A leap forward in the optimization of organic solar cells: DFT-based insights into the design of NDI-based donor-acceptor-donor structures

This study presents the design and analysis of four novel small molecules with a donor-acceptor-donor (D-A-D) architecture, incorporating naphthalene diimide (NDI) as the central electron acceptor core, flanked by different electron-donating units: 4H-dithieno [3,2-b:2 ',3 '-d]pyrrole (DTP), isomeric 7H-dithieno-[2,3-b:3 ',2 '-d]pyrrole (iso-DTP), phenothiazine, and diphenylamine. The optical, electronic, and photovoltaic properties of these structures were evaluated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) at the WB97XD/6-311+G (d,p) theoretical level. The selected calculation method showed excellent agreement with experimental data for the synthesized NDI-C3 molecule, validating the computational approach. Our findings highlight the significant role of electron-donating groups in enhancing photovoltaic properties, including increased open-circuit voltage, improved charge density distribution, and enhanced parameters such as fill factor, radiation lifetime, and light harvesting efficiency compared to the NDI-C3 structure. These promising results underscore the potential of our designed molecules for efficient application in organic solar cells and their significant contribution to the advancement of photovoltaic technology.