2017 Volume 16 Issue 5 Pages 144-146
Recently, renewable energy is attracting attention globally. In Japan today, there is a shift with growing momentum to photovoltaic power generation from thermal power generation, which has heretofore served as the foundation of electrical power generation. We are studying improvement of the photovoltaic conversion efficiency of bulk heterojunction organic thin film solar cells and are preparing a device that requires detailed elucidation of its electronic properties and its mechanism of power generation. Accordingly, we have conducted quantum chemical calculations using a molecular pair of phthalocyanine and fullerene C60 employed as a specimen. Specifically, we have computed charge densities and electron clouds in the ground state while varying the molecular distance to 12 Å and 24 Å using the density functional method. Results demonstrate quite high negative charge density in C atoms near phthalocyanine in C60 when the distance between the two molecules is decreased to 12 Å, with a positive charge density in C atoms on the opposite side of phthalocyanine in C60. Results suggest that many conduction electrons and positive holes, the so-called carriers, are generated in the phthalocyanine − fullerene C60 bimolecular system when the molecular distance is decreased to 12 Å.
