Mesoporous carbon counter electrode materials for dye-sensitized solar cells: The effect of structural mesopore ordering

Abstract Highly ordered, ordered and disordered mesoporous carbons were prepared by an organic–organic self-assembly method with different molar ratios of formaldehyde to resorcinol (F/R) under the catalysis of citric acid. The mesoporous carbon synthesized with the F/R ratio of 2 possesses highly ordered pore system and large surface area, while the ones with the F/R ratio of 1 and 3 have an ordered and a disordered wormhole-like mesostructure, respectively. These three kinds of mesoporous carbons were utilized as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs) and the effect of structural mesopore ordering on the photovoltaic performance was investigated. The cell assembled with highly ordered mesoporous carbon CE showed an excellent energy conversion efficiency of 6.06%, which is comparable to the one with Pt CE (6.29%), whereas ordered mesoporous carbon and disordered mesoporous carbon CEs based cells exhibited relatively poor photovoltaic performance at the same testing conditions. The enhanced catalytic capability of highly ordered mesoporous carbon CE is intrinsically attributed to the straight channels of long-range highly ordered 2-D hexagonal mesopores, which accelerates the diffusion of redox species and facilitates the charge-transfer process. The synthesized highly ordered mesoporous carbon with outstanding catalytic activity could be an alternative to replace Pt for high-efficiency DSSC CE.