Non-fullerene acceptor IDIC based on indacinodithiophene used as an electron donor for organic solar cells: A computational study

In the present paper, a computational study was performed on a planar non-fullerene acceptor (A-D-A) type based on indacenodithiophene (noted IDIC) which is widely used in the fabrication of organic solar cells. The structural and optoelectronic properties were studied using the Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) approaches with different functionals, such as B3LYP, B3PW91, MPW1PW91. The optoelectronic properties such as HOMO and LUMO energy levels, energy gap, λmax were determined and compared with experimental results reported. Charge transfer properties were further characterized through Frontier Molecular Orbitals (FMOs) and Density of States (DOS). Transition density matrix (TDM) and hole&electron isosurface were used to illustrate the behavior of electronic excitation processes as well as the position of electron holes between the donor and acceptor units. In addition, the IDIC compound was tested as an electron donor with the fullerenes and their derivatives as electron acceptors (PCBM). Both electrochemical and photovoltaic properties were investigated and discussed in detailed. The theoretical results indicated that the B3LYP/6-31G(d,p) and its time-dependent counterpart TD-B3LYP/6-31G(d,p) methods are appropriate to predict the optoelectronic properties. The values of the open-circuit voltage (Voc) of IDIC with used acceptors range from 1.165 to 1.665 V. The results of this study showed the high potential of the IDIC compound for integratation into solar cells as an electron donor material and suggested the usefulness of studied materials as promising candidates for photovoltaics.