Facile synthesis of open mesoporous carbon nanofibers with tailored nanostructure as a highly efficient counter electrode in CdSe quantum-dot-sensitized solar cells

A simple but very efficient reproducible approach was developed to fabricate novel mesoporous carbon nanofibers (MCNFs) with tailored nanostructure by using porous anodic aluminium oxide (AAO) membrane and colloidal silica as hard templates and phenolic resin as a carbon source. The as-prepared MCNFs with a channel diameter of ca. 200 nm reveal uniform one-dimensional (1D) nanofiber structure, created by the replication of the AAO template, and open interconnected spherical mesopores of ca. 30 nm in diameter embedded in the CNFs, mainly controlled by the particle size of the silica template. Due to their large mesopore size and volume, high specific surface area and unique nanostructure constituted by the 1D macro-scaled porous CNF and 3D interconnected mesopore structure, the MCNFs not only possess a large electrochemically active surface area, but also an open highway network favoring rapid electron transfer and fast mass transport. As a counter electrode in a CdSe quantum-dot-sensitized solar cell, the MCNF has demonstrated higher catalytic activity towards the reduction of polysulfide electrolyte and superior photovoltaic performance to its peers such as activated carbon (AC), hollow core/mesoporous shell carbon and ordered multimodal porous carbon, and the commonly used Pt electrode, revealing a fill factor of 0.60 and a power conversion efficiency of up to 4.81%. Excellent photovoltaic performance demonstrated by the MCNF suggests synergetic effects from the combination of 1D and 3D nanostructures.