%0 Journal Article %1 Sivanarayanan_2022 %A Sivanarayanan, Jibin %A Sebastian, Ebin %A Vinod, Kavya %A Würthner, Frank %A Hariharan, Mahesh %D 2022 %I American Chemical Society (ACS) %J J. Phys. Chem. C. %K myown %N 31 %P 13319--13326 %R 10.1021/acs.jpcc.2c03847 %T Ultrafast Intersystem Crossing in Selenium-Annulated Perylene Bisimide %U https://doi.org/10.1021%2Facs.jpcc.2c03847 %V 126 %X An intersystem crossing (ISC), the non-radiative transition between two electronic states with different spin multiplicities, is ubiquitous and imperative in molecular photochemistry. The manifestation of a triplet manifold in π-conjugated chromophoric materials has a crucial role in enhancing the efficiency of photofunctional devices. Herein, we explore the triplet-state population in a series of chalcogen-annulated perylene bisimides (O-PBI, S-PBI, and Se-PBI), where the selenium-annulated PBI (Se-PBI) exhibits a near-quantitative triplet quantum yield ( = 94 ± 1%). Annulation of Se in the PBI core results in a drastic decrease in the fluorescence quantum yield ( = 1.5 ± 0.2%) compared to the bare PBI ( = 97.0 ± 1%), indicating the possibility of an efficient non-radiative decay pathway in the Se-PBI motif. Femtosecond and nanosecond transient absorption measurements unambiguously confirmed the ultrafast triplet population in Se-PBI with an ISC rate constant of = 2.39 × 1010 s–1 and the triplet-state decay to the ground state with a time constant of 3.78 μs. A theoretically calculated spin–orbit coupling constant (VSOC) of 122.4 cm–1 employing the SA-CASSCF/NEVPT2 method has rationalized the excited-state dynamics of Se-PBI. By virtue of the poor SOC between the singlet and triplet states, we observed a partial triplet population in S-PBI, whereas ISC is negligible in O-PBI. We demonstrate an increase in the spin–orbit coupling constant ( ≪ < ) and rate constant of ISC ( ≪ < ) across the series of chalcogen-annulated PBIs (O-PBI, S-PBI, and Se-PBI). The heavier chalcogenide PBI (Se-PBI) thus adds to the array of potential organic photoactive materials for the design of efficient solar energy conversion devices.

@article{Sivanarayanan_2022, abstract = {An intersystem crossing (ISC), the non-radiative transition between two electronic states with different spin multiplicities, is ubiquitous and imperative in molecular photochemistry. The manifestation of a triplet manifold in π-conjugated chromophoric materials has a crucial role in enhancing the efficiency of photofunctional devices. Herein, we explore the triplet-state population in a series of chalcogen-annulated perylene bisimides (O-PBI, S-PBI, and Se-PBI), where the selenium-annulated PBI (Se-PBI) exhibits a near-quantitative triplet quantum yield ( = 94 ± 1%). Annulation of Se in the PBI core results in a drastic decrease in the fluorescence quantum yield ( = 1.5 ± 0.2%) compared to the bare PBI ( = 97.0 ± 1%), indicating the possibility of an efficient non-radiative decay pathway in the Se-PBI motif. Femtosecond and nanosecond transient absorption measurements unambiguously confirmed the ultrafast triplet population in Se-PBI with an ISC rate constant of = 2.39 × 1010 s–1 and the triplet-state decay to the ground state with a time constant of 3.78 μs. A theoretically calculated spin–orbit coupling constant (VSOC) of 122.4 cm–1 employing the SA-CASSCF/NEVPT2 method has rationalized the excited-state dynamics of Se-PBI. By virtue of the poor SOC between the singlet and triplet states, we observed a partial triplet population in S-PBI, whereas ISC is negligible in O-PBI. We demonstrate an increase in the spin–orbit coupling constant ( ≪ < ) and rate constant of ISC ( ≪ < ) across the series of chalcogen-annulated PBIs (O-PBI, S-PBI, and Se-PBI). The heavier chalcogenide PBI (Se-PBI) thus adds to the array of potential organic photoactive materials for the design of efficient solar energy conversion devices.}, added-at = {2022-08-11T14:22:36.000+0200}, author = {Sivanarayanan, Jibin and Sebastian, Ebin and Vinod, Kavya and Würthner, Frank and Hariharan, Mahesh}, biburl = {https://www.bibsonomy.org/bibtex/27c3a49f87182032396c531ac2f32ecc5/wuerthner_group}, doi = {10.1021/acs.jpcc.2c03847}, interhash = {9b3cae746b0fac16317b705d8bbb28e7}, intrahash = {7c3a49f87182032396c531ac2f32ecc5}, journal = {J. Phys. Chem. C.}, keywords = {myown}, month = jul, number = 31, pages = {13319--13326}, publisher = {American Chemical Society (ACS)}, timestamp = {2024-01-25T14:33:45.000+0100}, title = {Ultrafast Intersystem Crossing in Selenium-Annulated Perylene Bisimide}, url = {https://doi.org/10.1021%2Facs.jpcc.2c03847}, volume = 126, year = 2022 }