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Efficient inkjet-printed blue OLED with boosted charge transport using host doping for application in pixelated display
摘要： Inkjet-printing is a desirable technology for organic light emitting diodes (OLEDs) owing to its compatibility with large-area low-cost full-color pixelated displays. In this work, we proposed a strategy to fabricate highly efficient inkjet-printed blue OLEDs by introducing 3,5-bis(N-car-bazolyl)benzene (mCP) as the host material into organic light emitting layers. By carefully tailoring the weight ratio of mCP to poly[(9,9-dioctyl-2,7-fluorene)-co-(dibenzothiophene-S,S-dioxide)] (PFSO), the device demonstrated superior charge transport capability, leading to balanced charge transport and optimized efficiency. Furthermore, in combination with modifying the mCP: PFSO ink formulation, a low-roughness organic emissive film on Poly(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) layer was achieved. The performance of the inkjet-printed device has been significantly improved with nearly five times, which exhibits a maximum luminance and an external quantum efficiency of 3743 cd/m2 and 5.03%, respectively. The icing on the cake is that we fabricated a 3-inch blue OLED array device successfully with a brightness uniformity of 92.7%, which shows promising potential in realizing simple structure large-area and high-efficient OLEDs by inkjet printing.
关键词： Blue,Organic light emitting diodes,Charge transport,Inkjet-printing
更新于2025-09-23 15:19:57
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All-fluorescent white organic light-emitting diodes with EQE exceeding theoretical limit of 5% by incorporating a novel yellow fluorophor in co-doping forming blue exciplex
摘要： For all-fluorescent white organic light-emitting diodes (WOLEDs), it is a current challenge to achieve comparable device efficiency to phosphorescent devices. A novel yellow fluorophor (Y), synthesized by our group, realizes ultra-high electroluminescence performance with maximum luminance and external quantum efficiency (EQE) reaching 74820 cd/m2 and 5.65%, respectively, indicating a huge potential applications in developing high-performance all-fluorescent WOLEDs. Herein, we employ above yellow emitter Y to demonstrate a series of all-fluorescent WOLEDs, where the devices are fabricated by doping yellow emitter Y in blue-emitting thermally activated delayed fluorescent (TADF) host of mCP:PO-T2T-forming exciplex. And white emission are realized by the combination of blue and yellow emissions from mCP:PO-T2T host and yellow emitter Y through the incomplete energy transfer. By simply adjusting the doping ratio of yellow emitter Y in mCP:PO-T2T host, the optimized all-fluorescent white device achieves high device performance with maximum current efficiency, power efficiency, and EQE reaching 20.78 cd/A , 24.25 lm/W, and 8.22%, respectively. The EQE obviously exceed the theoretical limit value of 5% for all-fluorescent WOLEDs, and is comparable to some fluorescent/phosphorescent or all-phosphorescent WOLEDs in reported literatures. The achievement of such high performance is mainly ascribed to the highly efficient exciton utilization derived from excellent yellow fluorescent emitter Y and effective reverse intersystem crossing (RISC) from triplet level to singlet level in mCP:PO-T2T exciplex host.
关键词： white emission,exciplex host,all-fluorescent emission,organic light-emitting diodes,external quantum efficiency
更新于2025-09-23 15:19:57
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Regioisomer effects of dibenzofuran-based bipolar host materials on yellow phosphorescent OLED device performance
摘要： Four regioisomers were synthesized for use as bipolar host materials for phosphorescent organic light-emitting diodes (PhOLEDs) by classic cross-coupling reactions using cyanofluorene and fused dibenzofuran and were readily purified. To realize the bipolar host material, a cyano-substituted fluorene was selected as the n-type unit and dibenzofuran as the p-type unit. Yellow PhOLEDs were fabricated with iridium(III) bis(4-phenylthieno[3,2-c]pyridinato-N,C20)acetylacetonate [PO-01] as a phosphorescent emitter. The achieved maximum current efficiency was 77.2 cd A?1 and the external quantum efficiency was 25.3% for the [PO-01]-based PhOLED; the 7-(dibenzo[b,d]furan-2-yl)-9,9-dimethyl-9H-fluorene-2-carbonitrile (CF-2-BzF) host had the best device performance. The color coordinates of yellow PhOLEDs at 1000 cd m?2 were (0.50, 0.50) (CF-1-BzF), (0.50, 0.49) (CF-2-BzF), (0.51, 0.49) (CF-3-BzF), and (0.50, 0.50) (CF-4-BzF).
