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

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, S(1) → S(0) and S(1)* → S(0), corresponding to singlet excimer states emissions, respectively. Notably, PVK-An exhibited reduced excimer formation, as indicated by shorter fluorescence lifetimes (τ(1) ≈ 5 ns) and a lower contribution from the longer decay component (τ(2) ≈ 15 ns, Rel. 54.80%) compared to pristine PVK (τ(2) ≈ 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.