Characteristics of dye-sensitized solar cells with surface-modified multi-walled carbon nanotubes as counter electrodes

A polystyrene-based functional block copolymer is employed as a surface modifier for multi-walled carbon nanotube (MWCNT) paste utilized in the fabrication of a MWCNT counter electrode (CE) in dye-sensitized solar cells (DSSCs). The surface modification of MWCNTs paste improves the dispersibility of MWCNTs, resulting in a facilitated fabrication of electrodes through the screen printing procedure, as evidenced by a lower viscosity and more homogeneous paste, as well as a more uniform MWCNT coating. Upon removing organic compounds from the paste through a thermal treatment procedure, the DSSC with the modified CE exhibits enhanced solar energy conversion efficiency (eta) compared with that of the neat MWCNT CE. The behavior stems from an improvement in the overall redox reaction kinetics and the short-circuit current (J(sc)) of the DSSC. The DSSC also exhibits an improved eta value over an extended storage period, which demonstrates a successful combination of processability, performance, and stability of the DSSC achieved by using an optimum amount of surface modifier for MWCNTs.