Ultrahigh-efficiency solution-processed simplified small-molecule organic light-emitting diodes using universal host materials

Han, Tae‐Hee; Choi, Miri; Jeon, Chan-Woo; Kim, Yun‐Hi; Kwon, Soon‐Ki; Lee, Tae‐Woo

doi:10.1126/sciadv.1601428

Cited by 126 publications

(65 citation statements)

References 52 publications

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“…8 The recent publication on high efficiency solution processed smallmolecule phosphorescent OLEDs reported that the devices comprising the homoleptic Ir(ppy) 3 complex had EQEs greater than 20%. 16 Given the preponderence of reports that state Ir(ppy) 3 is an isotropic emitter, the higher EQE must be due to an optical cavity effect. In this work, we have also considered the out-coupling of the light generated in the device for both the neat and blended emissive films.…”

Section: Discussionmentioning

confidence: 99%

“…There has been a recent report of solution processed phosphorescent OLEDs with EQEs greater than 20%. 16 The OLEDs contain a graded hole injection layer, an emissive layer comprised of the emitter, hole and electron transport materials, with an additional electron transport layer (ETL) between the emissive layer and the cathode. Remarkably, the high EQEs were observed for both a homoleptic isotropic emitter [Ir(ppy) 3 ] as well as two heteroleptic complexes, with the results somewhat at odds with previously published work on dipole alignment for enhanced emission.…”

Section: Introductionmentioning

confidence: 99%

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An external quantum efficiency of >20% from solution-processed poly(dendrimer) organic light-emitting diodes

et al. 2018

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Controlling the orientation of the emissive dipole has led to a renaissance of organic light-emitting diode (OLED) research, with external quantum efficiencies (EQEs) of >30% being reported for phosphorescent emitters. These highly efficient OLEDs are generally manufactured using evaporative methods and are comprised of small-molecule heteroleptic phosphorescent iridium(III) complexes blended with a host and additional layers to balance charge injection and transport. Large area OLEDs for lighting and display applications would benefit from low-cost solution processing, provided that high EQEs could be achieved. Here, we show that poly(dendrimer)s consisting of a non-conjugated polymer backbone with iridium(III) complexes forming the cores of firstgeneration dendrimer side chains can be co-deposited with a host by solution processing to give highly efficient devices. Simple bilayer devices comprising the emissive layer and an electron transport layer gave an EQE of >20% at luminances of up to ≈300 cd/ m 2 , showing that polymer engineering can enable alignment of the emissive dipole of solution-processed phosphorescent materials.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An external quantum efficiency of >20% from solution-processed poly(dendrimer) organic light-emitting diodes

et al. 2018

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“…In particular, OLEDs have been paid considerable attention to in the academic and industrial sectors due to their promising characteristics as color display, high flexibility, low driving voltage, fast response time which empower its use in a broad range of applications such as solid‐state lighting technology and next generation flat‐panel displays . Nowadays, there are two main types of organic compounds as light‐emitting materials (EM) in the OLED technology: semiconducting polymers and small molecules . The solution‐processed OLEDs based on small conjugated molecules are attracting considerable interest because they combine the advantage of both classes simplicity of fabrication and ease of purification, characteristics for conjugated polymers or for small molecules, respectively.…”

Section: Introductionmentioning

confidence: 99%

Self‐Assembling Azaindole Organogel for Organic Light‐Emitting Devices (OLEDs)

Martín

Kennes

Auweraer

et al. 2017

Adv Funct Materials

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This study reports on the use of a self-assembling organogel, 5-(4-nonylphenyl)-7-azaindole (1), as a new emitter in small-molecule organic light emitting devices (OLEDs). The theoretical calculations along with the photophysical characterization studies suggest the coexistence of the monomer and dimer species at high concentration of compound 1. The presence of this type of dimer (formed via H-bonding) is responsible for the increased emission. However, the most notable feature is the 3D network of vastly interconnected fibers formed in the organogel that modifies the photophysical properties. Based on this, several OLED architectures are made in order to understand the mechanism involved in the electroluminescence (EL) behavior of 1. Although the position of the EL spectra differs from that of the photoluminescence (PL) spectra, the trends observed in the device properties perfectly match with dimer formation. In this framework a better device performance is associated to a higher efficiency of dimer formation, which optimizes in the OLED prepared from the organogel. Therefore, these results show that the rational combination of a moiety showing a strong PL intensity increased upon aggregation with organogel properties is an efficient strategy to create alternative emitters for OLED devices.

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“…[13][14][15][16] Good results have been obtained also via solution processing TADF small molecules and TADF exciplex hosts doped with fluorescent or phosphorescent emitters. [17][18][19][20][21][22] Here we demonstrate excellent efficiency from a simple TADF exciplex layer acting as the emitter in a device.…”

Section: Introductionmentioning

confidence: 76%

Solution processable small molecule based TADF exciplex OLEDs

Colella

Pander

Monkman

2018

Organic Electronics

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In this work we report the optimisation of the solution processable TADF exciplex emitter in OLED devices formed by the small molecules 9-[2,8]-9-carbazole-[dibenzothiophene-S,S-dioxide]-carbazole (DCz-DBTO2) and 4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine] (TAPC). This exciplex, previously reported by Jankus et al. [1], has gave vacuum deposited devices having respectively current efficiency, power efficiency and EQE of 32.3 cd/A, 26.7 lm/W and 10.3 % obtained for with DCz-DBTO2:TAPC wt% ratio of 30:70. In this work we optimised the thickness and ratio of the exciplex layer using two different solvents, chlorobenzene and chloroform. The best results were achieved when the two solvents were mixed, adding 5 vol% of chlorobenzene to chloroform. With this solvent mixture comparable results to evaporated devices were achieved, 27.5 ± 3.5 cd/A, 16.5 ± 2.0 lm/W and EQE of 8.9 ± 0.6 % at the same DCz-DBTO2:TAPC wt% ratio of 30:70, demonstrating the suitability of small molecule TADF exciplexes as solution processable emissive layer for OLEDs. Highlights  Demonstrated the suitability of TADF exciplex DCz-DBTO2:TAPC for solution processable OLED emitter.  Best results were achieved with chlorobenzene:chloroform solvent mixture with a 5:95 vol% ratio.  EQE as high as 8.9 ± 0.6% were obtained which is comparable with the results previously published for the same TADF exciplex system for vacuum deposited devices.

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Ultrahigh-efficiency solution-processed simplified small-molecule organic light-emitting diodes using universal host materials

Abstract: Researchers achieved ultrahigh efficiency of solution-processed simplified small-molecule OLEDs that use novel universal host materials.

Cited by 126 publications

References 52 publications

An external quantum efficiency of >20% from solution-processed poly(dendrimer) organic light-emitting diodes

An external quantum efficiency of >20% from solution-processed poly(dendrimer) organic light-emitting diodes

Self‐Assembling Azaindole Organogel for Organic Light‐Emitting Devices (OLEDs)

Solution processable small molecule based TADF exciplex OLEDs

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