doi:10.1515/nanoph-2021-0789

Abstract

Abstract Nonlinear nanophotonic devices have brought about great advances in the fields of nano-optics, quantum science, biomedical engineering, etc. However, in order to push these nanophotonic devices out of laboratory, it is still highly necessary to improve their efficiency. Since obtaining novel nanomaterials with large nonlinearity is of crucial importance for improving the efficiency of nonlinear nanodevices, we propose the two-dimensional (2D) perovskites. Different from most previous studies which focused on the 2D perovskites in large scale (such as the bulk materials or the thick flakes), herein we studied the 2D perovskites nanosheets with thickness of ∼50 nm. The high-order nonlinear processes including multi-photon photoluminescence and third-harmonic generation (THG) have been systematically investigated, and it is found the THG process can have a high conversion efficiency up to ∼8 × 10−6. Also, it is observed that the nonlinear responses of 2D perovskites have large optical anisotropy, i.e., the polarization ratio for the incident polarization dependence of nonlinear response can be as high as ∼0.99, which is an impressive record in the perovskite systems. Our findings reveal the properties of high efficiency and huge optical anisotropy in the nonlinear processes of 2D perovskite nanosheets, shedding light on the design of advanced integrated nonlinear nanodevices in future.

Highlights

Due to the remarkable performances in frequency conversion, entanglement generation, photon detection, as well as the small size easy for integration, nonlinear nanophotonic devices have brought about great advances to the fields of nano-optics, integrated optics, quantum science, biomedical engineering, etc
It is observed that the nonlinear responses of 2D perovskites have large optical anisotropy, i.e., the polarization ratio for the incident polarization dependence of nonlinear response can be as high as ∼0.99, which is an impressive record in the perovskite systems
We obtained high quality 2D R–P phase perovskites (2D RPPs) single crystals (BA)2(MA)n−1PbnI3n+1 (n = 1, 2, 3, 4) by solution cooling crystallization (Figure S1, Supplementary Material), which were exfoliated mechanically into nanosheets down to several layers. 2D RPPs (BA)2(MA)n−1PbnI3n+1 possess Van der Waals structure (Figure 1a): [PbI6]4− octahedrons constitute the basic inorganic framework; short-chain amine MA+ occupy the voids of the inorganic layer and combine with [PbI6]4− octahedrons through ionic bonds, which form perovskite layers; long-chain amine n-BA+ forms spacer layers, which combine mutually by Van der Waals forces, n-BA+ and [PbI6]4− octahedrons combine by ionic bonds

Summary

Introduction

Due to the remarkable performances in frequency conversion, entanglement generation, photon detection, as well as the small size easy for integration, nonlinear nanophotonic devices have brought about great advances to the fields of nano-optics, integrated optics, quantum science, biomedical engineering, etc. Restricted by the requirement of subwavelength scale which offers the possibility for high integration, the size of material which generates the nonlinear process in nanophotonic device is usually very small, and its optical nonlinear response is relatively weak (comparing with bulk nonlinear material). This fact leads to the low efficiency of nonlinear nanodevices, greatly limiting their future applications and developments. The organic spacer layer A′ existing in 2D perovskites forms

Methods

Results

Conclusion