Application of a CdS nanostructured layer in inverted solar cells

摘要

An inverted solar cell has been constructed by the growth of a CdS layer on an indium tin oxide (ITO)/glass substrate followed by spin-coating of organic poly(3-hexylthiophene): [6,6]-phenyl C61-butyric acid methyl ester (P3HT: PCBM) or a zinc phthalocyanine derivative (ZnPc-4R): PCBM composite layer and using a free-standing PEDOT: PSS composite film as the top electrode. It has been found that CdS plays the role of an electron-selective (hole-blocking) layer to rectify the electron flow from the P3HT: PCBM or ZnPc-4R: PCBM bulk heterojunction to the ITO electrode. By changing the morphology of the CdS layer from a textured continuous film to a nanowire array we demonstrate an improved collection efficiency of charge carriers due to the increased organic-inorganic interface area. Thus, a bifunctional role of the CdS nanostructured layer as a bottom electrode with better electron affinity than ITO and as a means to increase the interface for better electron collection from the organic active layer has been demonstrated.