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Four emitters based on the naphthyridine acceptor moiety and various donor units exhibiting thermally activated delayed fluorescence (TADF) were designed and synthesized. The emitters exhibited excellent TADF properties with a small ΔE ST and a high photoluminescence quantum yield. A green TADF organic light-emitting diode based on 10-(4-(1,8-naphthyridin-2-yl)phenyl)-10H-phenothiazine exhibited a maximum external quantum efficiency of 16.4% with Commission Internationale de L'éclairage coordinates of (0.368, 0.569) as well as a high current and power efficiency of 58.6 cd/A and 57.1 lm/W, respectively. The supreme power efficiency is a record-high value among the reported values of devices with naphthyridine-based emitters. This results from its high photoluminescence quantum yield, efficient TADF, and horizontal molecular orientation. The molecular orientations of the films of the host and the host doped with the naphthyridine emitter were explored by angle-dependent photoluminescence and grazing-incidence small-angle X-ray scattering (GIWAXS). The orientation order parameters (ΘADPL) were found to be 0.37, 0.45, 0.62, and 0.74 for the naphthyridine dopants with dimethylacridan, carbazole, phenoxazine, and phenothiazine donor moieties, respectively. These results were also proven by GIWAXS measurement. The derivative of naphthyridine and phenothiazine was shown to be more flexible to align with the host and to show the favorable horizontal molecular orientation and crystalline domain size, benefiting the outcoupling efficiency and contributing to the device efficiency.

Four bipolar molecules, named 1-, 2-, 3-, and 4-3cbzBIZ, composed of tricarbazole (3cbz) substituted benzimidazole, were synthesized and characterized.

In this study, we develop a steady state and time-dependent exciton diffusion model including singlet and triplet excitons coupled with a modified Poisson and drift-diffusion solver to explain the mechanism of hyper triplet-triplet fusion (TTF) organic light-emitting diodes (OLEDs). Using this modified simulator, we demonstrate various characteristics of OLEDs, including the J-V curve, internal quantum efficiency, transient spectrum, and electric profile. This solver can also be used to explain the mechanism of hyper-TTF-OLEDs and analyze the loss from different exciton mechanisms. Furthermore, we perform additional optimization of hyper-TTF-OLEDs that increases the internal quantum efficiency by approximately 33% (from 29% to 40%).

Near-infrared emission was achieved via the intermolecular through-space electronic coupling and intramolecular charge transfer.

A novel bis-4Ph-substituted 9,10-dipehnylanthracene deep blue [1931 CIE (0.15, 0.08)] fluorescent compound, AnB4Ph, has been synthesized and characterized for organic light-emitting diode (OLED) applications. Our experimental study of AnB4Ph excludes the possibility of triplet-triplet annihilation, hybridized local and charge transfer, or thermally activated delayed fluorescent characteristics of the material. Since the solid-state photoluminescence quantum yield of AnB4Ph was determined to be 48%, assuming a 100% for the charge recombination efficiency, the light outcoupling efficiency (ηout) of an AnB4Ph non-doped OLED achieving an external quantum efficiency (EQE) of 5.3% is at least 44%, which is more than twofold higher than 20% for conventional OLEDs. Both grazing incidence wide-angle X-ray scattering (GIWAXS) and angle-dependent photoluminescence (ADPL) measurements reveal AnB4Ph having a high value of order parameter (SGIWAXS) of 0.61 for a ππ stacking along the normal direction and an orientation order parameter (SADPL) for a horizontal emitting dipole moment of -0.50 or Θ (horizontal-dipole ratios) of 100%, respectively. Otherwise, a refractive index (n) measurement provides a n = 1.80 for AnB4Ph thin films. Based on ηout = 1.2 × n-2, the calculated ηout is 37%, which is also in accordance with the results of GIWAXS and ADPL. We have also fabricated the classical fluorescent DPAVBi-doped AnB4Ph OLEDs, which display a true blue [1931 CIE (0.15 and 0.16)] electroluminescence with a high efficiency (EQE = 6.9%), surpassing the conventional ∼5% EQE. Based on an ηout of 42% for DPAVBi-doped AnB4Ph OLEDs, our studies suggest that the extremely horizontally aligned AnB4Ph host material exerts the same horizontal alignment on the DPAVBi dopant molecules.

