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Porous nanocellulose paper was fabricated and applied as a light outcoupling medium. The nanocellulose papers were prepared using cellulose powder and a high-pressure homogenizing process. The translucent nanocellulose paper had high total transmittance and haze, and gave off diffuse light when the incident light passes through it. Through the application of the fabricated nanocellulose paper on the external surfaces of organic light-emitting diode (OLED) devices, it was possible not only to enhance the luminous efficiency but also to widen the angular light distribution. As this paper is intrinsically flexible, it can be applied to various forms of light sources bearing curvature.

A simple correlation between MPRT and LC response time, TFT frame rate, and duty ratio is established. At 120-Hz frame rate, if the LC’s response time is

Organic light-emitting diodes (OLEDs) are subjected to varying conditions of temperature during their lifetime. Using a combination of neutron reflectometry and in situ photoluminescence spectroscopy we show that layers typically found in OLEDs can interdiffuse. The diffusion is temperature dependent and it is found that the iridium(III) complexes can be remarkably mobile, even with relatively bulky alkyl groups attached to the ligand.

M.C.G. acknowledges support from European Union Marie Curie Career Integration Grant (PCIG12-GA-2012-334407). E.Z.-C. acknowledges support from the Leverhulme trust (RPG-2016- 047).

—We have interfaced an array of polymer light emitting\ud diodes (OLEDs) fabricated onto a glass substrate to a sheet\ud of paper via a pressure sensitive conducting adhesive. By screen\ud printing a series of capacitive touch pads and connecting tracks\ud onto paper using a low-cost conductive graphite ink, we are able to\ud drive individual pixels in the OLED array via CMOS-based electronics\ud that are also attached to the paper. Three AA batteries are\ud used to power the CMOS electronics, touch pads and the OLED\ud array, with pixels in the array operating at a brightness of up to\ud 210 cd/m2. The work highlights a practical interface between\ud plastic- and paper-based electronics.

This paper describes the potential of hi-res display fabrication using OLED photolithography. We demonstrate 1250 ppi multicolor arrays, pixel scaling down to 3 μm pitch, integration in active displays, and improving lifetime after patterning (200 hours T75, smOLEDs). Photolithography can enable low-cost, high resolution displays for the 8K – VR era.

Detection of cocaine on the level of a few ng/ml by the use of lab-on-a-paper test co-working with OLED light source as exciatation light source and CCD-based detection unit is described in this paper. The new method enables not only yes or now answer of drug presence in a tested sample but also concentration of the drug in the sample. Presented here results opens a new way toward portable instrumentation for point-of-care detection of cocaine (and in the future other drugs) in sweat of for example professional drivers. This device will be a drug-tester similar to widely now used alcohol testers.

A device concept for highly efficient OLEDs is introduced that allows to tune the emission color of the device over a broad range of the CIE color gamut. The approach exploits the different polarities of the positive and negative half-cycles of an alternating current driving signal to independently address two vertically stacked emission units with complementary color. Ultrathin metal electrodes fabricated by a wetting layer approach are used to achieve good electrical contact to each stack with minimal impact on optical performance. Postprint Non

Tris(8-hydroxyquinolinato)aluminum(III) (Alq3) stands as one of the most successful materials used in organic light emitting devices (OLEDs) for display applications. In spite of its wide usage in these devices two key issues of the material, namely its isomerism and triplet state remained unresolved for many years. In this paper, we provide evidence for the existence of the facial isomer of Alq3 from a combination of structural, thermal and photophysical investigations. Moreover, we present experimental results on the energy and lifetime of the triplet state in Alq3.

We present a controlled, well-defined pattern replication of a micrometer template driven by a surface free energy lithographic technique, realized by molecular aggregation in dewetting conditions and by confining the liquid solution with geometric boundaries. The presented technique has allowed the fabrication of light-emitting devices, and in particular the realization of OLEDs with an array of addressable pixels.

critical elements of a-Si technology on clear plastic for flexible AMOLED applications. First, we show that a- Si TFT's with gate voltages under 5 V provide sufficient current for OLED pixel brightness of over 1000 cd/m 2 , with minimum geometries (W/L = 1) for 100 µm × 100 µm pixels. Critical to this result is a clear plastic with the combined properties of high transparency, glass transition temperature in excess of 300 o C, and low coefficient of thermal expansion. Second, we show that by engineering the a-Si TFT stack, under the bias conditions for pixel operation, the "half-life" of the TFT (defined as the time for the current to fall by 50% in DC operation) is 10 years for a 280 o C process on clear plastic, and at least 100 years for 300 o C. This is several orders of magnitude higher than that of common a-Si TFT processes and in general larger than the lifetimes for the 50% decay of the luminescence of the OLED's themselves. Finally, we provide a framework demonstrating the tradeoff between drive current and TFT stability.

