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Asymmetrically twisted phenanthrimidazole derivatives as host materials for blue fluorescent, green and red phosphorescent OLEDs
摘要： The electroluminescent properties of asymmetrically twisted phenanthrimidazole derivatives comprised of fluorescent anthracene or pyrene unit namely, 1-(1-(anthracen-10-yl)naphthalen-4-yl)-2-styryl-1H-phenanthro[9,10-d]imidazole (ANSPI), 1-(1-(pyren-1-yl) naphthalene-4-yl)-2-styryl-1H-phenanthro[9,10-d]imidazole (PNSPI), 4-(2-(4-(anthracen-9-yl) styryl)-1H-phenanthro[9,10-d]imidazol-1-yl)naphthalene-1-carbonitrile (ASPINC) and 4-(2-(4-(pyren-1-yl)styryl)-1H-phenanthro[9,10-d] imidazol-1-yl)naphthalene-1-carbonitrile (PSPINC) for blue OLEDs have been analyzed. The asymmetrically twisted conformation interrupt π-conjugation effectively results in deep-blue emission. The pyrene containing PSPINC based non-doped blue device (476 nm) shows maximium efficiencies (current efficiency (ηc)-4.23 cd/A; power efficiency (ηp)-2.86 lm/W; external quantum efficiency (ηex)-3.48%: CIE (0.16, 0.17) at 3.10 V. Among the doped blue devices, An(PPI)2:ASPINC shows high efficiencies (ηc-12.13 cd/A; ηp-5.98 lm/W; ηex-6.79%; L-23986 cd m?2; EL-458 nm) at 3.15 V with CIE (0.15, 0.17) than An(PPI)2:PSPINC based device which is inconsistent with non-doped device performances. The green and red PhOLEDs show higher efficiencies with Ir(ppy)3: ASPINC (ηc-50.6 cd/A; ηp-53.4 lm/W; ηex-17.0%; L-61581 cd m?2; EL-501 nm, CIE (0.31, 0.60) at 3.32 V and (bt)2Ir(dipba): ASPINC (ηc-15.2 cd/A; ηp-16.5 lm/W; ηex-14.5%; L-13456 cd m?2; EL-610 nm), CIE (0.63, 0.36) at 3.20 V, respectively. The complete energy transfer between the host and dopant molecules improved the efficiency of PHOLEDs.
关键词： asymmetrically twisted phenanthrimidazole derivatives,electroluminescent properties,energy transfer,blue OLEDs,deep-blue emission
更新于2025-09-11 14:15:04
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[IEEE 2019 26th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) - Kyoto, Japan (2019.7.2-2019.7.5)] 2019 26th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) - Recent Progress in Inverted OLEDs: Mechanism of Electron Injection without Use of Alkali Metals
摘要： Inverted organic light-emitting diodes (iOLEDs) without the use of alkali metals have attracted extensive attention owing to the demand for the realization of flexible OLEDs that do not require stringent encapsulation; however, the advantage of iOLEDs and the device physics in iOLEDs have seldom been discussed. We show the advantage of iOLEDs over the conventional OLEDs from the fact that the luminance of a conventional-OLED-based flexible display decreases rapidly, whereas our iOLED-based flexible display exhibits approximately half of its initial luminance even after about 392 d. Electrons are injected into iOLEDs effectively by utilizing the solution process and a suitable dopant that can reduce the surface work function.
关键词： air stability,flexible displays,Inverted OLEDs,electron injection,alkali metals
更新于2025-09-11 14:15:04
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Highly efficient TADF OLEDs with low efficiency roll-off based on novel acridine–carbazole hybrid donor-substituted pyrimidine derivatives
摘要： Dimethyl acridine (Ac) and carbazole (Cz) donors are fused to produce acridine–carbazole hybrid donors, 12AcCz (8,8-dimethyl-5-phenyl-8,13-dihydro-5H-indolo[2,3-c]acridine) and 23AcCz (13,13-dimethyl-7-phenyl-7,13-dihydro-5H-indolo[3,2-b]acridine). By combining TPPM (2,4,6-triphenylpyrimidine) acceptor with the Ac–Cz-fused donors of 12AcCz and 23AcCz, two emitters, 12AcCz-PM (13-(4-(2,6-diphenylpyrimidin-4-yl)phenyl)-8,8-dimethyl-5-phenyl-8,13-dihydro-5H-indolo[2,3-c]acridine) and 23AcCz-PM (5-(4-(2,6-diphenylpyrimidin-4-yl)phenyl)-13,13-dimethyl-7-phenyl-7,13-dihydro-5H-indolo[3,2-b]acridine), are designed and synthesized. The impact of the different fused topologies of the hybrid donors on molecular configuration, photophysical and optoelectrical characters are systematically investigated. For 12AcCz-PM, the large steric hindrance between donor and acceptor compels Ac of 12AcCz to be crooked, which endows it with the relatively planar quasi-axial conformation. No blatant TADF character is observed, but the 12AcCz-PM doped device still presents the ultradeep blue emission with CIEx, y of (0.15, 0.05) and maximum external quantum efficiency (EQEmax) of 6.4%. Whereas, 23AcCz-PM shows quasi-equatorial conformation and possesses notable TADF behavior. The 23AcCz-PM doped device reachs the EQEmax of 28.4% at low dopant concentration and 26.1% at high dopant concentration. Additionally, low efficiency roll-off (EQEs of 24.8% at 1000 cd m-2 and 20.7% at 5000 cd m-2) further confirms its superiorities as a TADF emitter.
