Large-area and high-efficiency carbon nanotube/silicon heterojunction solar cells enabled by self-similar fiber electrodes and solid-state gel electrolytes

Abstract

Carbon nanotube/silicon (CNT/Si) Van der Waals heterojunction solar cells have attracted increasing attention due to their low-cost, easy-fabrication process and potential use in next generation photovoltaics. Herein, we reported a high-performance and large-area solar cell fabricated using high-quality CNT films, self-similar CNT fibers and solid-state gel electrolytes. The power conversion efficiency of the fabricated device reached 13.1 % in an active area of 1 cm2, which is much higher than that of the pristine CNT/Si device (7.19 %). In this system, small-bundled and carbon-welding structure at inter-tube junctions enable the CNT film with excellent conductivity. The CNT fiber electrodes were adopted as front contact grids to further reduce the resistance of the CNT film owing to their high conductivity and self-similar microstructure. The solid-state gel electrolyte functions as a p-type dopant to enhance the conductivity of CNTs and the built-in potential at the heterojunction, meanwhile its antireflection property contributes to a significant improved photocurrent of the solar cells. This simple and effective way provides a facile route for developing high-performance, large-area CNT/Si Van der Waals heterojunction solar cells.