Asymmetric anthracene hosts decorated with naphthobenzofurocarbazole for highly efficient deep-blue organic light-emitting diodes and low-efficiency roll-off

Jeong, Yeong-Ho; Hwang, Kyo Min; Lee, Jae Hee; Kwon, Min Jeong; Kim, T.; Hong, Wu

doi:10.1039/d3tc01681a

Cited by 6 publications

(3 citation statements)

References 44 publications

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“…These TT pairs are weakly exchange-coupled, allowing the ratio of TT pairs to be varied by an external magnetic field. Among them, only the singlet-featured 1 (TT) can transition to the singlet state. − In Figure c, the MEL of Device A1 exhibits a typical TTF MEL fingerprint, sharply increasing at low magnetic fields (<50 mT) and decreasing at high magnetic fields (>50 mT), as only MADN is involved in the emission process. , However, as shown in Figure d,e, the MEL of Device B1 and Device C1 exhibits a different pattern with a sharp increase up to low magnetic fields (∼50 mT) and a slight rise up to high magnetic fields, indicating the presence of an hRISC channel in the MEL fingerprint. − In addition, the MEL intensity decreases with increasing voltage in the high magnetic field, which represents another MEL characteristic of TTF due to its electric-field-dependent process, ultimately confirming that the EEL device involves both the hRISC and TTF processes simultaneously. Comparably, Device B1 with PAC as the EEL exhibits a relatively less decrease in MEL in the high magnetic field region, which might be attributed to the higher contribution to EL by the hRISC channel in PAC.…”

Section: Resultsmentioning

confidence: 95%

Quantitative Analysis of Exciton Dynamics: Investigating the Role of the Efficiency-Enhancement Layer for Blue Fluorescent Organic Light-Emitting Diodes

Park,

Kim,

Kim

2024

ACS Appl. Electron. Mater.

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One effective approach to overcoming the efficiency limits of triplet−triplet fusion (TTF)-based blue organic lightemitting diodes is to utilize the efficiency enhancement layer (EEL), which can increase efficiency through simple modifications in the device structure. However, the physical mechanism of the EEL, particularly exciton dynamics, has not been thoroughly investigated. In this study, the exciton utilization efficiency (EUE) was calculated by considering the host and EEL as individual emission components to analyze the exciton dynamics of the EEL. The materials that exhibit high-lying reverse intersystem crossing (hRISC) characteristics 2-(4-(10-(3-(9H-carbazol-9-yl)phenyl)anthracen-9-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (PAC) and 5-(4-(10-phenylanthracen-9-yl)phenyl)-5H-benzofuro[3,2-c]carbazole (ATDBF) were used as an EEL.The maximum external quantum efficiency (EQE max ) of the device without utilizing the EEL was measured at 3.0%. However, when PAC and ATDBF were utilized as the EEL in the device, the EQE max significantly increased to 4.4 and 4.5%, respectively, resulting in an efficiency improvement of approximately 47−50% compared to when the EEL was not used. To ascertain whether the efficiency enhancement is induced through the hRISC process of the EEL, transient electroluminescence and magnetoelectroluminescence measurements were carried out. The results indicated that the triplets harvested into radiative singlets in the EEL device occurred through the TTF and hRISC processes. Finally, numerical simulations were carried out to evaluate the efficiency contributions from various mechanisms in the nondoped device, including TTF induced from the host (η TTF.H ), TTF induced from the EEL (η TTF.E ), and hRISC induced from the EEL (η hRISC.E ) in addition to 25% of EUE from singles via hole−electron recombination. The calculated η TTF.H , η TTF.E , and η hRISC.E were 3.8, 0.6, and 4.7% for the PAC-based device and 5.5, 0.9, and 12.3% for the ATDBF-based device, respectively. Consequently, while the device using the host alone exhibited an EUE of 31.8%, the incorporation of PAC and ATDBF elevated the EUE to 34.1 and 43.7%, respectively, highlighting significantly enhanced EUE.

