Preparation of FTO-free and Coal Based Carbon Counter Electrodes for Dye Sensitized Solar Cells

The coal-based carbon counter electrodes (CEs) with low-cost and high-performance were prepared from different coal powders such as gas coal, coking coal and lean coal, and they were used to substitute both conductive glass substrate and catalyst layer. The effects of impregnation and surface modification of the coal-based carbon CEs on their structure and photovoltaic performance were investigated. XRD, SEM and electrochemical impedance spectroscope were used to character the structure and performance of coal based carbon CEs. Results show that the coal based carbon CE after impregnated is the integrative CE with porous top surface and dense bottom. The solar cell with coal based carbon CE with surface modified demonstrates high photovoltaic performance with open circuit photo-voltage (Voc) of 0.79 V, short circuit photocurrent density (Jsc) of 13.48 mA/cm2, fill factor (FF) of 0.67, and solar-to-electricity conversion efficiency (η) of 7.16%, which is 30% higher than that of the cell with graphite electrode, and comparable to that of the cell with Pt electrode. The results indicate that the as-prepared coal based carbon CE is a promising CE candidate for substitute conventional?Pt/FTO counter electrode.