To fulfill the requests of highly vivid colors in displays and customized spectra in solid-state lighting (SSL), a cost-effective approach to create color-tunable downconverters with narrow emission spectra is in demand. In this regard, perovskite nanocrystal downconverters have aroused great interest due to their narrow-band, tunable emission and easy manufacturing process. However, environmental instability is still the major concern of their commercialization, especially for red-emitting downconverters. Herein, built upon the previous successful development of a swelling–deswelling microencapsulation (SDM) method, we report a deep-dyeing strategy that can directly convert commercial solvent-resistant polymer matrices (e.g. polyethylene terephthalate (PET)) into polymer-protected deep-dyed perovskite polymer composites (DDPPCs) with outstanding color tunability, excellent pure color, and superior environmental stability. The MAPbBr3-based DDPPCs manifest a high photoluminescent quantum yield of 77.9%. Moreover, they survived in water for over 3 years without visible degradation, their photoluminescence (PL) is reversible under a 140 °C heating–cooling cycle, and they maintained 87.6% of the original PL intensity after 10 hours of continuous blue laser excitation. More importantly, the as-synthesized CsPbBr0.75I2.25-based red DDPPCs also exhibit excellent water-, thermal-, and photo-stability. The deep-dyeing process is expected to achieve highly stable PPCs for next-generation displays, SSL or other applications.

35Cbz4BzCN, a novel universal host with a long triplet lifetime, has been developed. The triplet excitons in 35Cbz4BzCN can be effectively harvested by phosphorescence and thermally activated delayed fluorescence emitters. In the 4CzIPN doped device, the best performance of a maximum current efficiency of 111.8 cd A−1, power efficiency of 86.8 lm W−1, and external quantum efficiency of 31.7% with a small efficiency roll-off of 103 cd A−1 at 1000 cd m−2 has been achieved. 35Cbz4BzCN is also compatible with FIrpic to give sky-blue emission up to 46.3 cd A−1 and with TXO-TPA to give orange-red emission up to 60.6 cd A−1 efficiency.

Triplet is like a double-edged knife, that can degrade or benefit the electroluminescence performances of organic light-emitting diodes (OLEDs), especially for blue light. Therefore, efficient triplet harvesting for triplet-triplet fusion (TTF) fluorescence emission is essential to achieving high-efficiency blue TTF-OLEDs, which are known for their excellent reliability. This study presents a hyper-TTF mechanism for maximizing triplet exciton usage and avoiding triplet-polaron quenching to generate more photons through Dexter energy transfer (DET) and TTF processes. Specially, a triplet tank layer (TTL) was introduced adjacent to the TTF emitting layer (EML). Efficient carrier recombination and triplet generation are confined to the TTL of the device. Most triplets were observed to undergo DET from the TTL to the TTF EML; they subsequently became singlets exhibiting delayed fluorescence. Furthermore, the triplet-polaron quenching is suppressed by inhibiting hole into the TTF EML. A record-high TTF-OLED efficiency was achieved with an external quantum efficiency of 15.4%.

Efficient deep-blue thermally activated delayed fluorescence with emission maximum at 425 nm and a photoluminescence quantum yield of 84% were observed for the synthesised di-tert-butyl-dimethylacridinyl disubstituted oxygafluorene dispersed under a nitrogen atmosphere in an inert polymer. Its TADF intensity decreased by 14 times when the sample was placed under an oxygen environment showing its potential for optical sensing of oxygen. The optical sensor demonstrated oxygen sensitivity of up to ca. 30 000 ppm with a Stern–Volmer constant KSV of 5.26 × 10−5 ppm−1. Electroluminescence spectrum with a peak wavelength at 446 nm and full width at half maximum of 62 nm was observed using the compound as a thermally activated delay fluorescence emitter in organic light-emitting diodes. Maximum external efficiency of the deep-blue device with CIEy of 0.08 reached 9.9%.

Two bipolar hosts, 8-cbzBIFP and 10-cbzBIFP, both with basic skeletons of orthogonally-connected carbazole and benzimidazo〈1,2-f〉phenanthridine (BIFP) have been prepared. The planar structure of the BIFP moiety governs the molecular stacking in the crystal lattice. Electron transport properties, in comparison to the 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−2, the maximum current efficiency (ηc) of 87.0 cd A−1 and external quantum efficiency (EQE) of 21.1%. Likewise, 8-cbzBIFP shows an Lmax of 58 870 cd m−2, ηc of 77.3 cd A−1 and EQE of 19.1%.