A significant challenge facing human kind in the 21st Century is how to address the ever decreasing supply of depletable and renewable energy. One approach to this problem is to decrease our usage. for this reason, considerable attention has been focused on more efficient means for room lighting which currently consumes approximately 20% of the total energy used. Organic light emitting devices (OLEDs) provide a unique opportunity to provide this high efficiency solid state lighting at very low cost. In this talk, I will discuss several strategies for achieving very high efficiency white light emission at high brightnesses for the next generation of efficient solid state lighting sources based on small molecular weight, vapor deposited OLED structures. Key to our approach is the use of electrophosphorescence as a means for converting all electrical into optical energy. We show that the highest luminance efficiencies can be obtained by a combination of fluorescence and phosphorescence in a unique OLED structure. Furthermore, the highest brightnesses are achieved (without a significant loss in power efficiency) by stacking several fluorescent/phosphorescent elements in a single OLED structure (called a SOLED), with each emitting element in the stack separated by a transparent charge generation layer. Prospects for OLEDs as the next practical generation of interior illumination sources will be reviewed.

A series of four heterocyclic dimers has been synthesized, with twisted geometries imposed across the central linking bond by ortho‐alkoxy chains. These include two isomeric bicarbazoles, a bis(dibenzothiophene‐S,S‐dioxide) and a bis(thioxanthene‐S,S‐dioxide). Spectroscopic and electrochemical methods, supported by density functional theory, have given detailed insights into how para‐ vs. meta‐ vs. broken conjugation, and electron‐rich vs. electron‐poor heterocycles impact the HOMO–LUMO gap and singlet and triplet energies. Crucially for applications as OLED hosts, the triplet energy (E T) of these molecules was found to vary significantly between dilute polymer films and neat films, related to conformational demands of the molecules in the solid state. One of the bicarbazole species shows a variation in E T of 0.24 eV in the different media—sufficiently large to “make‐or‐break” an OLED device—with similar discrepancies found between neat films and frozen solution measurements of other previously reported OLED hosts. From consolidated optical and optoelectronic investigations of different host/dopant combinations, we identify that only the lower E T values measured in neat films give a reliable indicator of host/guest compatibility. This work also provides new molecular design rules for obtaining very high E T materials and controlling their HOMO and LUMO energies., A new series of high E T heterocyclic dimers has been synthesized with large dihedral angles enforced by steric hindrance. A meta‐conjugated carbazole dimer displays the highest E T of 3.07 eV in dilute polymer film, however in a neat film this falls to 2.83 eV. Similar variation is observed across the series. This work highlights that to reliably estimate host/guest compatibility, E T determined from phosphorescence of neat films must be reported for new host materials. The currently accepted practice of reporting values from frozen solution or polymer films is no substitute.

Four aryl-substituted acridan derivatives were designed, synthesized and characterized as electroactive materials for organic light emitting diodes based on emitters exhibiting thermally activated delayed fluorescence. These compounds possessed relatively high thermal stability with glass-transition temperatures being in the range of 79–97 °C. The compounds showed oxidation bands arising from acridanyl groups in the range of 0.31–038 V. Ionization potentials of the solid films ranged from 5.39 to 5.62 eV. The developed materials were characterized by triplet energies higher than 2.5 eV. The layer of 10-ethyl-9,9-dimethyl-2,7-di(naphthalen-1-yl)-9,10-dihydroacridine demonstrated hole mobilities reaching10−3 cm2/V·s at electric fields higher then ca. 2.5 × 105 V/cm. The selected compounds were used as hosts in electroluminescent devices which demonstrated maximum external quantum efficiencies up to 3.2%.

