Carbonyl (CO)/N-based thermally activated delayed fluorescent materials with high efficiency and fast reverse intersystem crossing rate: a theoretical design and study

Abstract

Thermally activated delayed fluorescence (TADF) materials based on multiple resonance (MR) molecular structures can achieve the advantages such as high fluorescence efficiencies, reduced structural relaxations and narrow emissions. It is...

Designing thermally activated delayed fluorescence emitters with through-space charge transfer: a theoretical study

“…The results indicate that all the studied molecules exhibit lower reorganization energies between the S 1 and T 1 states, effectively enhancing K RISC and reducing efficiency roll-off. 44,76 Furthermore, an analysis of the reorganization energies and two key vibrational modes between the S 0 –S 1 and S 1 –T 1 states reveals that larger reorganization energies between S 0 and S 1 are distributed in the low-frequency region (<500 cm −1 ) and the high-frequency region (>1000 cm −1 ). On the other hand, larger reorganization energies between S 1 and T 1 are distributed in the low-frequency region (<500 cm −1 ).…”

“…43 Previous studies have employed first-principles methods to analyze the influence of geometric structures and excited-state properties on the photophysical performance of TADF molecules. 44–49 Additionally, multiscale quantum mechanics and molecular mechanics approaches have been utilized to investigate molecular aggregation, film environments, and their impact on photophysical properties. 50–52…”

Enhancing Reverse Intersystem Crossing in Triptycene-TADF Emitters: Theoretical Insights into Reorganization Energy and Heavy Atom Effects

“…The calculated RMSD values between S 1 and T 1 states of all newly designed TADF molecules are relatively small, suggesting reduced reorganization energies. 28 We calculated the reorganization energies and Huang−Rhys (HR) factors between S 1 and T 1 for these TADF molecules in thin film environments. As illustrated in Figure 4 and Figures S6−8, we analyzed the reorganization energies and two key vibration modes between the S 1 and T 1 states.…”

“…These reduced reorganization energies are beneficial for the increase of RISC rates of OTCO−DMAC, STCO−DMAC, and SeTCO−DMAC. 28,58 We further calculated the photophysical properties of TADF molecules in thin film environments using the MOMAP software. The prompt fluorescence efficiency (Φ PF ), the delayed fluorescence efficiency (Φ DF ), and the overall TADF quantum efficiency (Φ) were calculated based on eqs S3−S7.…”

“…Theoretical investigations into the dependency of TADF molecules’ luminescent performance on their geometrical and electric structures, as well as assembly environments, are pivotal for fostering innovation and expanding applications in OLED technology. ,, Key geometrical structures and excited state properties of TADF molecules can be evaluated based on the first-principles methods, such as density functional theory (DFT). − Furthermore, the dependency of luminescence performance of TADF molecules on the Δ E ST , reorganization energy, and spin–orbit coupling (SOC) constants can be quantified using the Marcus–Levich theory. − To investigate the luminescence mechanism of TADF molecules in different environments (e.g., gas, solution, crystal, amorphous, and doped film states), ,,, the combined quantum mechanics/molecular mechanics (QM/MM) method has been employed.…”