Tuning the optoelectronic properties of naphthodithiophene (NDT) for designing of A-D-A type photovoltaic materials

For years, scientists are relying on fullerene-free acceptors because of their prominent role in tuning and improving the optoelectronic characteristics and efficiency of photovoltaic cells. To improve the PCE of non-fullerene based OSCs, four new molecules based on A-D-A pattern substituted with different acceptor groups namely NDT1 (malononitrile), NDT2 (methyl-2-cyanoacrylate), NDT3 (2-(5,6-difluoro-3-oxo-2,3-dihydroinden-1-ylidene) malononitrile), and NDT4 (2-(3-methyl-4-oxothiazolidin-2-ylidene) malononitrile) have been designed. All constructed structures have a common central unit, naphtho-dithiophene which is attached to various acceptor groups at the peripheral position. A detailed computational study of optical and electronic properties of designed molecules in comparison to reference molecule NDT shows that NDT3 possesses maximum absorption (473.9 nm) and smallest bandgap (5.26 eV), while NDT1 exhibits the highest Voc (3.17 eV). TDM analysis has been performed which shows efficient charge density transition from core to acceptor groups. Besides that, because of their low reorganization energy values, larger dipole moments, and higher values of Voc, these constructed molecules are considered superior scaffolds for designing of SM-OSCs. Hence, the molecules under scrutiny are likely to be successful acceptors for the fabrication of photovoltaic cells in the future. •Four molecules of naphthodithiophene based compounds have been designed.•The freshly designed acceptor molecules have efficient photovoltaic properties as compared to reference molecules.•Reorganization energy of designed molecules is lower than reference molecule.