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The popularly used global, meta‐GGA, and range‐separated hybrid DFT functionals are examined to compare the predictive qualities of singlet excited state (S1) properties in HLCT materials. Among these hybrid DFT functionals, it is clarified that both M06 and LC‐ω*HPBE functionals show quantitatively and qualitatively excellent predictions of absorption energies, compared to experiments. However, a discrepant behavior in predicting the emission energy is found that LC‐ω*HPBE functional obviously predicts more accurate emission energy than M06 functional. Also, the calculated τs values by means of M06 and LC‐ω∗HPBE functionals show that LC‐ω∗HPBE functional gives quantitatively and qualitatively superior prediction. Consequently, it is suggested that LC‐ω*HPBE functional should be used to conduct the essential photo‐physical properties of HLCT materials in S1 state. [ABSTRACT FROM AUTHOR]

Multimaterial emission layer (EML) with host and dopant is known for its advantages in efficiency and lifetime for organic light‐emitting diodes (OLEDs). However, as the compositions and the mixing ratio in the EML diversify, complex device physics and photophysics and complicated fabrication processes become challenging issues. Herein, a new concept to integrate exciton donor (host) and acceptor (dopant) into a single emitting molecule is suggested. 9‐(8,9,10,11‐Tetradeuterospiro[benzo[de]anthracene‐7,9′‐fluoren]‐2'‐yl)‐9H‐carbazole (SBAF‐Cz) and 8,9,10,11‐tetradeutero‐N‐(9,9‐dimethyl‐9H‐fluoren‐2‐yl)‐N‐phenylspiro[benzo[de]anthracene‐7,9′‐fluoren]‐3‐amine (FPA‐SBAF) are used as host and dopant, respectively. By integrating two units, 8,9,10,11‐tetradeutero‐2′‐(9H‐carbazol‐9‐yl)‐N‐(9,9‐dimethyl‐9H‐fluoren‐2‐yl)‐N‐phenylspiro[benzo[de]anthracene‐7,9′‐fluoren]‐3‐amine (FPA‐SBAF‐Cz) is synthesized, and photophysical and electrical properties are characterized. Density functional theory and experimental results consistently reveal that SBAF‐Cz and FPA‐SBAF are photophysically and electrically independent. The electrical properties of FPA‐SBAF‐Cz behave independently, while the photophysical properties are the sum of those of SBAF‐Cz and FPA‐SBAF, which is attributed to the zero radius of intramolecular energy transfer (ZRIET) between donor and acceptor in FPA‐SBAF‐Cz. The single‐component blue OLED with FPA‐SBAF‐Cz exhibits a maximum external quantum efficiency of 4.18%, which is higher than those of OLEDs with SBAF‐CZ:FPA‐SBAF multicomponent EMLs. Surprisingly, the device lifetime to 50% decrease from initial luminance is 114 h in FPA‐SBAF‐Cz OLED, which is 2.2 times longer than that of SBAF‐Cz:FPA‐SBAF OLEDs. [ABSTRACT FROM AUTHOR]

A series of M-quinolate complexes were theoretically investigated to understand the effect of metal ions on electronic and charge transport properties by employing density functional theory simulation. It was found that both electronic and carrier transport properties in M-quinolate materials significantly depend on singly oxidized metal ions. In particular, Csq apparently showed an excellent advantage over other M-quinolate materials (M = Li, Na, K, Rb, Cs, Cu, Ag, and Au) in terms of electron mobility and injection. In addition, the dimerization and vertical detachment energies of all M-quinolate materials were compared to understand self-aggregation effect on carrier transport. As a result, it is expected that Csq is not only likely to be present in dimer form, but also reduce the density of electron traps in electron transporting materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Density functional theory calculations were performed to understand the charge transport property of Liq-mixed ETL matrix. • The stabilization energy calculations revealed that forming the ETL-Liq complex is favorable. • The co-deposition of Liq in ETL matrix generally weakens the charge transport property via forming an ETL-Liq complex. The effect of coordinated structures of electron transporting materials (ETM s) with lithium quinolate (Liq) on charge transport characteristics was theoretically investigated. The reorganization energies of holes (λ h) and electrons (λ e) of ETM - Liq simultaneously increased compared with those of ETMs, indicating that the charge transporting is retarded. Interestingly, λ e of ETM -(Liq) n increased, while λ h decreased. Regarding transfer integrals for holes (t h) and electrons (t e), t h 's of T2T - Liq and BPyTP2 - Liq were significantly reduced with t e of T2T - Liq decreasing tremendously. Consequently, the hopping rates of holes of Liq- complexes were reduced, while that of electrons of BPyTP2 - Liq increased and that of T2T - Liq / TSPO1 - Liq was reduced. [ABSTRACT FROM AUTHOR]

