Terminal Acceptor-Substitution Controls Optoelectronic Properties in Triphenylamine Based Donors for Organic Solar Cells: A DFT Approach
Year: 2026
Type: preprint
Abstract: Organic solar cells offer opportunities for lightweight and flexible solar energy conversion, motivating development of molecular systems with tunable optoelectronic properties. In this study, six novel triphenylamine-based small-molecule donors (RD1-RD6) having donor-πacceptor (D-π-A) design, where dimethoxy triphenylamine-donor, thiophene-bridge, and phenyl with 1,3-indandione derivatives-acceptors are investigated to understand how the terminal acceptor regulates their molecular, electronic and excited state properties. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations are employed to understand their structural, optoelectronic and charge-transfer properties. Terminal acceptors via different substitutions systematically modulate frontier orbital energies, with HOMO-LUMO gaps ranging from 1.62 to 2.23 eV, absorption maxima of 396-469 nm, and pronounced intramolecular charge transfer characteristics reaching 69.57%. RD6 exhibited the deepest HOMO (-4.96 eV), highest calculated dipole moment (21.33 D) in methanol, and substantial electron-hole separation, whereas RD3 exhibited the narrowest HOMO-LUMO gap (1.62 eV). All the molecules showed low reorganization energies especially for electrons (0.02 - 0.08 eV), high light-harvesting efficiencies (0.89 - 0.98), and favorable intrinsic charge-transfer characteristics. A Scharber-type model applied to RD6 predicts theoretical PCEs of 18.50% and 19.83% for the binary RD6:Y6-2Cl and ternary RD6:L8-BO:Y6-2Cl configuration. Overall, the results demonstrate that terminal acceptor engineering provides an effective way for tuning electronic and excited-state properties of triphenylamine-based donors.
Source: ChemRxiv
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7222162348