Enhanced Performance of Flexible Organic Photovoltaics Based on MoS(2) Micro-Nano Array

In this work, we investigated the influence of MoS(2) functioning as an electron transport layer (ETL) on the inverted flexible organic photovoltaics (FOPVs). Three ETLs, including MoS(2), lithium quinolate (Liq), and a MoS(2)/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 MoS(2) 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 MoS(2) 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 MoS(2)/Liq ETL was 73% higher than that of the pristine device. This was attributed to the nearly two-fold amplification of the MoS(2) array to the light field, which promoted the FOPV to absorb more light. Moreover, the efficiency of the FOPV with MoS(2) was maintained under different illumination angles and bending angles. The results demonstrate the promising applications of MoS(2) in the fabrication of FOPVs.