All-solution-processed small-molecule solar cells by stripping-transfer method

Copper phthalocyanine (CuPc) and zinc phthalocyanine (ZnPc) were both widely used in small-molecule solar cells which were considered as promising materials for photovoltaic technology. However, all-solution-processed CuPc (ZnPc)-based devices are not be fully studied. The low solubility of CuPc and ZnPc causes a bad morphology of CuPc (ZnPc)/C60 films, which leads to an unsatisfactory power conversion efficiency (PCE). In this work, in order to prepare continuous CuPc (ZnPc)/C60 composite films by solution processing, C60 film was transferred onto the CuPc (ZnPc) surface to form CuPc (ZnPc)/C60 films by stripping-transfer method. Scanning electron microscopic (SEM) images of the prepared CuPc/C60 and ZnPc/C60 composite films show both continuous films were formed because of stripping-transfer method. The performance of the small-molecule solar cells prepared by stripping-transfer method was better than devices prepared by the traditional evaporation method with a device structure of ITO/CuPc (ZnPc)/C60/Carbon paste. Due to the strong optical absorption of ZnPc, the efficiency of small-molecule solar cells using ZnPc is higher than devices using CuPc, and the efficiency could reach 1.37%. What is more, other composite films can also be formed by this low cost and convenient method, which is suitable for commercialized solar cells.