Highly efficient all solid state dye-sensitized solar cells by the specific interaction of CuI with NCS groups

Abstract

Highly efficient all solid state dye-sensitized solar cells (DSSC) were fabricated by the specific interaction of CuI with the NCS groups of the dye molecules and that of the counter electrodes. The counter electrode containing NCS groups was prepared by coating the PEG solution containing NCS groups. The counter electrode was connected with the NCS groups of the dye molecules by CuI. The specific interaction between the CuI with the NCS groups of the dye molecules and that of the counter electrode could lower the impedance of the interfaces, and facilitate the injection of the hole into the counter electrode to give the highly efficient all solid state DSSC. The specific interaction was investigated by X-ray photoelectron spectroscopy. The performance was improved by introducing PEDOT layer between the interface of FTO and the PEG containing NCS groups. The improvements are due to the reduction of the junction resistance across the interface in the presence of interlayer, which result in improved hole injection. The DSSC were stable and exhibited high efficiency (4.2%). They could be manufactured with inexpensive and low quality materials, and the practical use is promising.