Tuning of a A–A–D–A–A-Type Small Molecule with Benzodithiophene as a Central Core with Efficient Photovoltaic Properties for Organic Solar Cells

Abstract

With the aim of upgrading the power conversion efficiency of organic solar cells (OSCs), four novel non-fullerene, A 1 −A 2 −D−A 2 −A 1 -type small molecules were designed that are derivatives of a recently synthesized molecule SBDT-BDD reported for its efficient properties in all-small-molecule OSCs (ASM-OSCs). Optoelectronic properties of the designed molecules were theoretically computed with a selected CAM-B3LYP functional accompanied by the 6-31G(d,p) basis set of density functional theory (DFT), and excited-state calculations were performed through the time-dependent self-consistent field. The parameters of all analyzed molecules describing the charge distribution (frontier molecular orbitals, density of states, molecular electrostatic potential), absorption properties (UV−vis absorption spectra), exciton dynamics (transition density matrix), electron−hole mobilities (reorganization energies), and exciton binding energies were computed and compared. All the designed molecules were found to be superior regarding the aforesaid properties to the reference molecule. Among all molecules, SBDT1 has the smallest band gap (3.88 eV) and the highest absorption maxima with broad absorption in the visible region. SBDT3 has the lowest binding energy (1.51 eV in chloroform solvent) ensuring easier and faster dissociation of excitons to produce free charge-carriers and has the highest open-circuit voltage (2.46 eV) with PC 61 BM as the acceptor. SBDT1 possesses the highest hole mobility because it has the lowest value of λ + (0.0148 eV), and SBDT4 exhibits the highest electron mobility because it has the lowest value of λ − (0.0146 eV). All the designed molecules are good candidates for ASM-OSCs owing to their superior and optimized properties.

Designing dibenzosilole core based, A2–π–A1–π–D–π–A1–π–A2type donor molecules for promising photovoltaic parameters in organic photovoltaic cells

“…A molecule with a high value of dipole moment tends to be highly soluble in a polar organic solvent due to the high degree of charge mobility in it. 63 The increased dipole moments cause the respective molecules to easily self-assemble in a packed and antiparallel orientation, which results in an increased charge transfer rate at the active-layer. 64 A smooth surface of the donor–acceptor interface of the active layer enables the molecule to be readily dissolved, resulting in a more efficient solar device assembly.…”

Synergistic end-capped engineering on non-fused thiophene ring-based acceptors to enhance the photovoltaic properties of organic solar cells

“…The LUMO produced a contraction in the E g and a rise in the wavelength because of the reverse connection between energy and wavelength. 4 …”

“…Solar energy is the only abundant source, since it delivers 3.8 million EJ (EJ ¼ 1018 J) of energy each year which is entirely unrestricted and pollutant-free. 3,4 Solar cells utilize solar energy for the generation of electricity based on the photovoltaic effect; this is illustrated by the fact that when a photon of a particular energy is absorbed, free holes as well as electrons are generated in inorganic solar cells (SCs) or in the joint form in organic SCs as excitons, which create electricity as they go toward the opposite electrodes. [5][6][7] The rst generation of inorganic SCs were presented in 1954, but because of several drawbacks, such as short lifetimes, expensive synthetic approaches, and brittleness, secondgeneration solar cells have replaced them.…”

Engineering of W-shaped benzodithiophenedione-based small molecular acceptors with improved optoelectronic properties for high efficiency organic solar cells

“…Inclusively, the increasing λ max sequence of WR and W1–W7 molecules in gas phase and in the CHCl 3 is WR < W6 < W3 < W5 < W7 < W4 < W2 < W1 and WR < W6 < W5 < W7 < W3 < W4 < W2 < W1, sequentially. Because of the reason that the polar excited state was stabilized with the assistance of a polar solvent, 65 all of the compounds demonstrated a bathochromic shift in chloroform solvent as opposed to when in gas phase. Because of the inverse relationship between energy and wavelength, the reduced E gap of all the molecules caused their wavelength to increase.…”