Interlayer‐Sensitized Linear and Nonlinear Photoluminescence of Quasi‐2D Hybrid Perovskites Using Aggregation‐Induced Enhanced Emission Active Organic Cation Layers

A concept of interlayer‐sensitized photoluminescence (PL) of quasi‐2D hybrid perovskite (PVK) with a π‐conjugated optically interacting organic cation layer is introduced and demonstrated. A rod‐shaped aggregation‐induced enhanced emission (AIEE) organic cation (BPCSA+), well fitted into the lattice size of 2D PVK layers, is designed and synthesized to prolong the exciton lifetime in a condensed layer assembly in the PVK. The BPCSA+ promotes the PL of this hybrid PVK up to 10‐folds from that of a non‐π‐conjugated organic cation (OA) 2D PVK. Notably, different from PL of OA 2D PVK, the increased PL intensity of BPCSA 2D PVKs with an increase of the BPCSA ratio in the PVK indicates a critical photon‐harvesting contribution of BPCSA. The films of BPCSA 2D PVKs are incredibly stable in ambient environments for more than 4 months and even upon direct contact with water. Additionally, due to the strong two‐photon absorption property of BPCSA, the BPCSA 2D PVK displays superior emission properties upon two‐photon excitation with a short wavelength IR laser. Thus, the AIEE sensitization system for quasi‐2D PVK hybrid system can make a drastic improvement in performance as well as in the stability of the PVK emitter and PVK based nonlinear optical devices. Quasi‐2D perovskite composed of 2D perovskite layers and π‐conjugated organic cation featuring aggregation‐induced enhanced emission character are presented. These perovskites exhibit highly promoted linear and nonlinear optical properties by interlayer sensitization from the organic layer to perovskite layer.