Computational study of steric effects on the optical properties of oligomers

The optical properties of a variety of copolymer structures and their derivatives are determined from semi-empirical quantum chemical calculations. Possible candidates are found for organic light emitting diode and thin photovoltaic film applications. The largest blue shifts in the absorption spectrum are seen for derivatives that cause the oligomers under consideration to deviate from their unsubstituted planar configurations. This is primarily predicted to occur in systems with large steric interactions. Optical emissions are also predicted based on time dependent density functional calculations of excited states of these materials optimized with configuration interaction Hartree-Fock methods.