Application of Polymer Interlayers in Silicon–Carbon Nanotube Heterojunction Solar Cells

We explore the use of polymers as a conducting interlayer within silicon–carbon nanotube heterojunction photovoltaics. Three types of devices have been fabricated and characterized including silicon–carbon nanotube, silicon–conducting polymer and silicon–conducting polymer–carbon nanotube. The conducting polymers studied were polyaniline, poly(3‐hexylthiophene‐2,5‐diyl) and poly(3,4‐ethylenedioxythiophene): poly(styrene sulfonate). A thin conducting polymer interlayer significantly improves photovoltaic performance by creating a better depletion layer within the underlying silicon. With the addition of a top antireflection layer, a photovoltaic device, silicon‐poly(3,4‐ethylenedioxythiophene): poly(styrene sulfonate)–carbon nanotube–poly(styrene) has been fabricated with a photovoltaic conversion efficiency of 8.7 %.