High efficiency flexible PEDOT:PSS/silicon hybrid heterojunction solar cells by employing simple chemical approaches

Abstract

In the development of efficient and cost-effective hybrid heterojunction solar cells (HHSCs), thin-flexible solar cells based on conjugated polymer poly(3,4-ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS) and flexible silicon (Si) wafers are extremely promising. Here, high efficiency thin-flexible (≤40 microns) HHSCs are reported by employing simple chemical approaches of surface conditioning and solar cell processing. Starting from the as-cut low-cost solar-grade Si wafers (∼200 μm), preparation of thin flexible Si wafers and their controlled surface engineering for enhanced light absorption, maintaining excellent mechanical flexibility, is achieved via aqueous alkali treatment under different conditions. The simple one-step alkali texturing process is capable of enhancing the light trapping properties of the thin-flexible Si wafer significantly in the broad spectral range of 400–1100 nm, also complemented by FDTD analysis. Power conversion efficiency (PCE) as high as 10.42% has been demonstrated for the flexible HHSCs, the highest for flexible HHSCs (≤40 microns) in the basic device architecture using the low cost solar grade Si wafers and simple processing steps. The study is supported by the results of surface morphology, light absorption, passivation, and interface properties along with device performance parameters extracted from the analysis of J–V characteristics, quantum efficiency, and impedance spectroscopy measurements. The study may lead to development of next-generation efficient thin-flexible HHSCs on economical Si wafers as the usage of Si is reduced by four-fold.