Efficient Deep-blue Emission Research Articles

Efficient Deep-Blue Light-Emitting Diodes from Highly Luminescent Eu2+-Doped Alkali Metal Halide Nanocrystals via Lattice Field Modulation.

Lead-halide perovskite nanocrystals (NCs) are promising for fabricating deep-blue (<460 nm) light-emitting diodes (LEDs), but their development is plagued by low electroluminescent performance and lead toxicity. Herein, the synthesis of 12 kinds of highly luminescent and eco-friendly deep-blue europium (Eu2+)-doped alkali-metal halides (AX:Eu2+; A = Na+, K+, Rb+, Cs+; X = Cl-, Br-, I-) NCs is reported. Through adjustment of the coordination environment, efficient deep-blue emission from Eu-5d → Eu-4f transitions is realized. The representative CsBr:Eu2+ NCs exhibit a high photoluminescence quantum yield of 91.1% at 441 nm with a color coordinate at (0.158, 0.023) matching with the Rec. 2020 blue specification. Electrically driven deep-blue LEDs from CsBr:Eu2+ NCs are demonstrated, achieving a record external quantum efficiency of 3.15% and half-lifetime of ∼1 h, surpassing the reported metal-halide deep-blue NCs-based LEDs. Importantly, large-area LEDs with an emitting area of 12.25 cm2 are realized with uniform emission, representing a milestone toward commercial display applications.

Gallium Sulfide Quantum Dots with Zinc Sulfide and Alumina Shells Showing Efficient Deep Blue Emission.

Solution-processed quantum dot (QD) based blue emitters are of paramount importance in the field of optoelectronics. Despite large research efforts, examples of efficient deep blue/near UV-emitting QDs remain rare due to lack of luminescent wide band gap materials and high defect densities in the existing ones. Here, we introduce a novel type of QDs based on heavy metal free gallium sulfide (Ga2 S3 ) and their core/shell heterostructures Ga2 S3 /ZnS as well as Ga2 S3 /ZnS/Al2 O3 . The photoluminescence (PL) properties of core Ga2 S3 QDs exhibit various decay pathways due to intrinsic defects, resulting in a broad overall PL spectrum. We show that the overgrowth of the Ga2 S3 core QDs with a ZnS shell results in the suppression of the intrinsic defect-mediated states leading to efficient deep-blue emission at 400 nm. Passivation of the core/shell structure with amorphous alumina yields a further enhancement of the PL quantum yield approaching 50 % and leads to an excellent optical and colloidal stability. Finally, we develop a strategy for the aqueous phase transfer of the obtained QDs retaining 80 % of the initial fluorescence intensity.

Intrinsically Stretchable And Efficient Fully Π-Conjugated Polymer via Internal Plasticization for Flexible Deep-blue Polymer Light-emitting Diodes with CIEy = 0.08.

Intrinsically stretchable polymeric semiconductors are essential to flexible polymer light-emitting diodes (PLEDs) owing to their excellent strain tolerance capacity under long-time deformation operation. Obtaining intrinsic stretchability, robust emission properties, and excellent charge-transport behavior simultaneously from fully π-conjugated polymers (FCPs) is difficult, particularly for applications in deep-blue PLEDs. Herein, wepropose an internal plasticization strategy to introduce a phenyl-ester plasticizer into polyfluorenes (PF-MC4, PF-MC6, and PF-MC8) for narrowband deep-blue flexible PLEDs. Compared with controlled poly[4-(octyloxy)-9,9-diphenylfluoren-2,7-diyl]-co-[5-(octyloxy)-9,9-diphenylfluoren-2,7-diyl] (PODPFs) (2.5%), the freestanding PF-MC8 thin film shows a fracture strain of > 25%. The three stretchable films exhibit stable and efficient deep-blue emission (PLQY > 50%) because of the encapsulation of π-conjugated backbone via pendant phenyl-ester plasticizers. The PF-MC8-based PLEDs show deep-blue emission, which corresponds to CIE and EQE values of (0.16, 0.10) and 1.06%, respectively. Finally, the narrowband deep-blue electroluminescence (FWHM of ∼25nm; CIE coordinates: (0.15, 0.08)) and performance of the transferred PLEDs based on the PF-MC8 stretchable film are independent of the tensile ratio (up to 45%); however, they show a maximum brightness of 1976cd m-2 at a ratio of 35%. Therefore, internal plasticization is a promising approach for designing intrinsically stretchable FCPs for flexible electronics. This article is protected by copyright. All rights reserved.

