New Counter Electrodes Of Dye-sensitized Solar Cells

Dye sensitized solar cells (DSSCs) have attracted considerable interest as potential low-cost alternatives to conventional silicon-based solar cells. As one of the most important components in DSSCs, the noble metal platinum is widely applied as counter electrode (photocathode) due to its superior electrocatalytic activity, high electrical conductivity, as well as good chemical stability. In view of the limited reserve, identified resources and increasing price of the platinum in the word, it is of highly importance to seek low-cost and Pt-free counter electrode alternatives with a high electrocatalytic activity for future development of DSSCs.In this work, several low-cost materials were prepared as counter electrode for DSSCs. The electrocatalytic photoelectrochemical performance of I3-/I- couple with different counter electrode were investigated in detail. The major work is presented as following:(1) TiN as counter electrode for DSSCs. The highly ordered TiN nanotube arrays are successfully synthesized by the anodization and subsequent nitridation, and used as counter electrodes for DSSCs for the first time. In this work, we focus mainly on the electrocatalytic propertity of the different TiN materials in the electrolyte containing I3-/I- couple. In addition, the effect of the electrochemical and photovoltaic conversion performance of counter electrode for DSSC is analyzed in detail. It is demonstrated that TiN nanotube arrays have an obviously reducing charge-transfer resistance at counter electrode/electrolyte interface, and low ohmic internal resistance. Correspondingly, the DSSC using the TiN nanotube arrays as counter electrode have a comparable photovoltaic performance as compared with the one using the conventional FTO/Pt counter electrodes. This is a new strategy for developing the low cost counter electrode materials with electrocatalitic properties, similar to noble metal platinum.(2) The surface nitrided Ni as counter electrode for DSSCs. The surface nitrided Ni foil and particle film are prepared and investigated as high efficient and low-cost counter electrodes of DSSCs for the first time. It is monstrated that only a thin nitrided layer can be formed on the surface of the metallic nickel after the nitridation in ammonia, while the bulk phase still remains the stable metallic nickel structure. With such bifunctional structure, the surface nitrided foil and particle film present the high surface electrocatalytic activity and good electrical conductivity. Correspondingly, the enhanced photovoltaic performance is obtained for the surface nitrided Ni foil and particle film as counter electrode for DSSCs, which is competitive to the conventional and expensive FTO/Pt counter electrode. It is no doubt that the surface nitrided Ni is a potential low-cost alternative to the expensive noble metal Pt in future applications of DSSCs.(3) Mesoporous carbon arrays as counter electrode for DSSCs. Highly ordered mesoporous carbon arrays are prepared by a facile carbonization of the natural bamboo and oak wood in argon atmosphere. The as-prepared oak mesoporous carbon arrays have good electrocatalytic activity and high conductivity, based on their well connected framework, highly ordered microtexture, wider mesopores and larger surface area. Consequentially, the photovoltaic performance of the DSSC with the oak mesoporous carbon array film as counter electrode is excellent and comparable to that of the DSSC with FTO/Pt counter electrode. In addition, it is a simple method for a mass production of mesoporous carbon with oak woody raw materials.