Substituent-dependent modulation of stability and electrochromism in perylene-conjugated radical ions

Abstract

Stabilizing reactive radical ions for practical use under harsh conditions remains challenging. Here, we effectively screen electroactive perylene-conjugated dyads (Peri–DPA(R))^0/˙+/˙−, where R represents substituent groups (CN, F, Me, and OMe), for their distinctive visible-region absorption, high stability without spectral degradation, and reversible redox behavior with electrochromism. Notably, radical cations (Peri–DPA(R)˙⁺) demonstrate superior stability and redox reversibility by combining D–A architecture, spin delocalization, and enhanced aromaticity, with performance improving as the electron-donating ability of the substituents increases. Theoretical calculations further reveal that redox-induced structural changes increase electron density toward the perylene π-system, facilitating favorable delocalization of the unpaired electron in the radical cations.