Design efficient energy transfer Ca2Al2SiO7: Bi3+, Eu3+ phosphors by cationic substitution for full-spectrum W-LED lighting

High lighting quality has become essential in indoor lighting with the continuous technological innovations in the illumination field. The existing mainstream white light implementation cannot completely cover the entire visible light area, whether it is a combination of a blue chip and YAG: Ce3+ (red gap and deep-blue gap) or a combination of an ultraviolet chip and three-color phosphor (cyan gap and deep-blue gap. This study uses Bi3+ as the luminescence center to obtain an efficient deep-blue emission phosphor through local lattice control (Internal Quantum Efficiency = 65%). Subsequently, a Bi3+-Eu3+ energy transfer system with a transfer efficiency of 97.15% was designed to obtain a double emission of deep-blue and red in Ca2Al2SiO7: 0.06Bi3+, 0.04Eu3+ (Internal Quantum Efficiency = 81%). The energy transfer between Bi3+-Eu3+ increases the emission integration intensity to 149% compared to single-doped Eu3+, and the CASO: 0.06Bi3+, 0.04Eu3+ thermal quenching resistance is excellent (3.8% integral strength loss at 425 K). Finally, 395 nm and 310 nm phosphor conversion (pc) W-LED devices with color rendering indexes of 84.2 and 91.6 were prepared by combining CASO: 0.06Bi3+, 0.04Eu3+ and commercially available phosphors, respectively. This result shows that these phosphors can be applied in full-spectrum white illumination.

Fluorene pendant-functionalization of poly(N-vinylcarbazole) as deep-blue fluorescent and host materials for polymer light-emitting diodes

π-Electron coupling of pendant conjugated segment in π-stacked semiconducting polymers always causes the formation of defect trapped sites and further quenched high-band excitons, which is harmful to the performance and stability of deep-blue polymer light-emitting diodes (PLEDs). Herein, considerate of “defect” carbazole (Cz) electromers in poly(N-vinylcarbazole) (PVK), a series of fluorene units are introduced into pendant segments (PVCz-DMeF, PVCz-FMeNPh and PVCz-DFMeNPh) to suppress the strong π-electron coupling of pendant Cz units and enhance radiative transition toward fabricating sable PLEDs. Compared to PVCz-FMeNPh and PVCz-DFMeNPh, PVCz-DMeF spin-coated films show a relatively efficient deep-blue emission, completely similar to its single pendant chromophore, confirmed an extremely weak charge-transfer and electron coupling between adjacent pendant segments. Therefore, PLEDs based on PVCz-DMeF present stable and deep-blue emission with a high color purity (0.17, 0.08), associated with extremely weak defect emission at 600∼700 nm (induced by carbazole electromers). Finally, PLEDs based on PVCz-DMeF/F8BT blended films (1:1) also present the high maximum luminance (Lmax) of 6261 cd/m2 and current efficiency (CEmax) of 2.03 cd/A, confirmed slightly trapped sites formation. Therefore, precisely control the arrangement and packing model of pendant units in π-stacked polymer is an essential prerequisite for building efficient and stable emitter for optoelectronic devices.

Replacing cesium with formamidinium cation in colloidal perovskite nanoplatelets: Synthetic alloying and post-synthetic cation exchange towards efficient blue emission

Blue-emitting perovskite materials have attracted remarkable attention in recent years owing to their potential in full-color display and lighting applications. Two-dimensional (2D) perovskite nanoplatelets (NPls) are considered as competitive blue emitters due to high carrier recombination probability and good spectrum stability compared with their mixed-halide counterparts. However, the 2D nature and high defect density of perovskite NPls generally result in nonradiative carrier recombination, making it problematic for achieving efficient blue emission. Herein, we reported a novel way to enhance the blue emission efficiency of perovskite NPls. We found that by using formamidinium cation (FA+) to replace the cesium cation (Cs+) during NPls synthesis, the photoluminescence (PL) of the NPls can be significantly enhanced. The PL quantum yield (PLQY) of NPls exhibited a monoclinic rising tendency with increased FA+ content, and the FAPbBr3 NPls finally show efficient deep blue emission at 433 nm with PLQY up to 70% as well as narrow emission bandwidth of only 12 nm. We further demonstrated that efficient blue emission can be realized not only by FA+ alloying but also by post-synthetic treatment of the as-synthesized CsPbBr3 NPls using FA+, where the FA+ was capable to replace the Cs+ in perovskite NPls through cation exchange. Resultantly, PLQY as high as 90% was achieved at a pure blue wavelength of 457 nm. Our work provides a promising strategy for achieving efficient and color-pure blue-emitting perovskite materials, which could potentially further promote their light-emitting applications.

