Modulated structure to maximize the open-circuit voltage with moderate band-gap of small molecule organic solar cells-DFT approach

Abstract

Pre-synthesis of virtual screening of newly designed four small molecules was approached using Density Functional Theory method. ‘Medium donor-vinylene-strong acceptor’ concept was used to design four small molecules. Malononitrile is flanked on the donor moiety of benzo[1,2-b:6,5-b, dithiophene-4,5-dione(BDTD) which were blended with vinyl linked benzothiadiazole (BTD) acceptor moiety studied with strong electron withdrawing groups (EWG) such as F, CN, and NO2onto the benzothiadiazole unit. DFT and TD-DFT (Time Dependent Density Functional Theory) results of studied small molecules with 1.79eV- 2.06eV band-gap with simulated high open-circuit voltage of 1.38V - 1.49V and predicted power conversion efficiency of designed small molecules is shown using schraber diagram. Detailed investigation of this study is described in this manuscript.