Photo-Crosslinked Electro-Optic Polymers Based on Carbene Insertion Reactions

Organic electro-optic (OEO) materials offer exceptional potential for high-speed, low-power photonic applications due to their large electro-optic (EO) coefficients and ultrafast modulation response. However, practical deployment is hindered by thermal relaxation of chromophore orientation, leading to performance degradation under elevated temperatures. Thermal crosslinking strategies, commonly used to enhance stability, often rely on Click chemistry that requires high temperatures (≥150 °C) and extended processing times (typically ≥2 h), which can cause film cracking, increased leakage current, and reduced device yield. To address these limitations, a rapid, room-temperature photo-crosslinking strategy is reported using nitrophenyl diazo ester (nitroPEDAz) units. Upon exposure to low-intensity UV-visible light (350-450 nm), nitroPEDAz decomposes to generate reactive carbene intermediates that insert into saturated C─H bonds, forming a dense and stable covalent network within 6 min. The absorption profile of nitroPEDAz is well-aligned with the optical window of EO chromophores and indium tin oxide (ITO), minimizing spectral competition. The resulting films exhibit enhanced thermal and mechanical robustness. For example, a JRD1/PHJ-145 composite (25 wt.%) shows a T_g (glass transition temperature) of 177 °C and retained >99% EO activity after 500 h at 85 °C. This strategy provides a universal, fast, and process-friendly solution for stabilizing high-performance OEO materials in integrated photonic devices.