Browse
Submit Data
Databases
API
Help

Dataset Information

19 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Efficient and stable sky-blue delayed fluorescence organic light-emitting diodes with CIE_y below 0.4.

ABSTRACT: Organic light-emitting diodes utilizing thermally activated delayed fluorescence is a potential solution for achieving stable blue devices. Sky-blue devices (CIE_y < 0.4) with high stability and high external quantum efficiency (>15%) at 1000 cd m^-2 based on either delayed fluorescence or phosphorescence are still limited and very hard to achieve simultaneously. Here, we report the design and synthesis of a new thermally activated delayed fluorescence emitter, 3Ph₂CzCzBN. A sky-blue device based on 3Ph₂CzCzBN exhibits a high external quantum efficiency of 16.6% at 1000 cd m^-2. The device shows a sky-blue electroluminescence of 482 nm and achieves Commission Internationale de l' Eclairage coordinates of (0.17, 0.36). The sky-blue device exhibits a superb LT₉₀ of 38 h. This is the first demonstration of high-efficiency and stable sky-blue devices (CIE_y < 0.4) based on delayed fluorescence, which represents an important advance in the field of blue organic light-emitting diode technology.

SUBMITTER: Chan CY

PROVIDER: S-EPMC6261989 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Pyrenylpyridines: Sky-Blue Emitters for Organic Light-Emitting Diodes.

Project description:A novel sky-blue-emitting tripyrenylpyridine derivative, 2,4,6-tri(1-pyrenyl)pyridine (2,4,6-TPP), has been synthesized using a Suzuki coupling reaction and compared with three previously reported isomeric dipyrenylpyridine (DPP) analogues (2,4-di(1-pyrenyl)pyridine (2,4-DPP), 2,6-di(1-pyrenyl)pyridine (2,6-DPP), and 3,5-di(1-pyrenyl)pyridine (3,5-DPP)). As revealed by single-crystal X-ray analysis and computational simulations, all compounds possess highly twisted conformations in the solid state with interpyrene torsional angles of 42.3°-57.2°. These solid-state conformations and packing variations of pyrenylpyridines could be correlated to observed variations in physical characteristics such as photo/thermal stability and spectral properties, but showed only marginal influence on electrochemical properties. The novel derivative, 2,4,6-TPP, exhibited the lowest degree of crystallinity as revealed by powder X-ray diffraction analysis and formed amorphous thin films as verified using grazing-incidence wide-angle X-ray scattering. This compound also showed high thermal/photo stability relative to its disubstituted analogues (DPPs). Thus, a nondoped organic light-emitting diode (OLED) prototype was fabricated using 2,4,6-TPP as the emissive layer, which displayed a sky-blue electroluminescence with Commission Internationale de L'Eclairage (CIE) coordinates of (0.18, 0.34). This OLED prototype achieved a maximum external quantum efficiency of 6.0 ± 1.2% at 5 V. The relatively high efficiency for this simple-architecture device reflects a good balance of electron and hole transporting ability of 2,4,6-TPP along with efficient exciton formation in this material and indicates its promise as an emitting material for design of blue OLED devices.

| S-EPMC6796915 | biostudies-literature

Color-stable highly luminescent sky-blue perovskite light-emitting diodes.

Project description:Perovskite light-emitting diodes (PeLEDs) have shown excellent performance in the green and near-infrared spectral regions, with high color purity, efficiency, and brightness. In order to shift the emission wavelength to the blue, compositional engineering (anion mixing) and quantum-confinement engineering (reduced-dimensionality) have been employed. Unfortunately, LED emission profiles shift with increasing driving voltages due to either phase separation or the coexistence of multiple crystal domains. Here we report color-stable sky-blue PeLEDs achieved by enhancing the phase monodispersity of quasi-2D perovskite thin films. We selected cation combinations that modulate the crystallization and layer thickness distribution of the domains. The perovskite films show a record photoluminescence quantum yield of 88% at 477?nm. The corresponding PeLEDs exhibit stable sky-blue emission under high operation voltages. A maximum luminance of 2480?cd?m-2 at 490?nm is achieved, fully one order of magnitude higher than the previous record for quasi-2D blue PeLEDs.

| S-EPMC6117319 | biostudies-literature

Efficient sky-blue perovskite light-emitting diodes via photoluminescence enhancement.

