Charge Transfer Between Polypyrrole Coated n-Si Electrodes And Solid Polymer Electrolytes

Abstract

Abstract We have developed photoelectrochemical cells based on rectifying junctions between n-Si and thin film polymer solid electrolytes. We describe various surface modifications applied to the n-Si electrodes which overcome a high activation energy barrier for efficient charge transfer to redox ions in the polymer solid electrolytes. Solvent free solid polymer electrolytes represent an important new class of ionically conducting materials (1). Their compatibility with thin film technology makes them potential candidates for a wide variety of technological applications. We have developed a new type of photoelectrochemical cell (PEC) based on rectifying junctions between semiconductor electrodes and thin film polymer solid electrolytes. This holds out the hope of being able t o manufacture all thin film solid state PEC's without the semiconductor surface corrosion problems associated with liquid electrolyte PEC's. In addition, it allows easy construction of multispectral thin film cells based on more than one semiconductor material i n optical and electrical series (2). Our present study has focussed on surface modification techniques for improving the rates of charge transfer between semiconductor electrodes and redox ion couples i n polymer electrolytes (3). Specifically, we have shown that surface modifications of n-Si electrodes with thin films of polypyrrole can dramatically reduce the large activation energy barrier against efficient charge transfer between bare semiconductor electrodes and solid polymer electrolytes.