Three compounds, bearing a quinazoline unit as the acceptor core and carbazole, dimethyldihydroacridine, or phenothiazine donor moieties, were designed and synthesized in two steps including a facile copper-catalyzed cyclization and a nucleophilic aromatic substitution reaction. The photophysical properties of the compounds, based on theoretical calculations and experimental measurements, as well as the electrochemical and thermal properties, are discussed. The synthesized compounds form glasses with glass-transition temperatures ranging from 116 °C to 123 °C. The ionization potentials estimated by cyclic voltammetry of the derivatives were in the range of 5.22–5.87 eV. The 3,6-di-tert-butylcarbazole-substituted quinazoline-based compound forms a sky-blue emitting exciplex in solid mixture with the acceptor 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine as well as an orange emitting exciplex with the donor 4,4′,4″-tris[3-methylphenyl(phenyl)amino]triphenylamine. A white OLED based on these versatile exciplex systems with a relatively high maximum brightness of 3030 cd/m2 and an external quantum efficiency of 0.5% was fabricated.

A series of 9‐borafluorene derivatives, functionalised with electron‐donating groups, have been prepared. Some of these 9‐borafluorene compounds exhibit strong yellowish emission in solution and in the solid state with relatively high quantum yields (up to 73.6 % for FMesB‐Cz as a neat film). The results suggest that the highly twisted donor groups suppress charge transfer, but the intrinsic photophysical properties of the 9‐borafluorene systems remain. The new compounds showed enhanced stability towards the atmosphere, and exhibited excellent thermal stability, revealing their potential for application in materials science. Organic light‐emitting diode (OLED) devices were fabricated with two of the highly emissive compounds, and they exhibited strong yellow‐greenish electroluminescence, with a maximum luminance intensity of >22 000 cd m−2. These are the first two examples of 9‐borafluorene derivatives being used as light‐emitting materials in OLED devices, and they have enabled us to achieve a balance between maintaining their intrinsic properties while improving their stability., Luminescent boroles: Highly twisted donor‐functionalised 9‐borafluorenes have been synthesised that exhibit bright luminescence without obvious charge‐transfer character, as well as excellent thermal stability, suggesting their suitability for optoelectronic applications (see figure). Two organic light‐emitting diode devices fabricated with these compounds showed properties highly favourable for future development.

Tetraphenylethylene (TPE) and its derivatives exhibit excellent aggregation‐induced emission (AIE) properties. The TPE unit is easily accessible, and many functional groups can be introduced in a facile manner to yield effective luminescent materials in both solution and the solid‐state. It is because of this, several TPE‐based compounds have been developed and applied in many areas, such as OLEDs and chemical sensors. Boron dipyrromethenes (BODIPYs) are a class of pyrrolic fluorophore of great interest with myriad application in both material science and biomedical applications. Through the combination of Pd‐catalyzed cross‐coupling reactions and traditional dipyrromethene chemistry, we present the syntheses of novel tetra‐BODIPY‐appended TPE derivatives with different distances between the TPE and BODIPY cores. The TPE‐BODIPY arrays 6 and 9 show vastly differing AIE properties in THF/H2O systems, with 9 exhibiting dual‐AIE, along with both conjugates being found to produce singlet oxygen (1O2). We presume the synthesized BODIPY‐appended TPE scaffolds to be utilized for potential applications in the fields of light‐emitting systems and theranostics., Herein the synthesis of two novel tetra‐BODIPY tetraphenylethylene (TPE) conjugates is presented. We find differing AIE responses dependent upon the linkage between the TPE and BODIPY cores, as well as differing singlet oxygen generation of the synthesized conjugates.

In this combined experimental and theoretical study, a computational protocol is reported to predict the excited states in D‐π‐A compounds containing the B(FXyl)2 (FXyl = 2,6‐bis(trifluoromethyl)phenyl) acceptor group for the design of new thermally activated delayed fluorescence (TADF) emitters. To this end, the effect of different donor and π‐bridge moieties on the energy gaps between local and charge‐transfer singlet and triplet states is examined. To prove this computationally aided design concept, the D‐π‐B(FXyl)2 compounds 1–5 were synthesized and fully characterized. The photophysical properties of these compounds in various solvents, polymeric film, and in a frozen matrix were investigated in detail and show excellent agreement with the computationally obtained data. Furthermore, a simple structure–property relationship is presented on the basis of the molecular fragment orbitals of the donor and the π‐bridge, which minimize the relevant singlet–triplet gaps to achieve efficient TADF emitters., A combination of experiment and theory leads to new insights into accurately and cost‐efficiently predicting the phenomenon of thermally activated delayed fluorescence. The calculations guide syntheses in optimizing the energy gaps between the states of different multiplicity involved in order to develop new efficient emitter materials.

