Structural, optical and photovoltaic properties of unfused Non-Fullerene acceptors for efficient solution processable organic solar cell (Estimated PCE greater than 12.4%): A DFT approach

Abstract

For the maximum photovoltaic outputs, molecular modelling was incurred in reported molecules BDCl2F and TClC2F - having PCE value up to 12.4% - to make six novel unfused non-fullerene acceptors. A deep theoretical consideration under the umbrella of TD-DFT and DFT - using method MPW1PW91 with basis set 6-31G (d,p) - was used to look into molecular geometries and molecular electrostatic potential (MEP), optical (the excitation energy and molar absorption coefficient) and photovoltaic parameters [frontier molecular orbitals (FMOs), the density of states (DOS), light-harvesting efficiency (LHE), transition density matrix (TDM), binding energy, reorganization energy, charge transfer properties (open circuit voltage) and fill factor (FF)]. In this work, the modelled molecules have depicted extraordinary structural, optical and photovoltaic characteristics which validate the successful modelling to advance the polymer solar cell (PSC) technology. Out of all explored entities, BDCl2F-AS and TClC2F-AS embarked excellent results (λ max = 859.2 nm and 879.2 nm, µe = 13.48 and 11.79, LHE = 0.9994 and 0.9993, respectively). Similarly, BDCl2F/ PTB7-Th and TClC2F PTB7-Th donor/acceptor interfaces have excellent output values (Voc = 1.21 eV and 1.16 eV, normalized Voc = 46.7633 eV and 44.8309 eV with fill factor (FF) = 0.8982 and 0.8949, respectively). The increase in all analysed parameters comparative to experimentally reported molecules BDCl2F and TClC2F have urged to predict PCE of modelled molecules to be greater than 12.4% which is the PCE values of reported ones. By keeping in mind the entire results, modelled molecules and their interfaces are recommended for PSCs manufacturing usage.