DFT and TD-DFT Calculations of Orbital Energies and Photovoltaic Properties of Small Molecule Donor and Acceptor Materials Used in Organic Solar Cells

DPP-bridged narrow band gap oligomer-like donor materials: significant effect of molecular structure regulation on photovoltaic performance

“…23 According to DFT and TD-DFT, using B3LYP/6-31G (d) as the basis set, the electronic density distribution, frontier molecular orbital (FMO) energy level, absorption spectrum, density of state (DOS), and electrostatic potential (ESP) can be calculated and simulated theoretically. 24 It should be noted that in order to simplify the calculation process, the long alkyl chains R 1 and R 2 are replaced by methyl groups. The optimized geometries with torsion angles, calculated molecular orbital energy levels, and predicted UV-Vis absorption spectra are shown in Fig.…”

Density Functional Theory Simulation of Dithienothiophen[3,2-b]-pyrrolobenzothiadiazole-Based Organic Solar Cells

“…Following our recent simulation work [28,29], the molecular structures are initially designed using Avogadro software (version 1.98.1). The seven distinct molecules, namely (a) BTP-(4F) IC, (b) BTP-(4Cl) IC, (c) BTP-CPTCN, (d) BTP-IC, (e) BTP-IN, (f) BTP-Malononitrile, and (g) BTP-Rhodanine, are subjected to a comprehensive simulation process to attain the optimized ground state equilibrium structures, as shown in Figure 2.…”

“…The self-consistent field (SCF) convergence criteria and print options are carefully chosen to balance the accuracy and computational efficiency. Using the optimized equilibrium ground state structures (Figure 2), we compute the equilibrium energies, single-point energies, and E HOMO and E LUMO , which are used for calculating the photovoltaic and quantum chemical parameters, as described in our earlier work [28,29]. Finally, TD-DFT calculations implemented in Orca (version 5.1) [30], are performed to calculate the electronic transitions in each molecule.…”

“…The B3LYP functional is again employed with the def2-SVP and def2/J basis sets, utilizing the RIJCOSX approximation and a tight SCF convergence. The TD-DFT calculations includes calculating 30 excited states, the (e) (f) (g) Using the calculated energies E HOMO and E LUMO of each of the optimized structures, the bandgap (E g ), ionization potential (IP), electron affinity (EA), chemical potential (µ), electronegativity (χ), softness (S) and hardness (η) are obtained as follows [28,29,33]:…”

“…Following the procedures published in our earlier work [28,29] and using self-consistent field (SCF) Density Functional Theory (DFT) through the ORCA software (version 5.1), the ground state structure and energy are first optimized, and then, using Time-Dependent (TD) DFT through ORCA, the excited state energies and the absorption spectra in the UV-VIS region are calculated for all seven molecules.…”