Electronic excitation and charge transfer processes are fundamentally interconnected, critically determining the optoelectronic performance of organic semiconductors. The purpose of this study is to systematically examine donor–acceptor (D-A) conjugated polymers at the molecular level, with particular focus on elucidating charge distribution patterns and transition mechanisms to establish advanced design principles for these materials.
A series of bipolar and n-type bisisoindigo (BIID)-based D-A conjugated polymers were investigated from a molecular perspective using density functional theory and time-dependent density functional theory methods. The ground and excited state characteristics of these polymers were analyzed to correlate molecular structures with electronic properties.
This study demonstrates that aza-incorporation and fluoro-substitution have relatively minor effects on the electronic structure, with the latter causing only a slight increase in n-p* transitions. In marked contrast, oxa-incorporation shows substantial impact by significantly expanding electron hole distribution in the vinyl region. This modification effectively establishes a p-electron bridge between receptor units while simultaneously enhancing both charge transition density and electron transfer between structural fragments.
This investigation introduces a methodologically significant approach for the expedited design and rigorous screening of high-performance, air-stable n-type D-A conjugated polymers and organic electronic devices.
