Bifacial CdS/CdTe thin-film solar cells with copper nanowires as a transparent back contact.

Abstract

A bifacial CdS/CdTe thin-film solar cell with a superstrate configuration was demonstrated by using copper nanowire (CuNW)/indium tin oxide (ITO) back contacts as a transparent and conductive electrode (TCE). CdS and CdTe were deposited by chemical bath deposition and close-spaced sublimation techniques, respectively. The CuNWs acted both as an acceptor dopant and TCE for the p-CdTe, improving the total cell efficiency compared to a copper-free back contact. CuNW/ITO back contacts with high optical transmittance (72.3% at 550 nm) and low sheet resistance (47.1 Ω/sq.) were obtained. The average cell efficiency of the bifacial CdS/CdTe thin-film cells with the optimized CuNW/ITO back contact was 10.0% (front-side illumination) and 0.55% (rear-side illumination). The quantum efficiencies under front-side and rear-side illumination were studied. The prepared bifacial cell can facilitate full usage of incoming sunlight (direct or diffused), enhancing the output power under cloudy conditions.