Fabrication and characterization of silicon naphthalocyanine, gallium phthalocyanine and fullerene-based organic solar cells with inverted structures

Abstract

Fullerene/phthalocyanine solar cells with inverted structures were fabricated, and the photovoltaic properties, optical absorption and microstructrues were investigated. Silicon naphthalocyanine, gallium phthalocyanine, and poly(3-hexylthiophene) were used for donor materials, and 6,6-phenyl C61-butyric acid methyl ester was also used as an acceptor material. The solar cells with the inverted structure provided higher conversion efficiencies by addition of silicon naphthalocyanine, and had more stability compared to that with normal structure in the air. Nanostructures of the solar cells were investigated by transmission electron microscopy, which indicated the dispersion of nanocrystals in the active layers. Energy levels of the molecules were calculated, and a carrier transport mechanism was proposed.