Multilayer-Type Organic Solar Cells Using Phthalocyanines and Perylene Derivatives

Photovoltaic properties of multilayer-type organic thin film solar cells were investigated. Phthalocyanines (Pc) and perylene derivatives (PTC) shown in Fig. 1 were employed for p-type and n-type layers, respectively. The cell structure was Indium tin oxide (ITO)/PTC/ Pc/Au, and the cells were irradiated with white light through the ITO electrode. The thicknesses of organic layers were typically 500 Å. Positive voltages appeared on Au electrodes with photo-irradiation. Short-circuit currents of the cell were proportional to the light intensity of incident light, and open-circuit voltages were proportional to the log (light intensity). The wavelength dependence of short-circuit currents reflected the absorption spectra of both Pc and PTC layers, indicating the occurrence of effective carrier generation in both organic layers. Power conversion efficiencies of the cells ranged between 0.02 and 2.06% at the incident white light of 11.2mW/cm² (Tables 2 and 3). The highest power conversion efficiency was obtained in the ITO/H₂Pc/PV/Au cell, and the fill factor of the cell was 0.61. The major factors that determined short-circuit currents, open-circuit voltages, and fill factors were discussed.