Abstract
The fluorescent molecules utilizing hybridized local and charge-transfer (HLCT) state as potential organic light-emitting diodes materials attract extensive attention due to their high exciton utilization. In this work, we have performed the density functional theory method on three HLCT-state molecules to investigate their excited-state potential energy surface (PES). The calculated results indicate the T1 and T2 energy gap is quite large, and the T2 is very close to S1 in the energy level. The large gap is beneficial for inhibiting the internal conversion between T1 and T2, and quite closed S1 and T2 energies are favor for activating the T2 → S1 reverse intersystem crossing path. However, considering the singlet excited-state PES by twisting the triphenylamine (TPA) or diphenylamine (PA) group, it can be found that the TPA or PA group almost has no influence on T1 and T2 energy levels. However, the plots of S1 PES display two kinds of results that the S1 emissive state is dominated by charge-transfer (CT) or HLCT state. The CT emission state formation would decrease the S1 energy level, enlarge the S1 and T2 gap, and impair the triplet exciton utilization. Therefore, understanding the relationship between the S1 PES and molecular structures is important for designing high-performance luminescent materials utilizing HLCT state.
Highlights
The fluorescent molecules utilizing hybridized local and charge-transfer (HLCT) state as potential organic light-emitting diodes materials attract extensive attention due to their high exciton utilization
Taking the carbazole-dicyanobenzene molecule 4CzIPN (Fig. 1) and triphenylamine-thiadiazole molecule TPA-NZP (Fig. 1) as theoretical models, Pan et al pointed out different reverse intersystem crossing (RISC) paths (T1 → S1 for 4CzIPN and T 2 → S2 for TPA-NZP) by comparing the singlet exciton utilization formats using density functional theory calculation[24]
Understanding the relationship between the S 1 potential energy surface (PES) and molecular structures is important for designing high-performance luminescent materials utilizing HLCT state
Summary
The fluorescent molecules utilizing hybridized local and charge-transfer (HLCT) state as potential organic light-emitting diodes materials attract extensive attention due to their high exciton utilization. The pure organic materials utilizing hybridized local and charge-transfer (HLCT) state[7,8,9] become potential high-efficiency OLED materials considering the low cost, less toxicity, and high exciton utilization. In 2014, a series of twisting donor–acceptor (D–A) molecules with high exciton utilization efficiencies and full-color-range emissions were reported[16]. Taking the carbazole-dicyanobenzene molecule 4CzIPN (Fig. 1) and triphenylamine-thiadiazole molecule TPA-NZP (Fig. 1) as theoretical models, Pan et al pointed out different reverse intersystem crossing (RISC) paths (T1 → S1 for 4CzIPN and T 2 → S2 for TPA-NZP) by comparing the singlet exciton utilization formats using density functional theory calculation[24]. Demonstrate that the ωB97XD or optimally tuned range-separated functional can provide a better description of HLCT state[25,26]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