Project description:The efficiencies of green and red perovskite light-emitting diodes (PeLEDs) have been increased close to their theoretical upper limit, while the efficiency of blue PeLEDs is lagging far behind. Here we report enhancing the efficiency of sky-blue PeLEDs by overcoming a major hurdle of low photoluminescence quantum efficiency in wide-bandgap perovskites. Blending phenylethylammonium chloride into cesium lead halide perovskites yields a mixture of two-dimensional and three-dimensional perovskites, which enhances photoluminescence quantum efficiency from 1.1% to 19.8%. Adding yttrium (III) chloride into the mixture further enhances photoluminescence quantum efficiency to 49.7%. Yttrium is found to incorporate into the three-dimensional perovskite grain, while it is still rich at grain boundaries and surfaces. The yttrium on grain surface increases the bandgap of grain shell, which confines the charge carriers inside grains for efficient radiative recombination. Record efficiencies of 11.0% and 4.8% were obtained in sky-blue and blue PeLEDs, respectively.

| S-EPMC6904584 | biostudies-literature

High-Efficiency Diphenylpyrimidine Derivatives Blue Thermally Activated Delayed Fluorescence Organic Light-Emitting Diodes.

Project description:Organic light-emitting diodes with thermally activated delayed fluorescence emitter have been developed with highly twisted donor-acceptor configurations and color-pure blue emitters. Synthesized 4-(4-(4,6-diphenylpyrimidin-2-yl)phenyl)-10H-spiro[acridine-9,9'-fluorene] (4,6-PhPMAF) doped device with spiroacridine as a donor unit and diphenylpyrimidine as acceptor exhibits the device characteristics such as the luminescence, external quantum efficiencies, current efficiencies, and power efficiencies corresponding to 213 cd/m2, 2.95%, 3.27 cd/A, and 2.94 lm/W with Commission International de l'Eclairage (CIE) coordinates of (0.15, 0.11) in 4,6-PhPMAF-doped DPEPO emitter. The reported 10-(4-(2,6-diphenylpyrimidin-4-yl)phenyl)-10H-spiro[acridine-9,9'-fluorene] (2,6-PhPMAF) doped device exhibit high device performance with 1,445 cd/m2, 12.38%, 19.6 cd/A, and 15.4 lm/W, which might be originated from increased internal quantum efficiency by up-converted triplet excitons to the singlet state with relatively smaller ?E ST of 0.17 eV and higher reverse intersystem crossing rate (k RISC) of 1.0 ×108/s in 2,6-PhPMAF than 0.27 eV and 3.9 ×107/s in 4,6-PhPMAF. Despite low performance of 4,6-PhPMAF doped device, synthesized 4,6-PhPMAF has better color purity as a deep-blue emission with y axis (0.11) than reported 2,6-PhPMAF with y axis (0.19) in CIE coordinate. The synthesized 4,6-PhPMAF has higher thermal stability of any transition up to 300°C and decomposition temperature with only 5% weight loss in 400°C than reported 2,6-PhPMAF. The maximum photoluminescence emission of 4,6-PhPMAF in various solvents appeared at 438 nm, which has blue shift about 20 nm than that of 2,6-PhPMAF, which contributes deep-blue emission in synthesized 4,6-PhPMAF.

| S-EPMC7240071 | biostudies-literature

High efficiency blue organic light-emitting diodes with below-bandgap electroluminescence.

Project description:Blue organic light-emitting diodes require high triplet interlayer materials, which induce large energetic barriers at the interfaces resulting in high device voltages and reduced efficiencies. Here, we alleviate this issue by designing a low triplet energy hole transporting interlayer with high mobility, combined with an interface exciplex that confines excitons at the emissive layer/electron transporting material interface. As a result, blue thermally activated delay fluorescent organic light-emitting diodes with a below-bandgap turn-on voltage of 2.5 V and an external quantum efficiency (EQE) of 41.2% were successfully fabricated. These devices also showed suppressed efficiency roll-off maintaining an EQE of 34.8% at 1000 cd m-2. Our approach paves the way for further progress through exploring alternative device engineering approaches instead of only focusing on the demanding synthesis of organic compounds with complex structures.

| S-EPMC8357948 | biostudies-literature

Interfacial "Anchoring Effect" Enables Efficient Large-Area Sky-Blue Perovskite Light-Emitting Diodes.

Project description:While tremendous progress has recently been made in perovskite light-emitting diodes (PeLEDs), large-area blue devices feature inferior performance due to uneven morphologies and vast defects in the solution-processed perovskite films. To alleviate these issues, a facile and reliable interface engineering scheme is reported for manipulating the crystallization of perovskite films enabled by a multifunctional molecule 2-amino-1,3-propanediol (APDO)-triggered "anchoring effect" at the grain-growth interface. Sky-blue perovskite films with large-area uniformity and low trap states are obtained, showing the distinctly improved radiative recombination and hole-transport capability. Based on the APDO-induced interface engineering, synergistical boost in device performance is achieved for large-area sky-blue PeLED (measuring at 100 mm2 ) with a peak external quantum efficiency (EQE) of 9.2% and a highly prolonged operational lifetime. A decent EQE up to 6.1% is demonstrated for the largest sky-blue device emitting at 400 mm2 .

| S-EPMC8498857 | biostudies-literature

An Alternative Host Material for Long-Lifespan Blue Organic Light-Emitting Diodes Using Thermally Activated Delayed Fluorescence.