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Section: Resultsmentioning

confidence: 95%

Quantitative Analysis of Exciton Dynamics: Investigating the Role of the Efficiency-Enhancement Layer for Blue Fluorescent Organic Light-Emitting Diodes

Park,

Kim,

Kim

2024

ACS Appl. Electron. Mater.

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“…Here, TPA with electron-donating ability and TPE with AIE characteristics were substituted to maintain deep-blue emission with an asymmetric structure. In the case of compounds with asymmetric structures, intermolecular packing is effectively prevented in the film state, resulting in amorphous films and improved device stability [32][33][34]. The optical and electrical properties of synthesized blue chrysene derivatives were compared and analyzed.…”

Section: Molecular Design Synthesis and Characterization Of Organic B...mentioning

confidence: 99%

Improving the Electroluminescence Properties of New Chrysene Derivatives with High Color Purity for Deep-Blue OLEDs

Park,

Lee,

Lee

et al. 2024

Materials

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Two blue-emitting materials, 4-(12-([1,1′:3′,1″-terphenyl]-5′-yl)chrysen-6-yl)-N,N-diphenylaniline (TPA-C-TP) and 6-([1,1′:3′,1″-terphenyl]-5′-yl)-12-(4-(1,2,2-triphenylvinyl)phenyl)chrysene (TPE-C-TP), were prepared with the composition of a chrysene core moiety and terphenyl (TP), triphenyl amine (TPA), and tetraphenylethylene (TPE) moieties as side groups. The maximum photoluminescence (PL) emission wavelengths of TPA-C-TP and TPE-C-TP were 435 and 369 nm in the solution state and 444 and 471 nm in the film state. TPA-C-TP effectively prevented intermolecular packing through the introduction of TPA, a bulky aromatic amine group, and it showed an excellent photoluminescence quantum yield (PLQY) of 86% in the film state. TPE-C-TP exhibited aggregation-induced emission; the PLQY increased dramatically from 0.1% to 78% from the solution state to the film state. The two synthesized materials had excellent thermal stability, with a high decomposition temperature exceeding 460 °C. The two compounds were used as emitting layers in a non-doped device. The TPA-C-TP device achieved excellent electroluminescence (EL) performance, with Commission Internationale de L′Eclairage co-ordinates of (0.15, 0.07) and an external quantum efficiency of 4.13%, corresponding to an EL peak wavelength of 439 nm.

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“…22 Benefiting from this unique advantage, hot exciton emitters are easier to design and can more easily realize deep-blue light than TADF emitters. 23 Previous studies have revealed that the T 2 state of anthracene is energetically close to its S 1 state, with a considerable T 2 –T 1 energy gap of 1.3 eV. 24 This distinctive arrangement of energy levels renders anthracene an excellent candidate for building a high-performing emitter of hot excitons.…”

Section: Introductionmentioning

confidence: 99%

Oxygen-bridged triarylboron substituted anthracene emitters with high-lying triplet–singlet intersystem crossing for efficient deep-blue OLEDs

Lu,

Hu,

Chen

et al. 2024

J. Mater. Chem. C

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Asymmetric anthracene hosts decorated with naphthobenzofurocarbazole for highly efficient deep-blue organic light-emitting diodes and low-efficiency roll-off

Cited by 6 publications

References 44 publications

Quantitative Analysis of Exciton Dynamics: Investigating the Role of the Efficiency-Enhancement Layer for Blue Fluorescent Organic Light-Emitting Diodes

Quantitative Analysis of Exciton Dynamics: Investigating the Role of the Efficiency-Enhancement Layer for Blue Fluorescent Organic Light-Emitting Diodes

Improving the Electroluminescence Properties of New Chrysene Derivatives with High Color Purity for Deep-Blue OLEDs

Oxygen-bridged triarylboron substituted anthracene emitters with high-lying triplet–singlet intersystem crossing for efficient deep-blue OLEDs

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