Two new analogues of a popular host material, meta-bis(N-carbazolyl)phenylene (mCP), bearing either methoxy- (mCP-OMe) or tert-butyl (mCP-t-Bu) substituents at C-3 and C-6 positions of carbazole moieties were synthesized and characterized. These materials exhibit higher glass-transition temperatures (79 and 145 °C) than mCP (67 °C). They show reversibility upon electrochemical oxidation while preserving high enough triplet energy levels (2.86 and 2.97 eV). The vacuum-deposited layer of mCP-t-Bu showed hole mobility of 8 × 10−3 cm2V−1s−1 at the electric field of 1.2 × 105 Vcm−1. This value is more than by one order of magnitude higher than that of mCP. The new compounds were tested as hosts for commercial emitters: blue phosphor, bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) (FIrpic), green and blue thermally-activated delayed fluorescence (TADF) emitters 1,2,3,5-tetrakis(9-carbazolyl)-4,6-dicyanobenzene (4CzIPN) and bis[4-(9,9-dimethyl-9,10-dihydroacridin-10-yl)phenyl]sulfone (DMAC-DPS). Blue phosphorescent OLED based on mCP-t-Bu as the host showed up to 22.0% external quantum efficiency. When doping 4CzIPN into mCP-OMe host, a broad emission with peaks at 388, 514, and 572 nm was observed.

Developing a colloidal quantum-dot light-emitting device (QDLED) with high efficiency and good reliability is necessarily preliminary for the next-generation high-quality display application. Most QDLED reports are focused on efficiency improvement, but the device operational lifetime issue is less addressed and also the relevant degradation mechanisms. This study achieved a 1.72 times elongation in the operational lifetime and a 9 times improvement in the efficiency of QDLED by inserting a hole-transporting/electron-blocking poly(9-vinylcarbazole) (PVK) layer, which prevented operational degradation on poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-secbutylphenyl))-diphenylamine)] (TFB) hole-transporting layer and also confined the electron in the QD-emitting layer. Although the TFB/PVK HTL structure is a well-known pair to enhance the device performance, its detailed mechanisms were rarely mentioned, especially for relative operational lifetime issues. Herein, a new insight behind operational lifetime elongation of QDLED is disclosed through various fundamental experiments including steady-state photoluminescence, transient electroluminescence and single-carrier only devices. Evidently, other than QD degradation, this study found that the other crucial factor that decreased the device lifetime was TFB-HTL degradation using steady-state photoluminescence and transient electroluminescence analyses. The PVK electron-only device exhibited a stable voltage value when it was driven by fixed current, which also affirmed that PVK has excellent electron-stability characteristics.

Recently, a new emission mode, triplet-triplet annihilation up conversion (TTAUC), of OLED was proposed with the mechanism as follows: when the carriers recombine at the sensitizer layer with a lower energy bandgap, the generated triplet excitons of sensitizer transfer to the triplet-triplet annihilation (TTA) emitter and emit a higher energy photon. In our experiment, we used tris(8-hydroxyquinolinato)aluminum (Alq3) as sensitizer, 9,10-Bis(2-naphthyl)anthraces (ADN) as TTA emitter and 1,1'-(2,5-Dimethyl-1,4-phenylene)dipyrene (DMPPP) as triplet diffusion singlet blocking (TDSB) layer. To improve the efficiency of TTAUC-OLED, 4,4’ -Bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi), was doped in ADN host. With 6% of DPAVBi doping, no obvious change was observed in electrical characteristics, indicating electron traps from dopant is limited. Maximum EQE achieved EQE= 4.66% in the optimized device.

In this study, we report a bistriazoles derivative to be the wide bandgap host for blue emitters. In particular, this bistriazoles derivative possesses a wide bandgap of 4.0 eV and bipolar carrier transportation behavior. In addition, its bipolar behavior is classified to the rare case of electron-favorable bipolar carrier transportation, which was identified by the time-of-flight measurement and unipolar device. The electron mobility is little faster than hole one, which benefits the adjustment of carrier balance in the emitting layer. Employing to be the host of blue phosphorescent OLED, the device exhibits a high-efficiency performance with a 30.2%EQE.

