Towards an understanding of structure-nonlinearity relationships in triarylamine-based push-pull electro-optic chromophores: the influence of substituent and molecular conformation on molecular hyperpolarizabilities

Abstract

We calculated the second-order hyperpolarizability (b) of a series of triarylamine (TAA) based donorbridge-acceptor (D-p-A) push-pull type nonlinear optical (NLO) chromophores with different electron donor moieties and the same thiophene p-bridge and dicyanovinyl electron acceptor using a timedependent Hartree-Fock (TDHF) approach within the software package MOPAC 2012. NLO chromophores with various quantities and positions of methoxy groups in the TAA donor moiety were investigated. The relationship between NLO properties and the electronic or geometric structures of the TAA donor subunit is discussed through the calculation results. Both substituent and conformational effects affect the delocalization of the nitrogen lone pair into the aryl rings, leading to a dramatic influence on the nonlinear optical properties. Introduction of methoxy groups at the ortho positions of the TAA moiety has a larger influence on the molecular hyperpolarizability and dipole moment than the introduction of methoxy group at the para or meta positions. Our calculation results demonstrate how to improve the NLO properties of TAA based chromophores while meeting practical device requirements. ; Fax: +1 972 883 2925; Tel: +1 972 883 5323 † Electronic supplementary information (ESI) available: All input les of model chromophores and all calculation results. See

Triphenylamine and some of its derivatives as versatile building blocks for organic electronic applications

“…The effects of substituents (Fig. (a)) on the HOMO–LUMO levels, ionization potentials and the molecular geometry of TPA have been widely investigated through the years . Electron‐donating groups such as amino or alkoxy substituents in the para position of TPA induce an increase of the HOMO and a decrease of I p .…”

Fluorescent vinyl and styryl coumarins: A comprehensive DFT study of structural, electronic and NLO properties

“…Organic molecules with nonlinear optical (NLO) properties have wide range of applications because of their small dielectric constants, 1 electro-optical (EO) modulation characteristics, 2 ultrafast responses, 3 high optical damage thresholds, simple methods of preparation and low fabrication costs. [4][5][6][7] The π-π * transitions in organic molecules make them better candidates as NLO materials for wide bandwidth optoelectronic telecommunication systems in electronic/photonic integrated circuits, phased array radars, and in terahertz (THz) and spectroscopy applications. 8,9 Unlike geometric perturbations of central metal ion occurring in the crystalline inorganic NLO materials the electronic charge transfer across the organic molecules plays a key role 10,11 allowing the optical response of NLO-active organic compounds much faster over the inorganic compounds.…”

Auxiliary donor for tetrahydroquinoline-containing nonlinear optical chromophores: enhanced electro-optical activity and thermal stability

“…In the past decades, many studies on NLO chromophores have mainly focused on the design of electron bridges and electron acceptors, while the donor units have remained relatively unchanged. 16,17 Some studies have shown that by introducing additional electron-rich heteroatom group into the donor moiety could effectively enhance nonlinear optical property. 12,15 Many works were focused on the optimization of these two donor groups by different kinds of modification.…”