关键词： regioisomer effects,phosphorescent organic light-emitting diodes,device performance,bipolar host materials,yellow PhOLEDs
更新于2025-09-23 15:19:57
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Tert-butyl Substituted Hetero-donor TADF compounds for Efficient Solution-Processed Non-doped Blue OLEDs
摘要： For the development of solution-processed organic light-emitting diodes (OLEDs), it is highly desirable and challenging for releazing solution-processable non-doped thermally activated delayed fluorescence (TADF) emitters due to their high efficiency and excellent compatibility to the wet methods. Herein, two pairs of blue TADF isomers are designed and synthesized with a hetero-donor configuration for the realization of high photoluminescent quantum yield. The incorporation of two tert-butyl groups in the molecules can effectively increase the molecular solubility and reduce the aggregation-caused self-quenching of excitons in neat films by inhibiting the intramolecular vibrational relaxation and the intermolecular π-π stacking. Solution-processed non-doped OLEDs are achieved with these blue TADF emitters, exhibiting the record-high external quantum efficiencies (EQE) of 25.8%. Furthermore, all-TADF white OLED with an EQE of 27.3% is also achieved by employing a single emitting layer with the blue TADF emitter as a host for an orange-red TADF dopant.
关键词： non-doped OLED,blue fluoresecent materials,Organic light-emitting diodes,solution process,thermally activated delayed fluorescence
更新于2025-09-23 15:19:57
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High-performance white organic light-emitting diodes with doping-free device architecture based on the exciton adjusting interfacial exciplex
摘要： White organic light-emitting diodes (WOLEDs) with doping-free device architecture have aroused more attention due to their attractive merits such as simplified fabrication procedures and reduced costs. However, the electroluminescence performance of that is still manifestly unsatisfactory and needs to be further improved. Here, high-performance doping-free two-color and three-color WOLEDs with the accurate manipulation of excitons have been successfully fabricated by optimizing the interfacial exciplex. As a result, two-color WOLEDs exhibit the controllable electroluminescence spectra with a wide correlated color temperature (CCT) spanning from 2878 to 9895 K at the voltage of 4 V, as well as the maximum forward-viewing power and current efficiencies of 83.2 lm W?1 and 63.3 cd A?1, respectively. The three-color WOLED not only realizes the maximum efficiencies of 50.1 lm W?1 and 44.7 cd A?1, but also exhibits superior color stability with a color rendering index of 86, a CCT of 2679 K, and a Commission International de I’Eclairage coordinates of (0.49, 0.46) at the voltage of 5 V. Such surprising efficiencies obtained in our WOLEDs indicate that the reasonable application of interfacial exciplex should be a helpful way to develop high-performance and low cost WOLEDs with a simple technology.
关键词： high-performance,color stability,White organic light-emitting diodes,doping-free,interfacial exciplex
更新于2025-09-23 15:19:57
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Diphenylamine/triazine hybrids as bipolar hosts for phosphorescent organic light-emitting diodes
摘要： The bipolar host materials employing diphenylamine (DPA) as donor unit and triazine (TRZ) as acceptor unit could achieve suitable energy levels and balanced charge transporting properties, which are necessary for high performance of organic light-emitting diodes (OLEDs). In this work, three DPA/TRZ based host materials, named 2-(4-(N,N-diphenylamino)phenyl)-4,6-diphenyl-1,3,5-triazine (DPA-TRZ), 2,4-bis(4-(N,N-diphenylamino)phenyl)-6-phenyl-1,3,5-triazine (DDPA-TRZ), and 2,4,6-tris(4-(N,N-diphenylamino)phenyl)-1,3,5-triazine (TDPA-TRZ) were designed and synthesized. Their thermal, photophysical, electrochemical, and carrier transporting properties were investigated to reveal the relationship between molecular structure and properties. The number of DPA units could regularly tune the optical and electrical properties of the hybrids. The triplet excited state energy (ET) values of DPA-TRZ, DDPA-TRZ, and TDPA-TRZ are 2.38, 2.51, and 2.73 eV, respectively. To evaluate the electroluminescent properties of the three host materials, blue, green, red, and white phosphorescent OLEDs (PhOLEDs) were fabricated and characterized. With the highest ET value, TDPA-TRZ can afford from blue to red phosphorescent emitters. All these devices exhibited EQEs of over 20% with relatively low efficiency roll-offs. The single-host white PhOLEDs based on TDPA-TRZ showed impressive color stability and superior color rendition. These results demonstrate that the combination of DPA and TRZ is an effective way to construct highly efficient bipolar host materials.
关键词： diphenylamine,triazine,phosphorescent organic light-emitting diodes,charge transporting properties,bipolar host materials
更新于2025-09-23 15:19:57
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Control of ??a???? stacking in carbazole-benzimidazo???1,2- <i>f</i> ???phenanthridines: the design of electron-transporting bipolar hosts for phosphorescent organic light-emitting diodes
摘要： Two bipolar hosts, 8-cbzBIFP and 10-cbzBIFP, both with basic skeletons of orthogonally-connected carbazole and benzimidazoh1,2-fiphenanthridine (BIFP) have been prepared. The planar structure of the BIFP moiety in comparison to the governs the molecular stacking in the crystal lattice. Electron transport properties, benzimidazole derivatives, are facilitated. Both hosts display fabulous performances in phosphorescent organic light-emitting diodes with bis(2-phenylpyridine)(acetylacetonate)iridium(III) as an emitter. The optimized green PhOLED of 10-cbzBIFP achieves the maximum brightness (Lmax) of 58 810 cd m(cid:2)2, the maximum current e?ciency (Zc) of 87.0 cd A(cid:2)1 and external quantum e?ciency (EQE) of 21.1%. Likewise, 8-cbzBIFP shows an Lmax of 58 870 cd m(cid:2)2, Zc of 77.3 cd A(cid:2)1 and EQE of 19.1%.