Although phosphorescent and thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLED) exhibit high efficiency and long lifetime for red and green emission, blue OLED is still a bottleneck. In mass production, triplet-triplet emission (TTA) OLED is the main stream for reasonable lifetime together with limited efficiency. To improve the efficiency of blue TTA-OLED, a bilayer emitting layer (EML) was employed. Compared to single-EML device, external quantum efficiency of the bilayer OLED increased from 9.4% to 13.0%, which mainly resulted from the increase of delayed emission from 15.0% to 37% with enhanced TTA process.

Recently, Quantum-dot light-emitting diode (QLED) has attracted much attention due to narrow electroluminescence (EL) spectra, low driving voltage, tunable emission colors and simple fabrication. In conventional QLED structure, inorganic zinc oxide (ZnO) nanoparticles was usually used as electron transporting layer material by spin-coating. However, defects in solution-processed ZnO film may quench quantum dot (QD) emission and increase the driving voltage. In this study, we fabricated ZnO by sputtering process with the inverted structure. Compared to the QLED with solution-processed ZnO as the ETL, driving voltage of the device with sputtered-ZnO as the ETL significantly decreased from 7.04 V to 2.95 at current density of 20 mA/cm2, while the current efficiency remained at 11.46 and 11.70 cd/A at current density of 80 mA/cm2.

Lots of attentions owing to its superior properties such as narrow electroluminescence (EL) spectra, tunable emission colors, high luminance, and simple fabrication process. Typically, in a QLED, quantum dots (QD) layer is sandwiched by organic materials as hole transporting layer (HTL) and inorganic zinc oxide (ZnO) nanoparticles as electron transporting layer (ETL), respectively. Because the electron mobility of ZnO is typical higher than the hole mobility of organic material, it results in carrier unbalance and reduces the efficiency. Hence, it is important to improve the hole transporting ability to achieve charge balance condition for higher efficiency. In this study, we have fabricated green QLEDs with two different HTL materials. By using HTL with high mobility and suitable energy level, voltage decreased from 11.1 V to 5.8 V at 10 mA/cm2, together with enhancement of current efficiency from 21.8 cd/A to 58.1 cd/A, and external quantum efficiency from 5.94% to 16.0%, corresponding to 2.6-times improvement.

A nanostructured molybdenum trioxide (MoO3) layer was successfully fabricated utilizing various deposition rates, employed as an anodic buffer layer to separate the active layer from a silver anode and modifying the anodic surface to facilitate hole transportation for top-incident organic photovoltaic (TIOPV) devices. The deposition rate and thickness of the MoO3 layer were crucial parameters for determining the surface morphology and work function, and the internal optical field distribution, respectively. These factors affected the performance of the devices in terms of their open-circuit voltage (VOC), short-circuit current density (JSC), and fill factor (FF). The baseline TIOPV device without a buffer layer had a power conversion efficiency (PCE) of only 0.47%. By contrast, with a smooth 20-nm MoO3 buffer layer fabricated using a deposition rate of 1 Å/s (which prevented problems caused by the Ag anode), another fabricated TIOPV device had substantially higher VOC, JSC and FF values, which improved the PCE by a factor of 6.2 to 2.92%. When an additional 5-nm nanostructured MoO3 layer was deposited at a deposition rate of 0.5 Å/s, the most efficient TIOPV device had an even greater PCE, a factor of 7.5 times higher at 3.53%.

A numerical solver based on two-dimensional Poisson and drift-diffusion equations with Gaussian-shaped density of states, the Poole-Frenkel field mobility model, and the Ising model are proposed to analyze carrier transport in the host-guest systems based on organic semiconductors. To investigate the performance of this solver, a series of the electron-only devices and hole-only devices are fabricated with different dopant concentrations. The space-charge-limited current model is applied to the simulation results to calculate the mobility. In addition, experimental results for different host-guest systems are compared to prove the accuracy of the solver. The solver is able to explain the physical mechanisms in different situations. At lower dopant concentrations, the guest states act as traps. Carriers are localized in these guest states, and the carrier mobility decreases dramatically. At the higher dopant concentrations, regions of guest material are able to connect with each other, and carriers have a probability to hop through the guest states. The mobility characteristics gradually approach those of the pure guest material.