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 π–π 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)., A new blue thermally activated delayed fluorescence emitter of 2tCz2CzBn is synthesized with a symmetrical and rigid heterodonor configuration, enabling significant suppression of self‐aggregation‐caused emission quenching. High‐performance nondoped organic light‐emitting diodes are achieved with a high external quantum efficiency of 21.6%, an extremely low turn‐on voltage of 2.7 V, and narrowband blue emission.

Thermally stable, strongly luminescent gold‐TADF emitters are the clue to realize practical applications of gold metal in next generation display and lighting technology, a scarce example of which is herein described. A series of donor–acceptor type cyclometalated gold(III) alkynyl complexes with some of them displaying highly efficient thermally activated delayed fluorescence (TADF) with Φ up to 88% in thin films and emission lifetimes of ≈1–2 µs at room temperature are developed. The emission color of these complexes is readily tunable from green to red by varying the donor unit and cyclometalating ligand. Vacuum‐deposited organic light‐emitting diodes (OLEDs) with these complexes as emissive dopants achieve external quantum efficiencies (EQEs) and luminance of up to 23.4% and 70 300 cd m−2, respectively.

With the naturally separated frontier molecular orbitals, exciplexes are capable of thermally activated delayed fluorescence emitters for organic light‐emitting diodes (OLEDs). And, the current key issue for exciplex emitters is improving their exciton utilization. In this work, a strategy of building exciplex emitters with three components is proposed to realize multiple reverse intersystem crossing (RISC) channels, improving their exciton utilization by enhancing upconversion of nonradiative triplet excitons. Accordingly, a tricomponent exciplex DBT‐SADF:PO‐T2T:CDBP is constructed with three RISC channels respectively on DBT‐SADF, DBT‐SADF:PO‐T2T, and CDBP:PO‐T2T. Furthermore, its photoluminescence quantum yield and rate constant of the RISC process are successfully improved. In the OLED, DBT‐SADF:PO‐T2T:CDBP exhibits a remarkably high maximum external quantum efficiency (EQE) of 20.5%, which is the first report with an EQE over 20% for the OLEDs based on exciplex emitters to the best of our knowledge. This work not only demonstrates that introducing multiple RISC channels can effectively improve the exciton utilization of exciplex emitters, but also proves the superiority of the tricomponent exciplex strategy for further development of exciplex emitters.

The design of orange-light emitting, thermally activated, delayed fluorescence (TADF) materials is necessary and important for the development and application of organic light-emitting diodes (OLEDs). Herein, two donor–acceptor–donor (D–A–D)-type orange TADF materials based on fluorenone and acridine, namely 2,7-bis(9,9-dimethylacridin-10(9H)-yl)-9H-fluoren-9-one (27DACRFT, 1) and 3,6-bis(9,9-dimethylacridin-10(9H)-yl)-9H-fluoren-9-one (36DACRFT, 2), were successfully synthetized and characterized. The studies on their structure–property relationship show that the different configurations have a serious effect on the photoluminescence and electroluminescence performance according to the change in singlet–triplet splitting energy (ΔEST) and excited state geometry. This indicates that a better configuration design can reduce internal conversion and improve triplet exciton utilization of TADF materials. Importantly, OLEDs based on 2 exhibited a maximum external quantum efficiency of 8.9%, which is higher than the theoretical efficiency of the OLEDs based on conventional fluorescent materials.

