Novel π-electron extension system via chromophores self-polymerization to enhance the NLO efficiency

A new strategy for the self-polymerization of chromophores is investigated to develop a 2,7-carbazole-based nonlinear optical (NLO) conjugated polymer with an increasing conjugation length of chromophores. Elongation of the conjugation-path length in chromophores has established engineering guidelines to enhance optical nonlinearity. Compared with the traditional synthesis of an NLO polymer, the chromophores should be well-designed at a limited conjugation spacer, and then incorporated into a polymer matrix. In this research, the pi-conjugation spacer of chromophores extended perpendicularly to the dipole of chromophores during the polymerization process. Furthermore, this study marks the first research of integrating the pi-electrons of chromophores and conjugated polymers. These conjugated backbones promote a bulk-polarization response, leading to large NLO coefficients.