Improving the Intrinsic Stretchability of Fully Conjugated Polymer for Deep-Blue Polymer Light-Emitting Diodes with a Narrow Band Emission: Benefits of Self-Toughness Effect.

It is challenging to construct the intrinsically stretchable active layer of rigid conjugated polymers (CPs) toward flexible deep-blue light-emitting diodes (FLEDs). Inspired by the self-toughness effect, sacrificial hydrogen bonding (H-bonding) and a cross-linked network synergistically enabled polydiarylfluorene (PFs-NH) films to present efficient deep-blue emission and excellent intrinsic stretchability. In particular, a cross-linked network structure presenting viscoelasticity behaviors, which was successfully inherited into postprocessed films with interchain interpenetration and a crystallinity domain and behaved as energy absorption and dissipation centers, was induced by the interchain H-bonding interaction in toluene (Tol) precursor solutions where the storage moduli (G') gradually exceeded the loss moduli (G″). Subsequently, intrinsic stretchable films with a tensile rate of 30% were prepared from Tol solutions, different from the brittle films from polar solvents. Eventually, narrow band, deep-blue PLEDs showed a maximum EQE of 1.28% and a full width half-maximum (fwhm) of 28 nm. Therefore, the self-toughness effect induced by hierarchical structures will be feasible to obtain high-performance FLEDs.

Efficient deep blue emission by 4-styrylbenzonitrile derivatives in solid state: Synthesis, aggregation induced emission characteristics and crystal structures

Organic fluorescent molecules with π-conjugated system have shown great importance in numerous applications including bioimaging and optoelectronics. Planar aggregation-induced emissive (AIE) organic compounds with efficient solid-state luminescence are rarely developed and urgently needed in various applications. In this work, highly planar 4-styrylbenzonitrile derivatives have been synthesized. Most of these compounds show strong AIE properties with hundred-fold fluorescent enhancement. Moreover, these molecules are deep blue emissive in solid state, exhibiting good to excellent fluorescence quantum efficiency. The single crystal analysis shows that adjacent molecules could form special J-type aggregation. The intramolecular rotations are efficiently restricted by various noncovalent interactions. These molecular arrangements could be essential for the observed strong emission in aggregated and solid state. This work has paved a new path to efficient AIE-active organic emitters with highly planar conformations from 4-styrylbenzonitrile structure.

Intrinsically Stretchable and Stable Ultra‐Deep‐Blue Fluorene‐Based Polymer with a High Emission Efficiency of ≈90% for Polymer Light‐Emitting Devices with a CIEy = 0.06

AbstractThe manufacture of robust ultra‐deep‐blue polymer with an intrinsic stretchability is an extreme challenge toward fabricating flexible light‐emitting optoelectronic devices. As a key precondition for the realization of the intrinsically stretchable behavior, easily interchain slippages also cause the formation of intermolecular excited states, which is negative to the color purity and the emission efficiency of blue‐emitting film and devices. Herein, a series of π‐interrupted‐conjugated alternating polymers with a robust ultra‐deep‐blue emission and intrinsically stretchable properties are demonstrated. Interestingly, the model polymers (P4, P6, and P8) present stable ultra‐deep‐blue emission with an extremely high efficiency of ≈90% and a Commission internationale de l'éclairage (CIE) coordinates of (0.15, 0.06) in solid‐state, attributed to the excellent singlet excitonic behavior without any obvious polaron formation. More importantly, significantly different to rigid π‐conjugated polymers, the model P8 film displays an efficient deep blue emission even under a tensile rate of ≈15%, associated with the densely interchain entanglement and interpenetration. Finally, preliminary P8‐based polymer light‐emitting diodes also show a stable ultra‐deep‐blue emission with a CIE of (0.15, 0.06). All results above confirm the effectiveness of the π‐interrupted‐conjugated strategy to construct a robust deep‐blue polymer with an excellent intrinsic stretchability, which is a great potential for applying in flexible light‐emitting devices.

Constructing deep-blue bis-tridentate Ir(iii) phosphors with fluorene-based dianionic chelates

Novel fluorene-based bis-tridentate Ir(iii) phosphors are capable of exhibiting both improved stability and efficient deep-blue emission in solution.

