Acceptor engineering of D–A–D organic photovoltaic molecules for enhanced optoelectronic and photovoltaic performance: a DFT and TD-DFT investigation

Abstract

This study reports theoretical investigation of series of D-A-D organic photovoltaic (OPVs) molecules, which are designed by acceptor engineering of reference R(TT-TTPA) molecule to improve optoelectronic and photovoltaic properties. Acceptor moieties were systematically modified to improve intramolecular charge transfer, light absorption and charge-transport properties, leading to systematic development of four new derivatives, TTPA01-TTPA04. The calculations carried out with Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) methods at CAM-B3LYP/6-31G(d,p) level in chloroform as a solvent. Frontier molecular orbitals, density of states, global reactivity descriptors, transition density matrix (TDM), dipole moment, open-circuit voltage (V_OC), fill factor, and exciton binding energy calculated. Designed molecules displayed lower energy band gaps than reference R(TT-TTPA) molecule, which means that they have better charge transfer ability and better photovoltaic potential. TTPA02 had lowest bandgap (1.5263 eV) highest electrophilicity and strongest charge-transfer ability among all derivatives, while TTPA04 had most significant redshift in absorption and lowest excitation energy. The highest V_OC and fill factor of TTPA03 indicated better device efficiency. Overall, acceptor modification significantly improved electronic and optical assets of designed systems, highlighting their strong potential promising candidates for next-generation high-efficiency organic solar cells (OSCs) applications.

Graphical abstract