New isomers of phosphole heteroacenes 2-DIPO and 3-DIPO, in which indoles were fused with phospholes in different manners, have been synthesized. It is found that 2-DIPO containing the 5,6-dihydrophospholo[3,2-b:4,5-b′]diindole skeleton is highly emissive in solution and in solid state, but the emission of 3-DIPO bearing 5,7-dihydrophospholo[2,3-b:5,4-b′]diindole is weak because the emission of 2-DIPO and 3-DIPO is originated from π*–π and π*–n transitions, respectively. The OLED using 2-DIPO as emitter exhibits better performance than that based on 3-DIPO on account of the poor emission of 3-DIPO. It is interesting that the filter paper strip containing 2-DIPO could detect gaseous strong acid by naked eye. For example, the emitting color of the test paper changes from green to yellow upon exposure to HCl vapor, and can recover upon exposure to gaseous NH3. This is the first example of a fluorescence sensor probe based on phosphole to detect acid vapors. However, acid cannot induce the change of the emission for 3-DIPO due to the steric effect of neighboring groups of N–CH3 and benzene around PO to prevent the formation of H-bonding between acid and PO in 3-DIPO.

Organic materials with aggregation‐induced delayed fluorescence (AIDF) have exhibited impressive merits for improving electroluminescence efficiency and decreasing efficiency roll‐off of nondoped organic light‐emitting diodes (OLEDs). However, the lack of comprehensive insights into the underlying mechanism may impede further development and application of AIDF materials. Herein, AIDF materials consisting of benzoyl serving as an electron acceptor, and phenoxazine and fluorene derivatives as electron donors are reported. They display greatly enhanced fluorescence with increased delayed component upon aggregate formation. Experimental and theoretical investigations reveal that this AIDF phenomenon can be rationally ascribed to the suppression of internal conversion and the promotion of intersystem crossing in solid. Moreover, the theoretical calculations disclose that the efficient solid‐state delayed fluorescence originates from the higher energy electronic excited state (e.g., S2) rather than the lowest energy‐excited state (S1), demonstrating an anti‐Kasha behavior. The excellent AIDF property allows high exciton utilization and thus superb performance of OLEDs using these new materials as light‐emitting layers.

Boron‐containing compounds have attracted considerable attention because of their electron‐accepting properties, and they are widely used in a variety of fields. However, due to the essential requirement to protect the empty pz‐orbital of the boron atom using large steric hindrance or rigid groups, borane derivatives generally show poor solubility and are rarely reported as acceptor units to construct bipolar host materials for phosphorescent organic light‐emitting diodes (PhOLEDs). Here, a combined star‐shaped and asymmetric donor–acceptor molecular design strategy to improve the solubility and fine tune the optical and electronic properties of boron‐containing materials is presented. High thermal stability, solvent solubility, solution processability, and triplet energy are achieved simultaneously. With the thus‐designed boron‐containing bipolar molecules as host materials, the solution‐processed PhOLEDs exhibit high device performances, which are comparable to the vacuum‐processed counterparts, showing high external quantum efficiencies up to 18.5% and 14.5% in blue and white PhOLEDs, respectively. These results demonstrate the great potential of the star‐shaped and symmetry‐breaking borane derivatives in solution‐processable organic optoelectronic devices.

Graphene is a promising candidate for the replacement of the typical transparent electrode indium tin oxide in optoelectronic devices. Currently, the application of polycrystalline graphene films grown by chemical vapor deposition is limited for their low electrical conductivity due to the poor transfer technique. In this work, we developed a new method of preparing tri-layer graphene films with chemical modification and explored the influence of doping and patterning process on the performance of the graphene films as transparent electrodes. In order to demonstrate the application of the tri-layer graphene films in optoelectronics, we fabricated the organic light-emitting diodes (OLEDs) based on them and found that plasma etching is feasible with certain influence on the quality of the graphene films and the performance of the OLEDs.

This paper reports the latest technological advances made by the Industrial Technology Research Institute (ITRI) in flexible displays, especially the flexible substrate, thin-film transistor (TFT) backplane, and active matrix organic light-emitting diode display. Using the leading cholesteric liquid crystal technology of ITRI, we develop a rewritable, environmentally friendly thermal printable e-paper. The epaper, devised to reduce traditional paper consumption, achieves a high resolution of 300 dpi with a memory function. In addition, we report on the ITRI's initial success in demonstrating a complete R2R process for multisensing touch panels on 100-μm thick flexible glass substrates provided by Corning.