In Situ-Fabricated Perovskite Nanocrystals for Deep-Blue Light-Emitting Diodes.

Efficient and stable deep-blue emission from perovskite light-emitting diodes (LEDs) is required for their application in lighting and displays. However, this is difficult to achieve due to the phase segregation issue of mixed halide perovskites and the challenge of synthesizing high-quality single-halide deep-blue perovskite nanocrystals through a traditional method. Here, we show that an antisolvent treatment can facilitate the in situ formation of perovskite nanocrystals using a facile spin-coating method. We find that the dropping time of the antisolvent can significantly affect the constitution of nanocrystal perovskite films. With a delay in the start time of the antisolvent treatment, small single-halide perovskite nanocrystals can be achieved, exhibiting efficient deep-blue emission. The LED device shows a stable electroluminescence (EL) peak at 465 nm, with a peak external quantum efficiency and a peak current efficiency of 2.4% and 2.5 cd A-1, respectively. This work provides a facile approach to changing the size of perovskite nanocrystals, thus effectively tuning their EL emission spectra.

Anthracene derivatives as highly efficient deep-blue emitters with extremely low driving voltages, Von ≤2.7 V

In this work, we report a feasible and versatile method to synthesize bis(N1, N1, N3, N3-tetraphenylbenzene-1,3-diamine) (TPDA) group as a donor group for OLEDs. A series of novel tetraphenyl-diamine-phenyl end-capped anthracene derivatives, 5-(anthracene-9-yl)-N1, N1, N3, N3-tetraphenylbenzene-1,3-diamine (TPDAAn), N1, N1, N3, N3-tetraphenyl-5-(10-phenylanthracen-9-yl)benzene-1,3-diamine (TPDAPhAn), 5,5'-(anthracene-9,10-diyl)bis(N1, N1, N3, N3-tetraphenylbenzene-1,3-diamine) (dTPDAAn) were synthesized through a facile route. The doped devices based on TPDAAn, TPDAPhAn and dTPDAAn exhibit high EQE up to 4.01% and deep-blue emission with CIE coordinates of (0.15, 0.05), which fully meet the requirements of European Broadcasting Union (EBU) standard blue CIE coordinates of (0.15, 0.06). The non-doped devices based on TPDAAn and TPDAPhAn also display efficient deep-blue emission with CIEy coordinates of 0.08, matching very well with the National Television System Committee (NTSC) standard blue CIEy coordinate for display applications. More importantly, the non-doped devices show extremely low driving voltages (Von ≤ 2.7 V), making them one of the lowest driving voltage devices with CIEy ≤ 0.8.

Highly efficient deep-blue light-emitting material based on V-Shaped donor-acceptor triphenylamine-phenanthro[9,10-d]imidazole molecule

Based on novel phenanthro[9,10-d]imidazole (PI) chromophore, three deep-blue luminescent donor-acceptor molecules with different molecular configurations at the triphenylamine (TPA) core were designed and synthesized, the linear TPA-1PI, the V-shaped TPA-2PI and the star-shaped TPA-3PI. All three molecules displayed the hybridized local and charge-transfer (HLCT) excited state character, and highly efficient deep blue emissions were observed in their solution state, but only those of linear TPA-1PI and V-shaped TPA-2PI molecule were maintained in the solid state. Meanwhile, the V-shaped TPA-2PI and star-shaped TPA-3PI showed the much better thermal properties. Thus the molecular configurations of HLCT materials significantly influence their solid-state, and the V-shaped TPA-2PI molecule was highlighted because of its both deep-blue emission and good thermal stability. A double-layer device by using TPA-2PI as the emitter showed a highly efficient deep-blue electroluminescence with a very good CIE coordinate of (0.14, 0.08) and high current efficiency of 2.7 cd A−1, which suggest that it might be a promising candidate for emission-layer materials for high-performance deep-blue OLEDs.

