Quinoxaline based unfused non-fullerene acceptor molecules with PTB7-Th donor polymer for high performance organic solar cell applications

Abstract

Unfused non-fullerene acceptors possess advantages such as simplicity of synthesis, low toxicity, high yield with less manufacturing cost. In the present era, the rapid emergence of new unfused acceptors with high yields and stability is an urgent need. This report has developed four new fullerene-free quinoxaline-based unfused acceptor molecules (QX1 to QX4) for high-performance organic solar cell applications. All designed molecules have a long conjugating backbone which facilitates easy charge transportation between donor and acceptor ends. Different physiochemical, optoelectrical, and photovoltaic properties of designed molecules have been explored through density functional theory (DFT), and time-density functional theory (TD-DFT). A significant reduction in energy bandgap with red-shifting in absorption spectrum was noted for QX1 to QX4. Further, QX1 to QX4 exhibited good values of open-circuit voltage with low excitation and binding energies. Transition density matrix (TDM) analysis was also performed to explore the charge transfer behavior in the designed molecule. In addition, QX1 to QX4 expressed high mobility of electrons and holes with high molecular orbitals contributions. Outcomes of different geometric parameters suggested that QX1 to QX4 are excellent acceptor molecules (when blended with PTB7-Th polymer) for the active layer of organic solar cells.