Nikhil Tiwari

The star-shaped π-conjugated triangulene frameworks of benzotrithiophene (BTS) offer promising structural motifs for organic optoelectronic materials. Their rigid C3h symmetry, extended delocalization, and their propensity to undergo efficient intersystem crossing make them attractive for emissive applications. However, their further elaboration and systematic exploration in room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) remain largely unexplored. This project will contribute to filling this gap through the design and synthesis of novel donor-π-acceptor (D-π-A) chromophores by functionalizing the benzotrithiophene (BTS) scaffold with naphthalimide and thionaphthalimide acceptor units, incorporating different linkage topologies to modulate π-conjugation and excited-state properties. Both mono-substituted dyads and trisubstituted tetrads will be developed to systematically probe the influence of substitution patterns and conjugation pathways on excited-state properties. Structural variations will be used to modulate frontier orbital alignment, excited-state splitting, and intersystem crossing efficiency. Comprehensive investigations combining photophysical measurements, electrochemical analysis, and DFT/TD-DFT calculations will establish structure-property correlations, providing insight into how acceptor choice and substitution geometry control ΔEST, spin–orbit coupling, and exciton dynamics. The outcomes are expected to define fundamental design principles for BTS-based D-π-A systems, enabling the development of efficient RTP/TADF emitters for next-generation organic optoelectronic technologies.