Facile fabrication of PtNP/MWCNT nanohybrid films for flexible counter electrode in dye-sensitized solar cells

Abstract

A platinum nanoparticle/multi-wall carbon nanotube (PtNP/MWCNT) hybrid counter electrode (CE) based on a flexible substrate, Ti foil, was prepared for a high performance dye-sensitized solar cell (DSSC) via a facile fabricating route. This flexible nanohybrid CE was established by using a requisite homemade dispersant, consisting of poly(oxyethylene) segment and imide linkage functionalities. MWCNTs were well suspended in an ethanol/water solution in the presence of copolymer dispersant and PtNPs. The solution containing the PtNP/MWCNT (2/1 weight ratio) hybrid was further coated into a thin film on the Ti foil by the doctor blade technique, followed by annealing at 390 °C to obtain the flexible PtNP/MWCNT hybrid CE. The solar-to-electricity conversion efficiency (η) of a DSSC with the flexible PtNP/MWCNT hybrid CE gave a higher value of 9.04% in comparison to that of the cell with a conventional Pt CE (η = 7.47%). A rougher surface morphology of the nanohybrid film precisely controlled by the configuration of MWCNT was obtained, with reference to that of a Pt-sputtered film. The PtNP/MWCNT hybrid film was physically characterized by scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. Cyclic voltammetry, incident-photon-to-current efficiency, and electrochemical impedance spectra were examined for confirming the high electro-catalytic ability of this flexible PtNP/MWCNT hybrid CE.