关键词： electron-transporting,phosphorescent organic light-emitting diodes,carbazole-benzimidazoh1,2-fiphenanthridines,bipolar hosts,p–p stacking
更新于2025-09-23 15:19:57
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Efficient Aggregation-Induced Delayed Fluorescence Luminogens for Solution-Processed OLEDs With Small Efficiency Roll-Off
摘要： Purely organic small molecules with thermally-activated delayed fluorescence have a high potential for application in organic light-emitting diodes (OLEDs), but overcoming severe efficiency roll-off at high voltages still remains challenging. In this work, we design and synthesize two new emitters consisting of electron-withdrawing benzoyl and electron-donating phenoxazine and 9,9-dihexylfluorene. Their electronic structures, thermal stability, electrochemical behaviors, photoluminescence property, and electroluminescence performance are thoroughly investigated. These new emitters show weak fluorescence in dilute solution, but they can emit strongly with prominent delayed fluorescence in the aggregated state, indicating the aggregation-induced delayed fluorescence (AIDF) character. The solution-processed OLEDs based on the two emitters show high external quantum efficiency of 14.69%, and the vacuum-deposited OLEDs can also provide comparable external quantum efficiency of 14.86%. Significantly, roll-offs of the external quantum efficiencies are very small (down to 0.2% at 1,000 cd m?2) for these devices, demonstrating the evidently advanced efficiency stability. These results prove that the purely organic emitters with AIDF properties can be promising to fabricate high-performance solution-processed OLEDs.
关键词： thermally activated delayed fluorescence,aggregation-induced fluorescence,efficiency roll-off,delayed fluorescence,organic light-emitting diodes,electroluminescence
更新于2025-09-23 15:19:57
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A negative polaron resistant p-type host for extended lifetime in deep blue phosphorescent organic light-emitting diodes
摘要： A novel mixed host employing a negative polaron stabilizing p-type host was developed to extend the device lifetime of blue phosphorescent organic light-emitting diodes (PhOLEDs). Instead of a conventional p-type host with only a hole transport unit, a p-type host with a negative polaron resistant unit in addition to the hole transport unit was used in the mixed host consisting of a p-type host and an n-type host. The p-type host had benzonitrile as a negative polaron resistant unit which stabilized the molecule under negative polarons. The use of the p-type host with the benzonitrile unit almost doubled the device lifetime of the blue PhOLEDs due to the improved negative polaron stability of the hosts. Therefore, the p-type host with the weak electron accepting benzonitrile unit can play the role of a lifetime extending p-type host to replace a conventional p-type host.
关键词： p-type host,device lifetime,negative polaron,benzonitrile,blue phosphorescent organic light-emitting diodes
更新于2025-09-23 15:19:57
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Perdeuterated conjugated polymers for ultralowa??frequency magnetic resonance of OLEDs
摘要： The formation of excitons in OLEDs is spin dependent and can be controlled by electron-paramagnetic resonance, affecting device resistance and electroluminescence yield. We explore electrically detected magnetic resonance in the regime of very low magnetic fields (< 1 mT). A pronounced feature emerges at zero field in addition to the conventional spin-1=2 Zeeman resonance for which the Larmor frequency matches that of the incident radiation. By comparing a conventional p-conjugated polymer as the active material to a perdeuterated analogue, we demonstrate the interplay between the zero-field feature and local hyperfine fields. The zero-field peak results from a quasistatic magnetic-field effect of the RF radiation for periods comparable to the carrier-pair lifetime. Zeeman resonances are resolved down to 3.2 MHz, approximately twice the Larmor frequency of an electron in Earth(cid:3)s field. However, since reducing hyperfine fields sharpens the Zeeman peak at the cost of an increased zero-field peak, we suggest that this result may constitute a fundamental low-field limit of magnetic resonance in carrier-pair-based systems. OLEDs offer an alternative solid-state platform to investigate the radical-pair mechanism of magnetic-field effects in photochemical reactions, allowing models of biological magnetoreception to be tested by measuring spin decoherence directly in the time domain by pulsed experiments.
关键词： conjugated polymers,deuteration,magnetic resonance,isotopes,organic light-emitting diodes
更新于2025-09-23 15:19:57