Project description:It has been challenging to find stable blue organic light emitting diodes (OLEDs) that rely on thermally activated delayed fluorescence (TADF). Lack of stable host materials well-fitted to the TADF emitters is one of the critical reasons. The most popular host for blue TADF, bis[2-(diphenylphosphino)phenyl] ether oxide (DPEPO), leads to unrealistically high maximum external quantum efficiency. DPEPO is however an unstable material and has a poor charge transporting ability, which in turn induces an intrinsic short OLED operating lifespan. Here, an alternative host material is introduced which educes the potential efficiency and device lifespan of given TADF emitters with the appropriateness of replacing the most popular host material, DPEPO, in developing blue TADF emitters. It simultaneously provides much longer device lifespan and higher external quantum efficiency at a practical brightness due to its high material stability and electron-transport-type character well-fitted for hole-transport-type TADF emitters.

| S-EPMC5566347 | biostudies-literature

High-Performance Nondoped Blue Delayed Fluorescence Organic Light-Emitting Diodes Featuring Low Driving Voltage and High Brightness.

Project description:Thermally activated delayed fluorescence (TADF) provides great potential for the realization of efficient and stable organic light-emitting diodes (OLEDs). However, it is still challenging for blue TADF emitters to simultaneously achieve high efficiency, high brightness, and low Commission Internationale de l'Eclairage (CIE) y coordinate (CIEy) value. Here, the design and synthesis of two new benzonitrile-based TADF emitters (namely 2,6-di(9H-carbazol-9-yl)-3,5-bis(3,6-diphenyl-9H-carbazol-9-yl)benzonitrile (2PhCz2CzBn) and 2,6-di(9H-carbazol-9-yl)-3,5-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)benzonitrile (2tCz2CzBn)) with a symmetrical and rigid heterodonor configuration are reported. The TADF OLEDs doped with both the emitters can achieve a high external quantum efficiency (EQE) over 20% and narrowband blue emission of 464 nm with a CIEy < 0.2. Moreover, the incorporation of a terminal tert-butyl group can weaken the intermolecular ?-? stacking in the nondoped TADF emitter, and thus significantly suppress self-aggregation-caused emission quenching for enhanced delayed fluorescence. A peak EQE of 21.6% is realized in the 2tCz2CzBn-based nondoped device with an extremely low turn-on voltage of 2.7 V, high color stability, a high brightness over 20 000 cd m-2, a narrow full-width at half-maximum of 70 nm, and CIE color coordinates of (0.167, 0.248).

| S-EPMC7001635 | biostudies-literature

Blue organic light-emitting diodes realizing external quantum efficiency over 25% using thermally activated delayed fluorescence emitters.

Project description:Improving the performance of blue organic light-emitting diodes (OLEDs) is needed for full-colour flat-panel displays and solid-state lighting sources. The use of thermally activated delayed fluorescence (TADF) is a promising approach to efficient blue electroluminescence. However, the difficulty of developing efficient blue TADF emitters lies in finding a molecular structure that simultaneously incorporates (i) a small energy difference between the lowest excited singlet state (S1) and the lowest triplet state (T1), ΔE ST, (ii) a large oscillator strength, f, between S1 and the ground state (S0), and (iii) S1 energy sufficiently high for blue emission. In this study, we develop TADF emitters named CCX-I and CCX-II satisfying the above requirements. They show blue photoluminescence and high triplet-to-singlet up-conversion yield. In addition, their transition dipole moments are horizontally oriented, resulting in further increase of their electroluminescence efficiency. Using CCX-II as an emitting dopant, we achieve a blue OLED showing a high external quantum efficiency of 25.9%, which is one of the highest EQEs in blue OLEDs reported previously.

| S-EPMC5428273 | biostudies-literature

Achieving Deep-Blue Thermally Activated Delayed Fluorescence in Nondoped Organic Light-Emitting Diodes through a Spiro-Blocking Strategy.

Project description:A deep-blue thermally activated delayed fluorescence (TADF) emitter TXADO-spiro-DMACF has been reported for nondoped organic light-emitting diodes (OLEDs) by integrating an appropriate blocking unit with the donor (D)-acceptor (A)-donor (D)-type TADF emitter via a spiro linkage. Benefiting from the characteristic perpendicular arrangement, the intermolecular interactions are expected to be weakened to some degree. As a result, TXADO-spiro-DMACF shows a very small bathochromic shift of 8 nm associated with a narrowed full width at half maximum of 54 nm on going from solution to the film. The corresponding nondoped device successfully achieves a bright deep-blue emission, revealing Commission Internationale de l'Eclairage coordinates of (0.16, 0.09) and a peak external quantum efficiency of 5.3% (5.3 cd/A, 5.9 lm/W). The results clearly indicate that spiro-blocking is a promising strategy to develop deep-blue TADF emitters capable of nondoped OLEDs.

| S-EPMC6648766 | biostudies-literature