Enhanced Performance of Flexible Organic Photovoltaics Based on MoS₂ Micro-Nano Array

In this work, we investigated the influence of MoS₂ functioning as an electron transport layer (ETL) on the inverted flexible organic photovoltaics (FOPVs). Three ETLs, including MoS₂, lithium quinolate (Liq), and a MoS₂/Liq bilayer, were evaporated onto ITO-integrated polyethylene terephthalate substrates (PET-ITO), and the properties of transmittance, water contact angle, and reflectivity of the films were analyzed. The results revealed that MoS₂ was helpful to improve the lipophilicity of the surface of the ETL, which was conducive to the deposition of the active layer. In addition, the reflectivity of MoS₂ to the light ranging from 400 to 600 nm was the largest among the pristine PET-ITO substrate and the PET-ITO coated with three ETLs, which promoted the efficient use of the light. The efficiency of the FOPV with MoS₂/Liq ETL was 73% higher than that of the pristine device. This was attributed to the nearly two-fold amplification of the MoS₂ array to the light field, which promoted the FOPV to absorb more light. Moreover, the efficiency of the FOPV with MoS₂ was maintained under different illumination angles and bending angles. The results demonstrate the promising applications of MoS₂ in the fabrication of FOPVs.