Research Information System
6th Organic Chemistry Congress with International Participatio, Eskişehir, Turkey, 10 - 13 September 2025, pp.84, (Summary Text)
Organic photovoltaics (OPVs) have emerged as promising materials for sustainable energy technologies due to their flexibility,
lightweight structure, and low production costs [1-3]. With the increasing interest in organic semiconductors, both
theoretical and experimental studies have intensified to improve OPV performance [4, 5]. In this context, the electronic
properties of active-layer molecules play a crucial role in device efficiency.
This study presents the design of donor–acceptor–donor (D–A–D) type small molecules based on a [1,2,5]thiadiazolo[3,4-g]
quinoxaline (TQ) acceptor core and a 6H-pyrrolo[3,4-b]pyrazine donor unit. Terminal positions were modified with various
acceptor groups including benzotriazole, isoindole, phthalimide, and benzimidazole. Additionally, cyano (–CN) substitutions
were introduced to assess their influence on electronic structure.
Theoretical calculations were conducted using density functional theory (DFT) and Time-Dependent DFT (TD-DFT) at the
6-31G and 6-31G+** basis set levels. Key optoelectronic parameters such as HOMO–LUMO energy levels, optical band
gaps, open-circuit voltage (Voc), light harvesting efficiency (LHE), fill factor (FF), and power conversion efficiency (PCE)
were evaluated. According to Scharber model predictions, molecules with benzotriazole and isoindole units, especially those
with CN groups, showed superior performance with low band gaps (1.3–1.5 eV) and high open-circuit voltages (>1 V).
Structural analysis revealed near-planar geometries, promoting π-conjugation and enhancing charge transport.
These results highlight the critical influence of terminal acceptor group selection and cyano substitution on OPV efficiency.
The designed TQ-based small molecules are promising candidates for high-performance and stable OPV applications.