关键词： novel acridine–carbazole hybrid donors,highly efficient TADF OLEDs,low efficiency roll-off,thermally activated delayed fluorescence
更新于2025-09-11 14:15:04
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TOF‐SIMS MS/MS Depth Profiling of OLED Devices for Elucidating the Degradation Process
摘要： Rationale: OLED products based on display applications have become popular in the past 10 years, and new products are being commercialized with rapid frequency. Despite the many advantages of OLEDs, these devices still have a problem concerning lifetime. To gain an understanding of the degradation process, the authors have investigated the molecular information on deteriorated OLED devices using TOF-SIMS. Methods: TOF-SIMS depth profiling is an indispensable way to evaluate OLED devices. However, the depth profiles of OLEDs are generally difficult due to the mass interference among organic compounds, including degradation products. In this study, the MS/MS depth profiling method was used to characterize the OLED devices. Results: After the degradation, the defects which were comprised of small hydrocarbons were observed. Within the defect area, the diffusion of all OLED compounds were also observed. It is supposed that the source of small hydrocarbons derives from decomposition of the OLED compounds and/or contaminant at the ITO interface. Conclusions: The true compound distributions have been discovered by MS/MS depth profiling methods. The results suggest that the luminance decay is mainly due to the decomposition and diffusion of OLED compounds, and that OLED decomposition may be accelerated by adventitious hydrocarbons present at the ITO surface.
关键词： OLEDs,MS/MS Depth profiling,TOF-SIMS,Tandem MS
更新于2025-09-11 14:15:04
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Self-Catalytic-Grown SnOx Nanocones for Light Outcoupling Enhancement in Organic Light-Emitting Diodes
摘要： Light extraction in organic light-emitting diodes (OLEDs) was improved by applying SnOx nanocones grown via thermal annealing in a low-O2 atmosphere. SnOx was easily fabricated through thermal processing after Sn deposition. The diameter of the SnOx nanocones was controlled by changing the deposition thickness of Sn. The SnOx nanocones induced strong Mie scattering, which reduced the total internal reflection in the glass substrate. Consequently, the OLED with SnOx nanocones exhibited a 23% increase in the external quantum efficiency compared with a reference device.
关键词： Mie scattering,SnOx nanostructure,light extraction,organic light-emitting diodes (OLEDs),FDTD simulation
更新于2025-09-11 14:15:04
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Effect of the Host on Deep-Blue Organic Light-Emitting Diodes Based on a TADF Emitter for Roll-Off Suppressing
摘要： To achieve significant efficiency and low roll-off in thermally activated delayed fluorescence (TADF) material organic light-emitting diodes (OLEDs), it is essential to choose a host that has suitable high triplet energy (T1) and bipolar character to boost the TADF characteristics as a dopant and avoid exciton annihilation. Herein, we present the effect of different host materials on the efficiency of organic light-emitting diodes (OLEDs) based on bis[4-(3,6 dimethoxycarbazole)phenyl]sulfone (DMOC-DPS) deep-blue emitter. The devices with 10 wt.% of an emitter in different electron types of host bis[2-(diphenylphosphino) phenyl] ether oxide (DPEPO), and hole types of host 1,3-bis(N-carbazolyl)benzene (mCP), were fabricated to study the effect on device performance. The results show that an external quantum efficiency (EQE) of 4% and maximum current efficiency (ηc) up to 5.77 cd/A with high luminescence (lmax) 8185 cd/m2 in DPEPO was achieved, compared to 2.63% EQE, ηc 4.12 cd/A with lmax 5338 cd/m2 in mCP in a very simple device structure. As a remarkable result, the roll-off is suppressed at 1000 cd/m2, and for maximum brightness, the roll-off is less than 50%. Further general applications are discussed.