A lifting based reversible data hiding is introduced here. The low–high subband is subdivided into little blocks of size (4 × 4), to generate a content dependent watermark. Then the access management is done by permutation of the content dependent watermark by a user-specific covert key. The permuted watermark is employed to modulate the lifting coefficients of the low–high subband. The modulation causes degradation of the visual quality of the host image. That plays an important role in access management through inverse method. Lastly, a low-power ‘very-large-scale-integration’ architectural hardware of this scheme is designed and synthesized on a ‘field programmable gate array’. The experiment is conducted over a variety of benchmark images and the results establish the superiority of the method. It is also observed that in real-time processing, the scheme consumes 63.26% less power than the related implementation found in the literature, for watermarking encoder and decoder at a maximum operating frequency of 130.186 MHz for the processing of (512 × 512) sized images.

Four new donor–acceptor–acceptor (D–A–A) type molecules (DTCPB, DTCTB, DTCPBO, and DTCTBO), wherein benzothiadiazole or benzoxadiazole serves as the central A bridging triarylamine (D) and cyano group (terminal A), have been synthesized and characterized. The intramolecular charge-transfer character renders these molecules with strong visible light absorption and forms antiparallel dimeric crystal packing with evident π–π intermolecular interactions. The characteristics of the vacuum-processed photovoltaic device with a bulk heterojunction active layer employing these molecules as electronic donors combining C70 as electronic acceptor were examined and a clear structure–property–performance relationship was concluded. Among them, the DTCPB-based device delivers the best power conversion efficiency (PCE) up to 6.55% under AM 1.5 G irradiation. The study of PCE dependence on the light intensity indicates the DTCPB-based device exhibits superior exciton dissociation and less propensity of geminated recombina...

Singlet fission of organic molecules has attracted recent attention owing to its potential advantages in organic photovoltaic and electroluminescence applications. Its microscopic mechanism however...

The recent progress of efficiency improvement, emission color tuning, and lifetime elongation of blue organic light-emitting diodes (OLEDs) is reviewed. The latter is one of the most important bottlenecks for OLED development. The current status of blue light-emitting material design with emission mechanisms such as fluorescence (F), phosphorescence (Ph), thermally activated delayed fluorescence (TADF), and hybridized local and charge transfer (HLCT) is introduced in the first part of this review. Compared to red and green devices, the long exciton lifetime of the high energy triplet exciton in a blue OLED is the one of the main issues. To avoid the accumulation of high energy triplet excitons in the emitter for blue OLEDs, assisted triplet–triplet fluorescence (TTF) and Hyperfluorescence™ are employed to harvest the triplet excitons. In the second part of this review, we focus on issues from an application viewpoint: what are the requirements of blue OLEDs for display and lighting technologies in terms of efficiency, color, and lifetime? Key performance metrics of blue OLEDs with different technologies over time are summarized. Independent of technology, the trend is similar: the external quantum efficiency improves for the first stage of research, followed by color tuning, and then finally lifetime elongation. The state-of-the-art device performance of blue OLEDs with various emission mechanisms is illustrated. Although Ph- and TADF-emission based devices show satisfactory efficiency and electroluminescence (EL) spectra, despite having a lower efficiency TTF-emission based devices are the mainstream for real applications due to their relatively long operation lifetime. Blue Ph-OLEDs have the potential for lighting applications with suitable material selection and device design. We collected the published results and tried our best to make a fair comparison of the operation lifetime among different technologies. Finally, we discuss the possible future outlook from different viewpoints including new materials, device designs, and applications of blue OLEDs.

This study reported the effects of electron transport layer (ETL) thickness on light extraction in corrugated organic light-emitting diodes (OLEDs) and each layer in OLEDs exhibited a periodical corrugated structure, which was determined by depositing thin films on a glass substrate with a nanoimprinted blazed grating structure. The insight is that light extraction in corrugated OLEDs significantly depends on the ETL thickness. Varying the ETL thickness changed the distribution of carrier recombination and led to exciton formation and optical interference, thereby resulting in different attribution of optical loss modes in OLEDs, which increased or even decreased light extraction and device efficiency. Trapped light extraction from the surface plasmon polariton (SPP) and waveguide (WG) modes was identified by splitting the light into transverse electric and transverse magnetic emissions. Thus, the contributions from the individual SPP and WG modes to the external quantum efficiency (EQE) were distinctly clarified by comparing the experimental results with the theoretical calculations. At the ETL thickness of 115 nm, the corrugated OLED exhibited a significantly enhanced (1.83-fold) EQE compared to the planar one due to the effective extraction of trapped light from the SPP and WG modes. The EQE was enhanced by 0.5%, wherein 0.39% came from the WG mode and 0.11% came from the SPP mode.