Phase transition and energy transfer of lead-free Cs2SnCl6 perovskite nanocrystals by controlling the precursors and doping manganese ions

Perovskite quantum dots (QDs), such as all-inorganic CsPbX3 (X = Cl, Br, and I), are novel fluorescent semiconductor nanocrystals (NCs) that have attracted tremendous attention due to their excellent optical properties and great applications (e.g. display backlights, light-emitting diodes, and photodetectors). The instability and toxicity of lead-based perovskite QDs, however, are intrinsic defects that obstruct their application and commercialization. Poison is released from the lead of the unstable CsPbX3 NCs, which are generally ascribed to the labile surface, ionic character, and metastable structure. In this work, lead-free Cs2SnCl6 perovskite NCs are successfully synthesized via hot injection. Particularly, by controlling the different precursor ratios, phase transition (CsCl to Cs2SnCl6) was clearly observed from X-ray diffraction (XRD) measurements. The Cs2SnCl6 NCs exhibited a highly efficient deep-blue emission at 425 nm, with a 55 nm Stokes shift and an 84 nm full width at half maximum (FWHM). After doping Mn ions, the preferred formation of CsSnCl3:Mn2+ with double-wavelength emission was demonstrated based on the XRD and photoluminescence spectra. The study showed that doping synthesis should be widely used in lead-free perovskite NCs as an important strategy for next-generation solid-state lighting.

A bipolar deep blue-emitting fluorescent material based on imidazole and triphenylamine for efficient non-doped OLEDs

A bipolar deep blue-emitting fluorescent material, 1-(4-tert-butyl phenyl)-2-[4-(N,N- diphenyl)phenyl]-4,5-diphenyl-1H-imidazole (TPA-PIM) has been designed and synthesized for efficient blue organic light-emitting diodes (OLEDs). The photophysical, thermal and electrochemical properties of TPA-PIM are investigated. TPA-PIM possesses high thermal stabilities with decomposition temperature of 396 °C and shows a strong deep-blue emission at 407 nm in N, N-dimethylformamide (DMF) solution. Single-carrier devices are fabricated to show that TPA-PIM has good bipolar characteristics. The non-doped fluorescent OLEDs using TPA-PIM as emitter exhibited stable and efficient deep-blue emissions with the CIE coordinates of (0.16, 0.09), the maximum luminance of 1392 cd m−2 and the maximum current efficiency of 2.60 cd A−1.

Simple cuprous iodide complex‐based crystals with deep blue emission and high photoluminescence quantum yield up to 100%

Luminescent cuprous complexes have attracted much attention due to their low cost, rich photophysical properties, and hence extensive applications in various fields. In this work, we report the synthesis, structure and photophysical properties of a simple and highly efficient deep blue emission cuprous iodide complex, namely CuI (PPh3)2(t‐BuPy), where PPh3 and t‐BuPy stand for triphenylphosphine and 4‐tert‐butylpyridine, respectively. The complex was synthesized with a one‐pot method, and showed a super high photoluminescence quantum yield up to 100% and a maximum emission wavelength at 454 nm in crystals at room temperature. Based on density functional theory calculation, the emission likely comes from iodide to 4‐tert‐butylpyridine charge transfer and some copper to 4‐tert‐butylpyridine charge transfer excited states. Two reference complexes, CuI (PPh3)2(IQu) (IQu = isoquinoline) and Cu2I2(PPh3)2(t‐BuPy)2, were also synthesized, and the photophysical properties of the three compounds in various forms such as crystalline powder, thin film and solution at both room temperature and 77 K were studied for comparison. These results give clues on how the N‐heteroaromatic ligand (4‐tert‐butylpyridine vs. isoquinoline), coordinating style (mononuclear vs. binuclear), sample form (crystalline powder vs. thin film vs. solution) and temperature (room temperature vs. 77 K) affect the photophysical properties of luminescent cuprous iodide complex.

Highly Efficient Organic Blue Electroluminescent Materials and Devices with Mesoscopic Structures.

Due to the difficulty in achieving high efficiency and high color purity simultaneously, blue emission is the limiting factor for the performance and stability of OLEDs. Since 2003, we have been working on organic light-emitting diodes (OLEDs), especially on blue light. After a series of molecular designs, novel strategies have been proposed from different aspects. At first, highly efficient deep blue emission could be achieved through molecular design with highly twisted structure to suppress fluorescence quenching and redshift. Deep blue emitters with high efficiency in solid state, a twisted structure with aggregation induced emission (AIE) characteristics was incorporated to inhibit molecular aggregation, and triplet-triplet fusion (TTF) and hybridized localized charge transfer (HLCT) were adopted to increase the ratio of triplet exciton used. Secondly, a highly efficient blue OLED could be achieved through improving charge transport. New electron transport materials (ETMs) with wide band gap were developed to control charge transport balance in devices. Thirdly, a highly efficient deep blue emission could be achieved through a mesoscopic structure of out-coupling layer. A mesoscopic photonic structured organic thin film was fabricated on the top of metal electrode by self-aggregation in order to improve the light out-coupling efficiency.

