THEORETICAL STUDY OF ONE- AND TWO-PHOTON ABSORPTION PROPERTIES OF ORGANIC CONJUGATED MATERIALS FOR PHOTOVOLTAIC DEVICES

摘要

In the process of photovoltaic energy conversion, photons with the energy below the band-gap can not be absorbed and do not contribute to energy conversion. Frequency up-conversion describes the conversion of low energy incident photons towards higher energy photons via active materials. Two-photon absorption induced fluorescence is one of the approaches that convert low energy incident photons towards higher energy photons via active material. In this paper, quantum-chemical techniques were applied to theoretically investigate one- and two-photon absorption properties of some new molecules with "A" shape. Two-photon absorption cross sections of these derivatives were obtained using three-state model. Geometrical structure of molecule was optimized using Hartree-Fock Theory (HF) and properties of excited states of molecule were obtained based on Configuration Interaction with single excitations method (CIS).