Photoelectrochemical oxidative polymerization of aniline and its application to transparent TiO2 solar cells

Quasi-solid-state transparent TiO2 solar cells using aniline oligomer as a hole conducting material and PEDOT on FTO as a counter cathode catalyst were newly developed. The pore of the nanoporous TiO2 layer was filled with aniline oligomer as a hole conductor through the in situ photoelectrochemical oxidative polymerization of aniline under photo-excitation of TiO2 layers. The best efficiency of 0.36% with high open circuit voltage 0.83 V was obtained under simulated 1-sun conditions even though the cells absorb only UV light, containing only 5% photon energy to the total in solar light. The photoelectrochemical synthesis of a conjugated polymer (p-type electron donor) is an effective way to fill the porous structure of inorganic n-type electron acceptor like nanoporous TiO2 and to obtain the molecular level contact between them.