Enhancing Blue Emission in Poly(N-vinylcarbazole): Synthesis, Functionalization with Anthracene, and Mitigation of Aggregation-Caused Quenching

Abstract

This study reports the synthesis and functionalization of poly(N-vinylcarbazole) (PVK) with anthracene units to enhance its blue photoluminescence properties. Structural and thermal analyses confirmed successful incorporation of anthracene moieties into the PVK backbone at an approximate 3:1 ratio of PVK repeat unit to anthracene. Photophysical characterization showed that anthracene-functionalized PVK (PVK–An) retained blue-region emission (432 nm), although with reduced emission efficiency due to π–π stacking interactions. Incorporating PVK–An into an inert poly(methyl methacrylate) (PMMA) matrix mitigated aggregation-caused quenching (ACQ), increasing the photoluminescence quantum yield (PLQY) from 0.5% to 28.9% in the optimized 70:30 wt % PMMA/PVK–An blend. Time-resolved photoluminescence (TRPL) analysis revealed that the emission in both neat PVK and PVK–An arises from two decay pathways, S1→ S0and S1* → S0, corresponding to singlet excimer states emissions, respectively. Notably, PVK–An exhibited reduced excimer formation, as indicated by shorter fluorescence lifetimes (τ1≈ 5 ns) and a lower contribution from the longer decay component (τ2≈ 15 ns, Rel. 54.80%) compared to pristine PVK (τ2≈ 25 ns, Rel. 74.33%). These findings demonstrate the synergistic benefits of side-chain engineering and morphological control in the design of high-performance blue-emitting polymers for OLED applications.