Programme

O.30 -- Oral, VCTP-50

Date: Thursday, 7 August 2025

Time: 16:00 - 16:25

Assessing the impact of ligand substitution on the optoelectronic properties and electron transport behavior of oligophenylene ethynylene

Nguyen Thi Bao Trang (1,2), Huynh Thi My Hanh (3), Nguyen Vo Anh Duy (1), Nguyen Hoang Hieu (1,2), Pham Vu Nhat (2), Minh Triet Dang (2)

(1) FPT University, Can Tho campus, 600 Nguyen Van Cu Street, Can Tho 900000, Vietnam (2) Can Tho University, 3-2 Road, Can Tho 900000, Vietnam (3) Nguyen Trai High School, Ben Tre 86000, Vietnam

We present a comprehensive theoretical investigation into the effects of ligand substitution on the optoelectronic and electron transport properties of oligophenylene ethynylene (OPE) molecular wires, employing density functional theory in conjunction with the non-equilibrium Green’s function formalism. We show that functionalization of OPE with electron-withdrawing groups, most notably –NO2, leads to a pronounced narrowing of the HOMO–LUMO energy gap and a substantial redshift in the optical absorption spectrum, indicating enhanced electron affinity and improved photophysical response. The electron transport characteristics are significantly modulated by ligand type; OPE derivatives containing –NO2 and –CN exhibit superior electron conductivity at low bias voltages, while the –NH2-functionalized OPE demonstrates ambipolar transport behavior with balanced charge carrier mobility. The computed triplet excitation energies (ET1) suggest that all substituted OPEs are suitable candidates for red-emitting optoelectronic applications, with derivatives bearing –NH2, –Cl, and –CN ligands exhibiting enhanced photoluminescence efficiency due to favorable charge recombination profiles. These findings establish a direct correlation between ligand identity and electronic function, offering design principles for tailoring the performance of π-conjugated molecular semiconductors in nanoelectronic and optoelectronic applications.

Presenter: Nguyen Thi Bao Trang