Study of optical and electrical properties of organic thin films for photovoltaic applications

Abstract

The paper deals with the study of optical, electrical and dielectric properties of thin film organic materials suitable for the preparation of optoelectronic devices (e.g. photodiodes, phototransistors, photovoltaic cells). As active layers palladium phthalocyanine (PdPc[t-Bu]4), fullerene (acceptor material, PCBM) and their mixture (9 : 5 mass %) were used. Thin films were prepared by two methods: by spin coating (Chemat technology Spin Coater) and by material inkjet printing (Dimatix Materials Printer DMP-2800). UV-VIS spectroscopy and ellipsometry were used to study the optical properties. The paper also presents results of electrical and dielectric measurements. We found out that the properties of all structures prepared by spin coating depend on the rotational speed of spin coater, on the mode of solution casting (static, dynamic) and in the case of material inkjet printing they are too much influenced by the substrate. Samples prepared on the substrate at 60 °C showed a photovoltaic effect with fill factor about 0.25 and the conversion efficiency about 0.2 %.