Stabilization of <i>n</i>-type silicon photoanodes against photoanodic decomposition with thin films of polyacetylene

Photoelectrochemical cells based on polyacetylene coated n-Si photoanodes, n-Si/(CH)x, in 11 M LiCl solutions containing I−3/I− have been investigated. The n-Si/(CH)x photoanodes show a substantial improvement in durability compared to naked n-Si photoanodes. The efficiency of these photoelectrochemical cells appears to be limited by a low observed quantum yield for electron flow due to absorption of light by the electrolyte solution and by the (CH)x film. Overall efficiency of 1.9% of the conversion of 632.8-nm light (21 mW/cm2) can be sustained for &amp;gt;20 h without significant decline in efficiency. The n-Si/(CH)x photoanode immersed in I−3/I− media behaves as a Schottky barrier or metal-insulator-semiconductor structure where the (CH)x can be viewed as having a variable work function depending on the extent of doping. decomposition with thin films of polyacetylene