Deciphering the role of invited guest bridges in non-fullerene acceptor materials for high performance organic solar cells

Fullerene-free acceptor molecules gained great attention of researchers due to their excellent light harvesting capability and low toxicity rate. Herein, six new molecules have been designed by bridging core modifications and analyzed through advanced quantum chemical techniques. Density functional theory and time dependent-DFT have been employed in order to compute optoelectronic, photovoltaic and physiochemical properties of newly designed molecules. Some geometric parameters like alignment of both molecular orbitals, absorption maxima, excitation with binding energies, open circuit voltage, and transition density matrix have been performed in order to examine the structural-property relationship of designed molecules. Efficient bridge atoms of designed molecules cause reduction in energy band gap (1.895–2.375 eV) along with red-shifting in absorption maxima (619–719 nm). Transition density matrix analysis unveils the location of charge density within a molecule along with different transitions. Molecular electrostatic potential analysis suggested that the theoretical planned molecules are symmetrical and have electron rich and poor regions. High open circuit voltage and electron-hole mobility advocated that the designed molecules are good nominees for high performance organic solar cell applications.