Electron donor-acceptor complexes as potential high-efficiency second-order nonlinear optical materials. A computational investigation
- Northwestern Univ., Evanston, IL (United States)
The second-order nonlinear optical response of model molecular 1:1 and asymmetric 2:1 organic [pi] electron donor-acceptor (EDA) complexes is investigated using the INDO/S sum-over-excited particle-hole-states formalism. It is found that intermolecular charge-transfer transitions in EDA complexes represent a promising approach to achieving sizable second-order optical nonlinearities. Calculated hyperpolarizabilities may be generally related to the strength of the donor-acceptor interaction in the complex, affording for a given acceptor, the largest values in the case of aminoarene donors. The large change in dipole moment that accompanies intermolecular charge-transfer transitions and the relatively low-lying charge-transfer excitation energies are the major sources of the large calculated second-order nonlinearities. The relative orientation of donor and acceptor components is also an important feature, leading to stabilization of the ground state as well as to maximization of the oscillator strength of the lowest energy charge-transfer excitation and, in turn, the NLO response. In the case of asymmetric 2:1 EDA complexes, calculated hyperpolarizability enhancements over the 1:1 complexes can be related to the red-shift of the charge-transfer excitation as well as to an increase in dipole moment change between ground and excited states. The perturbation theoretical two-level' model is a useful first approximation for predicting the second-order nonlinear response of such complexes. 29 refs., 2 figs., 3 tabs.
- OSTI ID:
- 6568448
- Journal Information:
- Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 115:2; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360606* -- Other Materials-- Physical Properties-- (1992-)
42 ENGINEERING
426002 -- Engineering-- Lasers & Masers-- (1990-)
AROMATICS
CHARGE TRANSPORT
COMPLEXES
DIPOLE MOMENTS
EFFICIENCY
ENERGY LEVELS
EXCITED STATES
GROUND STATES
MATHEMATICAL MODELS
NONLINEAR OPTICS
OPTICAL PROPERTIES
OPTICS
ORGANIC COMPOUNDS
PERTURBATION THEORY
PHYSICAL PROPERTIES
RED SHIFT
STABILIZATION