The inclusion of a tetraphenylbenzene (4Ph) unit in thermally activated delayed fluorescence emitters is demonstrated as a novel strategy for greatly enhancing the horizontally oriented alignment of the emitters without shifting the emission spectrum to longer wavelengths. Doping of blue-emitting 4PhOXDDMAC or greenish-blue-emitting 4PhOXDPXZ into o-DiCbzBz host layers yielded much higher degrees of horizontally oriented alignment for the emitter (up to 92%) compared to those when the 4Ph unit was excluded (69 and 75%, respectively). The enhanced alignment results in high outcoupling efficiencies of 24 and 35% in organic light-emitting diodes based on 4PhOXDDMAC and 4PhOXDPXZ, respectively, and boosts the external quantum efficiencies to values (8.8 and 29.2%, respectively) that are higher than what would be expected for randomly oriented emitters (outcoupling efficiency of 20%). These enhancements are achieved while avoiding the redshift that often occurs using the common strategy of increasing molecular length and, thereby, conjugation, to increase orientation.

We present a theoretical investigation of coupling efficiency of a laser diode to a single-mode circular core triangular index fiber coupling via upside-down tapered hemispherical microlens on the tip of the fiber in presence of possible transverse and angular offsets. Using the relevant ABCD matrix formalism for such type of coupler, we prescribe analytical formulations of coupling efficiencies in presence of the said mismatches. Using the prescribed expressions, we evaluate the coupling efficiencies in presence of transverse as well as angular misalignments. The concerned execution involves little computation. The results found will benefit the designers and packagers working in the field of optimum launch optics.

New derivatives of trifluoromethyl benzene and tert-butyl disubstituted acridan or phenothiazine were designed and obtained by single-step synthesis, i.e., by Buchwald-Hartwig cross-coupling reactions of 1,3-dibromo-5-(trifluoromethyl)benzene with 3,7-di-tert-butyldimethylacridan, or 3,7-di-tert-butyl-10H-phenothiazine. The advantages in high thermal and photophysical characteristics were utilized in exciplex emission based OLEDs. In the optimal case, device showed maximum current, power, and external quantum efficiencies of 27.4 cd/A, 28.6 lm/W and 7.6%, respectively. Taking into account that successful employment of acridan or phenothiazine derivatives as donors in exciplex-forming systems remains scarce, the proposed design of donor compounds in this work shows their potential for successful implementation in complex emissive systems of OLEDs.

The efficient conversion of electron-hole (e-h) pairs into triplet excitons is a challenge for blue organic light-emitting diodes (OLEDs) based on triplet–triplet annihilation upconversion (TTAUC). The 25% fraction of e-h pairs that create singlet excitons represents a significant loss channel that can lead to parasitic red-shifted emission. In this study, an intermolecular intersystem crossing that relies on a “dark sensitizer” (DS) layer consisting of tris-(8-hydroxyquinoline)aluminum (Alq3) doped with tris[2-phenylpyridinato-C2,N]Iridium(III) (Ir(ppy)3) is demonstrated to enhance the TTAUC process. Carriers recombination and excitons generation are formed on Alq3 molecules. Alq3 singlet excitons are then quenched by the Ir(ppy)3 triplet state, followed by energy transfer to the Alq3 triplet state. The non-emissive, long-lived Alq3 triplets migrate from the sensitizer layer to an emitter layer where they undergo TTAUC to give blue fluorescence emission. This DS-TTAUC process promises no green emission from the Alq3. The efficiency of a blue OLED utilizing DS-TTAUC was improved by 34.2% compared to a standard TTAUC OLED. In addition, the device exhibited CIE coordinates of (0.15, 0.09). Furthermore, a high photoluminescence quantum yield fluorescence emitter is incorporated to enhance the singlet exciton emission in the emitter layer. A maximum external quantum efficiency of 7.54% can be achieved with recorded-high quantum yield of the TTAUC (ΦTTAUC) = 37.6% in solid state.