The pursuit of hybridized local and charge transfer (HLCT) excited state-based emitters is a promising strategy to achieve high external quantum efficiency in blue organic light-emitting diodes (OLEDs). Two isomeric dimethyl-dihydroindenocarbazole-anthracene-phenanthroimidazole-based emissive molecules (PhAnsIn and PhAnoIn) were designed and explored based on the HLCT scheme. All molecules possessed the HLCT excited-state characters, according to the photophysical investigation and density functional theory calculations. Consequently, PhAnsIn and PhAnoIn showed good blue emission with peaks at 457 and 464 nm and photoluminescence quantum yield of 80.6% and 56.5% in neat films, respectively. The fabricated blue OLEDs with PhAnsIn and PhAnoIn as emitters also realized the corresponding blue emission with electroluminescence peaks at 458 and 457 nm, respectively. The nondoped devices based on PhAnsIn and PhAnoIn exhibited maximum external quantum efficiencies of 8.2% and 8.5% with CIE coordinates of (0.14, 0.12) and (0.14, 0.11), respectively. • Hybridized local and charge transfer excited state based blue fluorescence emitter. • High photoluminescence quantum yield of 80.6% in a neat film. • Non-doped blue fluorescence organic light-emitting diodes with external quantum efficiency of 8.2%. [ABSTRACT FROM AUTHOR]

The insight into understanding the effect of acceptor moieties with phenoxazine (PXD) donor and bridging phenyl (Ph) spacer on structural and electronic properties of excited state was theoretically investigated through density functional theory simulations. Di-phenyltriazine (DPhTRZ), di-phenyl pyrimidine (DPhPyM) , and di-pyridyl pyrimidine (DPyPyM) were chosen as acceptor moieties for thermally activated delayed fluorescence (TADF) emitters. It was found that planar structure between phenyl spacer and DPhTRZ / DPyPyM was dominantly determined by intramolecular H-bonds at inner side of acceptor moiety. Depending on the acceptor moieties, the adiabatic excitation energy in singlet and triplet state is shifted to higher energies in order: DPyPyM (blue) > DPhPyM (greenish-blue) > DPhTRZ (green). In the perspective of spin conversion, the exact spin flip barrier, defined as total energy barrier for triplet-to-singlet transition, is in order of DPhTRZ < DPyPyM < DPhPyM. The calculated spin-orbit coupling matrix element with DPyPyM is relatively larger than that with DPhTRZ and DPhPyM. The calculated reverse intersystem crossing rate for triplet conversion is the largest with DPhTRZ and the smallest with DPhPyM. The comprehensive analyses conclusively suggest that DPyPyM acceptor moiety can be utilized for blue TADF emitters with superb structural rigidity, large spin conversion rate and low spin flip barrier. Image 1023115 • The effect of the acceptor moieties on the structural and photophysical properties of TADF emitters were by DFT simulation. • The planar structure with DPyPyM was dominantly determined by intramolecular H-bonds at inner side of acceptor moiety. • DPyPyM can be used to design highly efficient conventional blue TADF emitter with good rigidity and fast RISC rate. [ABSTRACT FROM AUTHOR]