关键词： host,roll-off,OLEDs,TADF,DMOC-DPS
更新于2025-09-11 14:15:04
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Understanding Solid-State Solvation-Enhanced Thermally Activated Delayed Fluorescence Using a Descriptor-Tuned Screened Range-Separated Functional
摘要： An efficient computational protocol suitable for both solutions and solid films can accelerate the development of efficient thermally activated delayed fluorescence (TADF) emitters aimed at practical application in organic light-emitting diodes (OLEDs). By employing the localized orbital locator (LOL), we establish an efficient descriptor-tuning methodology for the range-separated (RS) and screened range-separated (SRS) functionals with only one single-point calculation. This scheme provides good predictions for 28 charge transfer (CT)-type TADF emitters. Moreover, in comparison to the experimental data, the scheme presents a mean absolute deviation of 0.09 eV for the absorption energies of the lowest excited singlet state (EVA(S1)) in polarizable continuum model (PCM) solution and 0.10 eV for the energy difference between the lowest excited singlet and triplet states (ΔEST) under static solid-state polarization. Importantly, our results indicate that a significantly polarized S1 is key to realizing the so-called solid-state solvation-enhanced (SSSE)-TADF, which is well captured through the screened RS functionals combined with LOL-tuning (SLOL-tuning). Compared with standard ionization potential (IP)-tuning, our scheme significantly reduces the computational cost of the prediction of singlet- and triplet-transition energies for CT molecules. It also provides a reliable approach to evaluate the practical TADF character influenced by solid-state solvation in amorphous organic thin films.
关键词： Thermally Activated Delayed Fluorescence,Optical,Solid-State Solvation-Enhanced,Plasmonics,Magnetic,Hybrid Materials,TADF,Range-Separated Functional,LOL-tuning,OLEDs
更新于2025-09-11 14:15:04
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Efficient Deep-Blue Electrofluorescence with an External Quantum Efficiency Beyond 10%
摘要： The design of blue fluorescent materials combining both deep-blue emission (CIEy<0.06) and high-efficiency climbing over the typically limited exciton production efficiency of 25% is a challenge for organic light-emitting diodes (OLEDs). In this work, we have synthesized two blue luminogens, trans-9,10-bis(2-butoxyphenyl)anthracene (BBPA) and trans-9,10-bis (2,4-dimethoxyphenyl)anthracene with high photoluminescence quantum yields (PLQYs) of 89.5% and 87.0%, respectively. Intriguingly, we have proposed a strategy to avoid aggregation-caused quenching, which can effectively reduce the undesirable excimeric emission by introducing two host matrices with twisted molecular structure, 9,10-di(naphth-2-yl) anthracene and 10,100-bis-(4-fluorophenyl)-3,30-dimethyl-9,90-bianthracene (MBAn-(4)-F), in the BBPA emission layer. The device containing the EML of BBPA-doped MBAn-(4)-F exhibited a high external quantum efficiency of 10.27% for deep-blue emission with the Commission International de L’Eclairage CIE coordinates of (0.15, 0.05) via the steric effect. Importantly, this represents an advance in deep-blue-emitting fluorescent OLED architectures and materials that meet the requirements of high-definition display.
关键词： external quantum efficiency,deep-blue emission,fluorescent materials,OLEDs,steric effect
更新于2025-09-10 09:29:36
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In-Planar-Electrodes Organic Light-Emitting Devices for Smart Lighting Applications
摘要： Smart lighting systems have earned an irreplaceable position in fields such as health care, communication, and garden cultivation. Inorganic light-emitting diode (LED) illuminant, as a traditional and well-developed field, is suitable for smart lighting systems and widely researched. However, smart lighting systems with organic light-emitting device (OLED) illuminant are rare. The key issue is to fabricate an efficient OLED illuminant with tunable spectra and intensity. Here, in-planar-electrodes OLEDs (IPE-OLEDs), which could be a possible solution to OLED illuminant used in smart lighting systems, is presented. By utilizing Mg:Ag thin film to connect two regular OLEDs with novel electron transporting layer, efficient and easy-to-fabricate IPE-OLEDs with high brightness and low voltage are achieved. The working mechanism of the IPE-OLEDs is discussed. The IPE-OLEDs can be easily driven with alternating current signals to independently address each emissive sub-cell. Thus, the OLED illuminant based on IPE-OLEDs enables adjustment of color temperature and intensity. To exhibit the features of the fabricated IPE-OLEDs further, a simple but effective smart lighting system containing IPE-OLEDs and gas detector is constructed, which could be used in the mining industry.
关键词： planar electrodes,OLEDs,color-tunable,alternating current,smart lighting
更新于2025-09-10 09:29:36
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Designing the Next Generation of Light-Emitting Electrochemical Cells
摘要： In this article, the recent achievements toward the next generation of LECs are summarized. The term next generation is founded on the impressive efforts of the scientific community to open up different pathways to enrich the library of suitable emitters for LECs with the long-term aim to meet the requirements of green photonics, that is, low-cost, high-performing, and thin-film lighting sources based on environmentally friendly and abundant materials. As an example, small molecules featuring TADF are considered the third generation of electroluminescent materials in OLEDs. Unlike this type of lighting devices, several groups have shown that LECs feature moderate performances in terms of luminance and efficacy values compared to OLEDs, but this technology bears a great future potential due to (i) the simple device architecture and active layer composition, (ii) the intolerance to the type of substrates and deposition techniques, and (iii) the good performance under ambient conditions.
关键词： green photonics,LECs,OLEDs,electroluminescent materials,Light-emitting electrochemical cells
更新于2025-09-10 09:29:36