Infrared-transparent polymer solar cells

Abstract

Transparent solar cells are very useful in making transparent electrical power supplies and tandem devices. We report the fabrication of semi-transparent polymer solar cells by replacing conventional metal electrode with a carbon nanotube film. The solar cells can be illuminated at both front and back sides, with power conversion efficiencies (up to 2.5%) comparable to cells using metal electrodes. The solar cells are highly transparent in near-infrared region, with an optical transmittance of nearly 80% in the range of 670 nm to 1.2 μm, and maintain a transmittance of above 60% through 1.2 to 2.5 μm. We further constructed a tandem structure with two subcells operating separately, in which the back cell receives infrared light transmitted through the front cell. Our infrared-transparent solar cells possess multiple functions such as serving as a light filter to drive a CdSe nanobelt photo-sensor with enhanced wavelength selectivity.