Molecular designing of four high performance pyrazine-based non-fullerene acceptor materials with naphthalene diimide-based small organic solar cells.

We design four high performance non-fullerene acceptor materials by applying strong electron withdrawing groups at the end of A-D-A-D-A type organic solar cells molecules and compute their different opto-electronic and photovoltaic properties, including absorption spectrum, electron density, solubility strength, charge mobilities for electrons and holes, stability of HOMO/LUMO energy orbitals, excitation energies required for charge transfer mechanisms, and morphology of device with the help of DFT approaches using the principles of quantum mechanics. The newly designed molecules showed strong absorption bands between 420 to 650 nm, low HOMO energy values from -7.24 to -7.28 eV, large % ETC from 35 to 65%, and small excitation energies from 2.28 to 2.47 eV in the organic solvent chloroform; 410 to 620 nm, 31 to 64%, and 2.42 to 2.56 eV, respectively, in gas phase conditions. Solubility strengths of the newly designed molecules were also high, varying from 5.3039 to 18.4749 Debye in the ground and excited states. Power conversion efficiencies of the designed molecules are expected to be high because they show better results than the R molecule. Open circuit voltages of designed molecules range from 3.67 to 3.54 V with respect to the PCBM. Reorganization energies for electron transport vary from 0.0153 to 0.0175 eV and for hole transport from 0.0231 to 0.0254 eV. This computational study proves that the newly designed molecules with non-fullerene acceptors are superior and thus are recommended for the future construction of high performance organic solar cells devices. Graphical Abstract Orbital's energy comparisons of four newly designed non-fullerene acceptor materials with naphthalene diimide-based small organic solar cells.