Enhancement of electro-optic activity by introduction of a benzyloxy group to conventional donor-π-acceptor molecules

In this work, we investigated the enhancement of the electro-optic response by introducing benzyloxy group as an additional donor part on conventional donor-pi-acceptor molecules. This new type donor exhibited a strong solvatochromic effect, indicating an extra donation to the pi-conjugated bridge, which shifted the charge-transfer absorption of the chromophores to the lower energy region. Furthermore, the simple modification on the donor moiety resulted in about 2-fold improvement in the first hyperpolarizability and macroscopic electro-optic coefficient (r(33)) over the benchmark 2-dicyanomethylen-3-cyano-4-{2-[E-(4-N,N-di(2-acetoxyethyl)-amino)-phenylene-(3,4-dibutyl)thien-5]-E-vinyl}-5,5-dimethyl-2,5-dihydrofuran (FTC) counterparts. An r(33) above 100 pm/V is ultimately achieved in conventional guest-host system. (C) 2011 Elsevier B. V. All rights reserved.