Theoretical calculations were carried out to investigate the effect of the incorporation of the fluorene bridge on the optoelectrical properties of the emitter as compared to the those of the reference, DiKTa. The geometry in the ground state was first optimized using Density Functional Theory at the PBE0/6-31G(d,p) level. The frontier molecular orbitals are delocalized over the entire p-conjugated system, the HOMO and LUMO show a similar alternating distribution pattern to that of DDiKTa, which is emblematic of MR-TADF compounds. The calculated HOMO and LUMO levels of DDiKTa-F are -5.94 and -2.32 eV, respectively. The HOMO-LUMO gap of 3.62 eV for DDiKTa-F is smaller than that of DDiKTa (DEHOMO-LUMO = 3.70 eV), reflecting an increased conjugation in the former. The locked structure of the molecule contributes to small geometric changes between the S0 and S1 states, as depicted in Figure . It is thus expected that the emission spectrum will be narrow and that there will be a small Stokes shift. The emission spectra of both DiKTa and DDiKTa-F under vacuum were simulated using Frank-Condon analysis based on the S1-S0 transition at the TDA-DFT-PBE0/6-31G(d,p) level (Figure ). The simulated spectrum of DiKTa shows an emission band peaking at lPL of 428 nm and a small FWHM of 14 nm, which closely aligns with the emission in hexane at lPL of 436 nm (FWHM of 21 nm). By contrast, the simulated emission spectrum of DDiKTa-F is red-shifted at lPL of 474 nm and is slightly broader (FWHM of 18 nm). We have previously demonstrated that DFT calculations do not accurately predict the excited-state properties of MR-TADF emitters. Here we employed SCS-ADC(2)/cc-pVDZ calculations to accurately model the excited states of DDiKTa-F. Difference density plots provide information of the changes in the electron density distribution in the exited states compared to the ground state. The difference density plots between S0 and each of the S1 and T1 states, calculated at the ground-state optimized geometry, reveal that these excited states have short-range charge transfer (SRCT) character that is typical of MR-TADF emitters. The calculated energies of the S1 and T1 states are 3.34 and 3.08 eV, respectively, which are lower than those of DiKTa (S1/T1 =3.45/3.18 eV) and DDiKTa (S1/T1 =3.39/3.12 eV), indicating that the emission in this compound should be red-shifted compared to the two reference emitters. The calculated ΔEST for DDiKTa-F is 0.26 eV, which is similar to those of DiKTa (0.26 eV) and DDiKTa (0.27 eV). Similar to that calculated for DDiKTa, DDiKTa-F has doubly degenerate singlet and triplet (ΔES1-2 = 0.06 eV and ΔET1-2 = 0.06 eV) states. The calculated spin-orbit coupling matrix elements (SOCME) between S1 and T1 is 0.37 cm -1 based on the T1-optimized geometry, while the SOCME values between S1 to the four closely lying higher triplet excited states range from 0.07 to 5.93 cm -1 . In particular, the large <S1|ĤSOC|T3> value of 5.93 cm -1 is attributed to an n-p * transition localized on the carbonyl groups (Figure ).