Enabling a 6.5% External Quantum Efficiency Deep-Blue Organic Light-Emitting Diode with a Solution-Processable Carbazole-Based Emitter

Highly efficient deep-blue emission is crucial to realize energy-efficient and high-quality display and solid-state lighting applications. A solution-processable deep-blue emitter is essential for producing cost-effective large-area devices via roll-to-roll fabrication. Here, we demonstrate a highly efficient solution-processable deep-blue organic light-emitting diode by utilizing a carbazole-based fluorescent emitter 6-((9,9-dibutyl-7-((7-cyano-9-(2-ethylhexyl)-9H-carbazol-2-yl)ethynyl)-9H-fluoren-2-yl)ethynyl)-9-(2-ethylhexyl)-9H-carbazole-2-carbonitrile (JV55). The resultant device showed a maximum external quantum efficiency (EQE) of 6.5% and an EQE of 5.5% at 100 cd/m2 with CIE coordinates of (0.16, 0.06). The optimized device showed a maximum EQE of 6.5%. Additionally, the deep-blue emission also realized a 101% color saturation according to the NTSC standard. The high efficiency may be attributed to engineering appropriate device architecture and enabling balanced carrier injection, effective host-...

Manipulating the Electronic Excited State Energies of Pyrimidine-Based Thermally Activated Delayed Fluorescence Emitters To Realize Efficient Deep-Blue Emission.

The development of efficient and robust deep-blue emitters is one of the key issues in organic light-emitting devices (OLEDs) for environmentally friendly, large-area displays or general lighting. As a promising technology that realizes 100% conversion from electrons to photons, thermally activated delayed fluorescence (TADF) emitters have attracted considerable attention. However, only a handful of examples of deep-blue TADF emitters have been reported to date, and the emitters generally show large efficiency roll-off at practical luminance over several hundreds to thousands of cd m-2, most likely because of the long delayed fluorescent lifetime (τd). To overcome this problem, we molecularly manipulated the electronic excited state energies of pyrimidine-based TADF emitters to realize deep-blue emission and reduced τd. We then systematically investigated the relationships among the chemical structure, properties, and device performances. The resultant novel pyrimidine emitters, called Ac-XMHPMs (X = 1, 2, and 3), contain different numbers of bulky methyl substituents at acceptor moieties, increasing the excited singlet (ES) and triplet state (ET) energies. Among them, Ac-3MHPM, with a high ET of 2.95 eV, exhibited a high external quantum efficiency (ηext,max) of 18% and an ηext of 10% at 100 cd m-2 with Commission Internationale de l'Eclairage chromaticity coordinates of (0.16, 0.15). These efficiencies are among the highest values to date for deep-blue TADF OLEDs. Our molecular design strategy provides fundamental guidance to design novel deep-blue TADF emitters.

Highly twisted bipolar emitter for efficient nondoped deep-blue electroluminescence

Three novel bipolar deep-blue emitters, 1-(4-(tert-butyl)phenyl)-2-(4-(9,9-diphenylacridin-10(9H)-yl)phenyl)-1H-phenanthro[9,10-d]imidazole (DPACTPI), 1-(4-(tert-butyl)phenyl)-2-(4′-(9,9-diphenylacridin-10(9H)-yl)-[1,1′-biphenyl]-4-yl)-1H-phenanthro[9,10-d]imidazole (DPACPhTPI) and 2-(4-(9,9-diphenylacridin-10(9H)-yl)phenyl)-1-(4-(trifluoromethyl)phenyl)-1H-phenanthro[9,10-d]imidazole (DPACFPPI), employing the donor 9,9-diphenyl-9,10-dihydroacridine (DPAC) and the acceptor, phenanthroimidazole, were designed and synthesized. The highly twisted conformations between DAPC and phenanthroimidazole in the molecules efficiently interrupt molecular π-conjugation and inhibit π-π intermolecular interactions, resulting in good thermal stability and efficient deep-blue emission. The three phenanthroimidazole derivatives in non-doped OLEDs exhibited deep-blue emission. In particular, DPACPhTPI-based nondoped device showed an excellent performance with maximum external quantum efficiency (EQE) of 3.50%, maximum current efficiency (CE) of 1.38 cd/A, maximum power efficiency (PE) of 1.40 lm/W and CIE coordinate of (0.156, 0.047), which is among the best results for OLEDs with a similar color. The high radiative exciton utilization could be resulted from hybridized local and charge transfer (HLCT).