Author:
Cha Myoungsik,Otomo Akira,Torruellas William E.,Stegeman George I.,Beljonne David,Brédas Jean Luc,Horsthuis Winfried H.G.,Möhlmann Guus R.
Abstract
Molecular systems, in particular polymers, with π-electron donor-acceptor groups are becoming potential candidates in applications where large bandwidth and low costs are desired for electro-optical modulation of optical information. Di-Phenyl molecules including Disperse-Red-1 and Di-Amino-Nitro-Stilbene (DANS) embody most of the requirements in stability, high loading, processability and very large electro-optical figures of merit1. However little is known about their electronic structure represented by their excited state spectrum and responsible for their nonlinear optical response, for both second and third order. We present a complete spectroscopic study of the DANS molecular system and compare our theoretical predictions to the second order nonlinear spectrum and four third order nonlinear optical spectra of amorphous DANS side-chain polymers. In particular we can successfully explain shifts of the nonlinear spectrum compared to the linear absorption one by properly accounting for Frank-Condon type displacements2.