Discussion of Photovoltaic Mechanisms of Organic Semiconductor Solar Cells; 有機半導体太陽電池の発電機構に関する一考察;

摘要： We have studied photovoltaic mechanisms of an organic solar cell using phthalocyanine for a p-type semiconductor and fullerene C60 for an n-type semiconductor in quantum chemistry simulation. This study examines computation of the electronic state of the phthalocyanine–fullerene C60 bimolecular system in the ground state by the DFT method using long-range corrected hybrid functional CAM-B3LYP. Some double bonds in unimolecular phthalocyanine become semi-double bonds in the bimolecular system. Furthermore, some carbon atoms in a fullerene molecule are negatively charged in the bimolecular system. These results suggest the generation of positive holes and conduction electrons in the bimolecular system. Investigation of reports about simulation in an excited state and the actual measurement of electric conductivity has revealed that these positive holes and conduction electrons in the ground state facilitate the migration of positive holes and conduction electrons generated in a photoactive layer by light irradiation.