Relation between Molecular Structures of Dyes and Photovoltaic Properties in Tow-Layer Organic Solar Cells Using Phthalocyanines and Perylenetetracarboxylic Acid Derivatives

Photovoltaic Properties of two-layer organic solar cells were investigated. Metal phthalocyanines (MPc) and porphyrins (Por) shown in Fig. 1 were employed for p-type layer. 3, 4: 9.10-Bis(imidazo[l, 2-a]pyrido-f used)perylene derivatives (PTCIz) shown in Fig. 2 were employed for n-type layer. The cell structure was indium-tin oxide(ITO)/n-type layer/ p-type layer/Au and the cells were irradiated with white light through the ITO electrode. The thicknesses of organic layers were 500 A. Positive voltage appeared on an Au electrode under illumination in all the cells. Short-circuit current was proportional to the incident light intensity (Fig. 9), and open-circuit voltage was proportional to the log (incident light intensity) (Fig. 10). The photocurrent spectra reflected the absorption spectra of MPc or Por layers, indicating the occurrence of effective carrier generation in MPc or Por layers. The short-circuit current of the cells ranged between 0. 89 and 0. 004 mA/cm² at the incident light power of 15 mW/cm² (Tables 1, 2 and 3). The open-circuit voltage ranged between 0. 74 and 0.15 V. The fill factor ranged between 0. 63 and 0. 21. Short-circuit current was most profoundly influenced, when chemical structures of dyes were varied. The energy conversion efficiencies of the cells using MPc and PTCIz ranged between 1. 9 and 0. 002%.