In this paper, in order to study the relationship between structure and
performance, four new NFA derivatives were designed based on the two
reported NFA molecules BO-4Cl and BTP-S2 by replacing the BT unit with a
less-electron deficient BTz unit and inserting another ethylene double
bond between the central core and the terminal groups. The DFT and
TD--DFT calculations were applied to invstigate linear and nonlinear
optical properties, such as electronic structure, electronic absorption,
reorganization energy and the second-order NLO properties. The
investigation demonstrates that they are all narrow bandgap derivatives,
the absorption spectrum extends to the near-infrared region and using
two ethylene double bond is the most effective way to reduce the energy
gap, redshift the maximum absorption peak and the middle absorption
band, enhance hole transport ability and weaken electron transport
ability and enhance second-order NLO response. Considering the smaller
electron and hole reorganization energy and the larger static first
hyperpolarizability value, the studied NFA derivatives have great
potential to become ambipolar charge transport materials and large
second-order NLO materials.