Next generation quantum theory of atoms in molecules for the design of emitters exhibiting thermally activated delayed fluorescence with laser irradiation

The effect of a static electric (E)-field and an unchirped and chirped laser pulse field on the cycl[3.3.3]azine molecule was investigated using next-generation quantum theory of atoms in molecules (NG-QTAIM). Despite the magnitude of the E-field of the laser pulses being an order of magnitude lower than for the static E-field, the variation of the energy gap between the lowest lying singlet (S-1) and triplet (T-1) excited states was orders of magnitude greater for the laser pulse than for the static E-field. Insights into the response of the electronic structure were captured by NG-QTAIM, where differences in the inverted singlet-triplet gap due to the laser pulses were significant larger compared to those induced by the static E-field. The response of the S-1 and T-1 excited states, as determined by NG-QTAIM, switched discontinuously between weak and strong chemical character for the static E-field. In contrast, the response to the laser pulses, determined by NG-QTAIM, is to induce a continuous range of chemical character, indicating the unique ability of the laser pulses to induce polarization effects in the form of mixed bond types. Our analysis demonstrates that NG-QTAIM is a useful tool for understanding the response to laser irradiation of the lowest-lying singlet S-1 and triplet T-1 excited states of emitters exhibiting thermally activated delayed fluorescence. The chirped laser pulse led to more frequent instances of the desired outcome of an inverted singlet-triplet gap than the unchirped pulse, indicating its usefulness as a tool to design more efficient organic light-emitting diode devices.

Automated summary

This study investigated the impact of a static electric field and unchirped and chirped laser pulses on cycl[3.3.3]azine molecules using NG-QTAIM, revealing that the variations in energy gap between the lowest lying singlet and triplet excited states were significantly greater for laser pulses than for static E-field. The response to laser pulses induced a continuous range of chemical character, indicating its unique ability to induce polarization effects in the form of mixed bond types. Furthermore, the chirped laser pulse was found to lead to more frequent instances of inverting the singlet-triplet gap compared to the unchirped pulse, demonstrating its potential for designing more efficient organic light-emitting diode devices.