Rational design of dithieno[2,3-D:2',3'-D']-benzo[1,2-B:4,5-B'] dithiophene based small molecule donor for plausible performance organic solar cell

Abstract

A Series of four end-capped tailored dithieno[2,3-d:2',3'-d']-benzo[1,2-b:4,5-b'] dithiophene (DTBDT) core-based donor chromophores (Z1–Z4) are designed with the purpose to enhance PCE of organic solar cells. The photophysical and optoelectronic properties of Z1–Z4 topologies are investigated through Quantum chemical simulation. Density functional theory (DFT) with time-dependent density functional theory (TD-DFT) analysis has been implemented to investigate the effect of side chain substitution (A2) on several parameters such as the density of states, frontier molecular orbitals, transition density matrix, binding energy (Eb), molecular electrostatic potential analysis, dipole moment (µ), open circuit voltage (VOC) and PCE at low energy state geometries. All the designed molecules (Z1–Z4) are scaled up with reference molecule (ZR1-Cl), which concludes that the end-capped acceptor tailoring approach effectively enhanced the molar absorption (?max) of all these designed molecules. Among all molecules, Z3 has shown better absorption properties with a red shift in absorption having ?max at 750 nm in CHCl3 solvent and narrow band gap (1.97 eV) with least excitation energy (Eopt) of 1.65 eV. Z3 also exhibits low exciton binding energy (Eb = 0.32 eV). Moreover, Z1 has excellent charge mobilities owing to the lowest hole mobility (?h = 0.0078) and electron mobility (?e = 0.0088). Among all Z1 has an elevated value of VOC and PCE accountable for more efficient photovoltaic properties. Thus, the results endorsed these molded molecules as a possible choice for designing highly efficient OSCs. Graphical abstract: [Figure not available: see fulltext.]. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.