Unveiling the potential of π-conjugated 2TT-R non-fullerene alternatives for multifunctional optoelectronic applications: A first-principles study.

Organic solar cells (OSCs) offer lightweight, flexible, and cost-effective energy solutions. However, fullerene-based systems face limitations in stability, tunability, and absorption, prompting the exploration of non-fullerene alternatives to enhance efficiency and scalability. In this work, five newly designed molecules (2TT-1A to 2TT-5A) were systematically studied using Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) at the B3LYP/6-311G (d, p) level in both gas and solvent (chloroform) phases. Key optoelectronic properties, including HOMO-LUMO gaps, absorption spectra, dipole moments, and excitation energies, were analyzed to evaluate their photovoltaic performance. All compounds demonstrated strong light-harvesting abilities, with a notable redshift in the absorption spectra observed in the solvent phase. Among them, 2TT-5A stood out with the narrowest energy gap (1.35 eV), the longest absorption wavelength (861 nm), the highest dipole moment (12.17 D), and the lowest excitation energy (1.43 eV), indicating efficient charge transfer and exciton dissociation. Open-circuit voltages (Voc) ranging from 0.54 to 1.38 V also suggest good photovoltaic potential. Additionally, the nonlinear optical (NLO) and organic light-emitting diodes (OLED) properties of 2TT-5A were explored, revealing significant hyperpolarizability and a favorable emission profile. These results suggested that 2TT-5A is an exceptional multifunctional candidate, encouraging experimental synthesis and validating this material's stability, potentially accelerating the development of multifunctional organic optoelectronic devices.