Enriched semiconducting single wall nanotubes as back contact for CdTe solar cell

For CdS/CdTe solar cells with conventional Cu doped CdTe at the back contact, the diffusion of copper into CdS window layer is detrimental to the solar cell performance. In order to obviate this problem, single wall carbon nanotube thin films with enriched semiconducting ratio (95% S-SWNT) are applied to the CdS/CdTe device and their suitability as back contact materials are studied. We achieve solar cells with power conversion efficiency (PCE) of ~9.71% device using SWNT/Au back contact. Furthermore, the device with SWNT/Au electrode shows higher thermal stability when compared to devices with Cu/Au electrodes.

I. Introduction

The highest power conversion efficiency (PCE) of CdTe solar panel and lab device fabricated by First Solar has achieved 18.6% and 21.5% respectively in 2015 [1]. While these records set a milestone for thin film solar cells, the theoretical maximum 32% efficiency of CdTe solar cell indicates that the full potential of CdTe solar energy material has yet been explored, and that it is still possible to further bring down the cost of solar electricity.