Nucleation‐Controlled Crystallization of Chiral 2D Perovskite Single Crystal Thin Films for High‐Sensitivity Circularly Polarized Light Detection

RESEARCH ARTICLE www.advmat.de Nucleation-Controlled Crystallization of Chiral 2D Perovskite Single Crystal Thin Films for High-Sensitivity Circularly Polarized Light Detection Lin Wang, Wei Hao, Boyu Peng, Jie Ren,* and Hanying Li* 2D Dion−Jacobson (DJ) chiral perovskite materials exhibit significant promise for developing high-performance circularly polarized light (CPL) photodetectors. However, the inherently thick nature of DJ-phase 2D perovskite single crystal limits their ability to differentiate CPL photons with the two opposite polarization states. In addition, the growth of DJ-phase perovskite single crystal thin films (SCTFs) has proven challenging due to the strong interlayer electronic coupling. Here, a nucleation-controlled strategy is employed to grow a novel DJ-phase perovskite [(R/S)-3APr]PbI4 [(R/S)-3APr = (R/S)-3-Aminopyrrolidine] SCTFs with large area, low thickness and hence high aspect ratios. Structural and photoluminescence analyses reveal that introducing the divalent organic cations into the perovskite framework reduce the interlayer distance, resulting in low exciton binding energy. This facilitates charge separation and transport. The resulting SCTF photodetector showcases excellent detection performance with anisotropy factor for photocurrent as high as 0.65, responsivity of 1.97 A W−1, detectivity of 5.3 × 1013 Jones, and 3-dB frequency of 2940 Hz, demonstrating its potential as a promising candidate for CPL-sensitive photodetectors. This novel approach, therefore, provides a framework for the growth of DJ-phase perovskite SCTFs and advances their applications in sensitive CPL photodetection. 1. Introduction Detection of circularly polarized light (CPL) is essential for nu- merous applications in chiral photonics, including quantum computation,[1] high-definition imaging,[2] biological science,[3] and security surveillance.[4] Conventional CPL photodetectors based on inorganic semiconductors lack intrinsic chirality and rely on multiple optics to discriminate the left- and right- handedness of the CPL (LCP and RCP). However, the increased system complexity poses challenges for modern integrated tech- nologies. In recent years, organic-inorganic halide perovskites L. Wang, W. Hao, B. Peng, J. Ren, H. Li MOE Key Laboratory of Macromolecular Synthesis and Functionalization International Research Center for X Polymers Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027, China E-mail: jie.ren@zju.edu.cn;hanying_li@zju.edu.cn The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202414199 DOI: 10.1002/adma.202414199 have emerged as promising candidates for optoelectronics due to their superior semi- conducting properties.[5] By incorporating chiral organic cations into lattices, inor- ganic perovskite skeletons were endowed with intrinsic chirality through asymmet- ric hydrogen-bonding interaction,[6] en- abling direct detection of CPL.[7–10] How- ever, the incorporation of relatively large chiral ligands into the 3D perovskite lat- tices is hindered by steric constraints.[11] Instead, (quasi-) 2D perovskite forms with an alternating arrangement of insulated organic spacers and conductive inorganic slabs.[12,13] Previous works have commonly ob- tained Ruddlesden-Popper (RP) type 2D perovskites,[14,15] where monovalent ligands constitute the bilayer organic spacer with interlayer Van der Waals (VDW) interac- tion. The organic spacer acts as a “po- tential barrier,” while the inorganic slab acts as “potential wells”.[16] This natural quantum well structure dictates anisotropic transport of charge carriers in the in-plane and out-of-plane directions.[17] However, photogenerated excitons are confined within the inorganic layer, making it difficult to achieve efficient charge transport across the inorganic layer along the out-of-plane direction. Furthermore, the dielectric constant mismatch between the inorganic layer and surro