Vertically Oriented Carbon Nanostructures and Their Application Potential for Polymer-Based Solar Cells

Abstract

One factor limiting the performance of polymer-based bulk heterojunction solar cells is inefficient charge transport in the disordered donor/acceptor blends. The incorporation of carbon nanotubes (CNTs) into the active layer is considered as a promising concept to improve charge transport toward the electrodes. Whereas disordered ternary blends of polymer, fullerenes and CNTs, were already examined in the past, there is much less work on ordered vertically oriented arrays of nanotubes for solar cell applications. We focused on the fabrication of corresponding arrays with spatial dimensions that are suitable for application in polymer-based solar cells. We demonstrate in this contribution that CNTs can be grown on ITO covered glass at temperatures below 600 °C by static pressure chemical vapor deposition (CVD). Using short growth times, we were able to obtain CNT arrays with a rather uniform length limited to about 200 nm. With a plasma-enhanced CVD process, we were also able to produce wall-like carbon na...