A High Surface Area Organic Solar Cell Prepared by Electrochemical Deposition

A new design of a high surface area solid state organic solar cell is presented. The solid cell consists of a PPEI/TiOPc junction deposited inside a nanoporous TiO2 electrode, utilizing its high surface area (where PPEI=Perylenebisphenethylimide and TiOPc=Titanylphthalocyanine). The deposition of the organic semiconductors was performed by a new electrochemical deposition method, which is based on a simultaneous ionic dissolution and electrochemical re-neutralization of the organic materials. Although the overall conversion efficiency of the solid state cell is low, the analogous wet cell, TiO2/PPEI/TiOPc electrode in contact with redox electrolyte mediator, shows a photoresponse throughout the PPEI spectrum. The efficiencies of the various processes of photocurrent generation were examined and the results suggest that all steps are efficient except the electron transfer from the PPEI to the TiO2. This limitation is attributed to a thin dipole layer formed during the electrodeposition process, which alters the relative energetics at the PPEI/TiO2 interface.