Improvement of the performance of particulate phthalocyanine photovoltaic cells by the use of polar polymer binders

Effects of binder polymers on the performance of phthalocyanine photovoltaic cells have been investigated. The cells were fabricated by dispersing metal-free phthalocyanine fine particles in a binder polymer and sandwiching them between aluminum and In2O3 electrodes. Polymers such as poly (vinylidene fluoride), poly (vinyl fluoride), polyacrylonitrile, poly (4-vinylpyridine), poly (p-vinyl phenol), and poly (vinylidene chloride) were found to give a larger photocurrent and a higher conversion efficiency than did others. This is attributable to the enhancement of exciton dissociation due to a large electric field formed by the presence of polar groups in these polymers. An estimation based on a simple assumption showed that an electric field as high as 106 V/cm may be produced in the microenvironment of a photoactive site, strong enough to induce such an effect.