Electrically Conductive Polymer Layers on Semiconductor Electrodes

A promising approach to alleviate the photodegration problem at the semiconductor-electrolyte interface of a photoelectrochemically solar cell has emerged. The key component of this strategy is an electrically conductive polymer film that works synergistically with the redox electrolyte and/or a catalyst to stabilize the semiconductor surface from photodegradation and to promote desired reactions at the electrode surface. This paper presents an examination of the viability of this approach and its application to the generation of electrical power and the photoelectrolysis of water. The emphasis is on n-type semiconductors and electrically conductive films of polypyrrole, because this electrode-polymer combination has been the most thoroughly studied. The discussion covers how the physical properties and the chemical environment of the polymer together with the polymer-semiconductor interactions determine the electrode stability and the light-quantum conversion efficiency. The possible application of electrically conductive polymers to control surface states is also discussed.