A novel carbon nanotube/polymer composite film for counter electrodes of dye-sensitized solar cells

In the development of optoelectronic and electronic devices, it is critically important, but remains challenging to discover new electrode materials to replace the conventional indium and platinum which have obvious disadvantages including high cost, complex fabrication, and chemical instability during the use. To this end, carbon nanotube (CNT)/polymer composite materials may represent one of the most promising candidates due to the combined advantages including high surface area, excellent electrical and electrocatalytic properties, and high stability from CNTs while good flexibility, abundant supply, and easy fabrication from polymers. In the current composite electrodes, however, CNTs are typically interconnected to form networks, and the generated charges have to hop through a lot of boundaries among CNTs. The resulting organic solar cells based on the CNT/polymer composite electrodes showed low efficiencies. Here we have developed a perpendicularly aligned and penetrated CNT/polymer composite film through a simple slicing technique. This novel composite film exhibits good transparency, high flexibility, excellent electrical conductivity, and remarkable electrocatalytic activity, and may be widely used for various electrode materials. As a demonstration, it was used as a counter electrode to fabricate dye-sensitized solar cells with high efficiency.