Enhancing Circular Dichroism in Chiral Perovskites via Dual Spacer Cation Engineering for Circularly Polarized Light Detection

Abstract

Chiral hybrid organic-inorganic perovskites (HOIPs) have garnered considerable research interest in the field of optoelectronics, owing to their ability to integrate outstanding optoelectronic characteristics with distinct chiral or spin-related properties. Although recent years have witnessed the rapid development of chiral perovskites, methods for producing perovskites with high absorption dissymmetry factors (gCD) enabling polarization-resolved chiroptical applications are still lacking. This study introduces a strategic combination of dual spacer cations, i.e., achiral hexane-1,6-diammonium (HDA) and chiral 1-(chlorophenyl)ethylammonium (ClPEA), for boosting the chiroptical performance of 2D lead iodide HOIPs. Interestingly, ortho-ClPEA, incapable of forming 2D HOIPs independently, successfully creates 2D structures in collaboration with HDA, exhibiting CD signals aligned with the absorption characteristics of 2D HOIPs. This significant milestone leads to an outstanding gCD value of 0.018, positioning it among the top performers in the field of lead-based HOIPs. Furthermore, this study demonstrates the fabrication of circularly polarized light (CPL) detectors with a photocurrent dissymmetry factor (gIph) of 0.12, utilizing the HOIPs with enhanced chiroptical activity. Introducing dual spacer cations enhances circular dichroism (CD) in chiral perovskites. Substituting a portion of hexane-1,6-diammonium with chiral 1-(chlorophenyl)ethylammonium, featuring distinct chlorine atom placements, unveils diverse levels of CD enhancement. Notably, the chiral cation featuring an ortho-position chlorine achieves the highest absorption dissymmetry factor of 0.018. Films derived from this configuration exhibit a remarkable performance in circularly polarized light detection. image