Optimization of donors, acceptors and bridges for novel organic electro-optic materials

Abstract

The effects of different donors, acceptors, and electron bridges on various properties of novel organic electro-optic materials are investigated. We synthesized and systematically researched 12 chromophores with different donors including alkylaniline, bis(4-piperidinyl)phenyl, bis(N,N-diethyl)aniline, and julolidine derivatives and acceptors including tricyanofuran (TCF) or phenyl-trifluoromethyl-tricyanofuran (3F-TCF) and pentafluorobenzene-tricyanofuran (5F-TCF) linked together via isophorone derivatives as the bridges. We tested the thermodynamic characteristics, photophysical properties, DFT theoretical calculations, and electro-optical properties of 12 chromophores to summarize the relationship between the chromophore structure and performance. The results indicate that not the strongest donor pairs with the strongest acceptors exhibit the best performance, for example, chromophores C5 and D5 with strong bis(N,N-diethyl)aniline and julolidine donors exhibit the highest electro-optic coefficients (245 and 228 pm V⁻¹), while they only modify with relatively weaker 5F-TCF acceptors. For weak alkylaniline, bis(4-piperidinyl)phenyl donors, the 3F-TCF acceptor can achieve the maximum electro-optic coefficient (151 and 189 pm V⁻¹).