ZnO double layer film with a novel organic sensitizer as an efficient photoelectrode for dye–sensitized solar cells

Abstract A novel organic sensitizer, coded CR147, is applied to sensitize a ZnO–based dye–sensitized solar cell (DSSC). The common problem of ZnO dissolution and Zn 2+ /dye agglomeration, caused by the use of ruthenium–based dyes, is solved by the application of this CR147 dye. The highest power conversion efficiency ( η ) of 4.77% is achieved for the DSSC using a photoanode with a film of commercial ZnO nanoparticles (C ZnO) and the CR147 dye, while the η is only 3.41% for the DSSC with the commercial N719 dye. The cell performance with the CR147 dye is further improved by using a photoanode with the double layer ZnO film (D–ZnO), composed of an underlayer with coral–like ZnO nanocrystals and an overlayer with hexagonal club–like ZnO submicrocrystals. The DSSC with the D–ZnO film exhibits an η of 6.89%, which is ca. 45% higher than that of the DSSC with the C ZnO film (4.77%). This higher efficiency is attributed to the superior charge transfer and light–scattering abilities provided by coral–like ZnO nanocrystals and hexagonal clubs–like ZnO submicrocrystals, respectively, with reference to these parameters of C ZnO.