Dye-sensitized solar cells using carbon nanotube-based counter electrodes in planar and micro-array patterned configurations

Abstract

Dye-sensitized solar cells (DSSCs) have been substantially researched as a prospective candidate for renewable energy technology, and a variety of materials alternative to corroding and high-cost Pt have been utilized as counter electrodes for these cells. In this article, we report on the fabrication and photovoltaic characteristics of DSSCs with vertically aligned carbon nanotube (CNT)-based DSSC counter electrodes. Our DSSCs utilized three different counter electrodes with CNTs in planar (P-CNT) and micro-array patterned (MA-CNT) configurations and platinum (Pt)-film coated Si as the control sample. The CNTs were grown in planar and micro-array patterned configurations directly on highly doped n-type silicon substrates by a hot-filament chemical vapor deposition process. In combination with an N-719 dye-sensitized titanium dioxide (TiO2) coated onto a fluorine doped tin oxide coated glass substrate as the photoanode and an iodide-based electrolyte, our P-CNT as the counter electrode showed a very high photocurrent density (Jsc) of 26.3 mA/cm2 and a power conversion efficiency (η) of 7.13% when compared to platinum's JSC of 20.6 mA/cm2 and η of 6.29%. The photovoltaic behavior of the micro-array patterned CNTs was also characterized, providing a better understanding of their electrocatalytic performance for the DSSCs. Overall, this work demonstrates the superior and improved photovoltaic performance of the vertically-aligned CNTs as the DSSC counter electrode, which makes them a stronger alternative to platinum counter electrodes.