Application of single walled carbon nanotubes as counter electrode for dye sensitized solar cells

An effective counter electrode (CE) was prepared with single-walled carbon nanotubes (SCNTs) for the dye sensitized solar cells (DSSCs) by simple casting technique using polyvinylpyrrolidone (PVP) as a wrapping agent. The uniform and smooth SCNTs thin film without breaking of tubes were obtained on the fluorine doped tin oxide (FTO) glass substrate by the wrapping of PVP. The SCNTs and carbon residue composite were formed after the calcinations of SCNTs-PVP on FTO glass, which decreased the resistance of the electrode and promoted the higher electrochemical reaction for charge transfer reactions. DSSCs fabricated with SCNTs-PVP CE presented reasonably high conversion efficiency of 4.5% with high open circuit voltage (V_OC) of 0.718 V, short circuit current (J _SC) of 12.14 mA/cm² and fill factor (FF) of 51.7%, while the bare SCNTs CE showed the conversion efficiency 2.34% with V_OC 0.680 V, J_SC 13.7 mA/cm² and FF 26%. The improved photovoltaic performance of DSSC attributed to the high electrocatalytic activity for the reduction of I₃^- ion at SCNTs-PVP CE, resulting from the large R_CE and low R_CT of DSSC.