Enhanced Red Phosphorescence of Purely Organic Formyl Compounds via Host-Guest Doping

Abstract

In this study, two aldehyde-functionalized derivatives, 4-(4-Pyridinyl)benzaldehyde (4PB) and 2-Hydroxy-1-naphthaldehyde (2HN), were designed and synthesized, leveraging the electron-deficient nature of aldehyde groups to modulate the molecular electronic structure and achieve pronounced red room-temperature phosphorescence (RTP). Through host-guest doping with phthalic anhydride (PA), we constructed doped luminescent materials exhibiting intense red RTP upon 365 nm excitation, characterized by an immediate bright afterglow upon excitation cutoff, a phosphorescence lifetime of up to 411 ms, and a visible duration exceeding 8 seconds. Time-dependent density functional theory (TD-DFT) calculations further revealed that triplet excitons are efficiently transferred from the host to the guest via a Dexter energy transfer mechanism, driving the guest phosphorescence. Additionally, the doped system exhibits excellent stability under extreme conditions, highlighting its potential for applications in complex environments.