Dramatical enhancement of circular dichroism in chiral hybrid perovskites via carboxylic hydrogen bond engineering

Chiral hybrid perovskites (CHPs) have been regarded as promising candidates for developing chiroptoelectronics applications. However, circular dichroism (CD), as one of the most important characteristics to evaluate the chiroptical activity, remains at a comparatively low level in CHPs compared to other chiral materials, which hinders the successful applications of CHPs in state-of-the-art spin-polarization. Hence, exploring new methods for enhancing CD in CHPs is urgently needed and remains challenging. Herein, enhanced CD response has been successfully realized via constructing carboxylic hydrogen bonding in chiral-achiral mixed cations perovskites ( R/S -PPA) 2 (ABA)PbBr 5 ( 2R/2S ) (PPA = 1-phenylpropylamine, ABA = 4-aminobutyric acid). Compared with the prototype ( R/S -PPA)PbBr 3 ( 1R/1S ), 2R/2S provide intimate connections between organic units and inorganic parts via carboxylic hydrogen bonding N–H⋯O bridge, contributing new chirality transfer paths. A larger inorganic skeletons’ helicity in 2R/2S predicts a high degree of chirality transfer. Thus, 2R/2S exhibit significantly enhanced CD response with an anisotropy factor amplified by an order of magnitude. Finally, bright blue circularly polarized luminescence applications are achieved in 2R/2S . This work systematically investigates the correlation between CD and hydrogen bonding interaction in CHPs, meanwhile providing a new avenue to develop the application potential of chiral materials in chiroptoelectronics.