FWHM Research Articles

Structural and electrocaloric properties of Yttrium modified Bi0.35Na0.35Sr0.3TiO3 composite

This communication presents the effect of Yttrium and Strontium doping on structural and electrocaloric characteristics of Bismuth Sodium Titanate. Bi0.25Na0.35Sr0.3Y0.1TiO3 electroceramics was synthesized by traditional solid-state mixed-oxide technique. The crystallographic phase formation was confirmed using the X-ray diffraction technique. Rietveld refinement was carried out to extract the unit cell parameters. Average particle size was estimated from the full-width half maxima of the strong XRD peak using Debye-Scherrer’s equation. The temperature dependence of the maximum polarization obtained from P-E loops, the electrocaloric ability of the BNSYT is estimated by calculating the change in the entropy at a field of 6 kV/cm using the standard thermodynamics relation.

Improving the Resolution of Correlation Imaging via the Fluctuation Characteristics

The resolution is an important factor in evaluating image quality. In general, the resolution of correlation imaging is taken to the full width at half maximum (FWHM) of the point spread function (PSF) produced by the second-order correlation function. In this paper, we show that the resolution of correlation imaging can be improved by the fluctuation characteristic of the second-order correlation function. It is demonstrated both experimentally and theoretically that the resolution of the system can be drastically improved. We also prove that the FWHM of the PSF can be narrowed by 2n by extracting the n-order fluctuation information of the second-order correlation function.

Highly uniform microspheres of broadband near-infrared-emitting Ba(Hf1-xCrx)O3 perovskite phosphor

Chromium activated BaHfO3 (BHOC) perovskite phosphor with varying amount of Cr3+ ion (1–10 %) was prepared by hydrothermal synthesis and was characterized systematically using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), positron annhilation lifetime spectroscopy (PALS) and time resolved photoluminescence (TRPL). FESEM show the formation of highly uniform microsphere of BHOC with very smooth surface texture. XPS showed the stabilization of chromium in +3 oxidation states, formation of oxygen vacancies and improved crystallinity in 6 % doped in BHOC sample. Under 500 nm excitation, BHOC perovskite demonstrated a very broad near infrared (NIR) emission band (700–1050 nm) centered at 815 nm with a full width at half-maximum (FWHM) of ∼150 nm and a wide absorption band, suggesting its potential application as NIR phosphor. The fraction of positrons getting trapped in the defects and vacancy clusters decreased with increase in Cr3+ doping and showed minima at 6.0 % doping and this sample also showed highest NIR light emission.

Intense O + E + S-band emission from Pr3+-doped ZnF2-based glasses

Pr3+-doped ZnF2-based glasses were prepared by using a melt-quenching method in dry N2 atmosphere. Under the excitation of a 588 nm light emitting diode (LED), ultrabroadband emissions ranging from 1245 to 1640 nm were obtained from the Pr3+-doped ZnF2-based glasses, which originate from the transitions 1D2→1G4 (producing E + S-band emission) and 1G4→3H5 (producing O-band emission) of Pr3+. The shape of the emission spectra could be tailored by varying the concentration of Pr3+. Emission spectra with the maximum full width at half maximum (FWHM) of 215 nm (1289 nm-1504 nm, covering the O + E + S-band) was obtained in the ZnF2-based glass at a doping concentration of 5000 ppm. The effects of the phonon energy of the matrix on O + E + S-band emission were also investigated. Our results showed that Pr3+-doped ZnF2-based glasses with low phonon energy might be used for constructing O + E + S-band lasers and optical amplifiers.

Technical NEMA NU2-2018 Performance Assessment of Time-of-Flight-Integrated Digital PET-CT System.

Aim The objective of this study includes the NEMA (National Electrical Manufacturer Association) NU2-2018 performance evaluation of the uMIvista PET-CT (positron emission tomography-computed tomography) system. Methods The latest NEMA NU2-2018 guidelines have been followed for the evaluation of performance parameters of this PET-CT scanner: axial, tangential, and radial spatial resolution, sensitivity, counting losses, scatter, randomness, random and counting loss correction, image quality, time and energy resolution, image uniformity, and image registration alignment post installation of country first uMIvista PET-CT. Results The measured NEMA sensitivity of the uMIvista PET scanner was 12.053 cps/kBq. The spatial resolutions of the PET were measured as tangential, radial, and transaxial spatial resolutions at 10 mm, with 3.01 mm, 2.95 mm, and 2.93 mm, respectively; at 100 mm, with 3.17 mm, 3.42 mm, and 3.05 mm, respectively; and at 200 mm, with 3.65 mm, 4.54 mm, and 3.17 mm, respectively, at full-width half-maximum (FWHM); while at full-width tenths-maximum (FWTM), the values at 10 mm were 5.79 mm, 5.57 mm, and 5.69 mm, respectively, and at 100 mm were 5.59 mm, 5.96 mm, and 5.91 mm, respectively. The measured time-of-flight (TOF) timing resolution was 302.294 ps and the measured energy resolution was 11.76% with FWHM and FWTM. Conclusion The NEMA NU2-2018 performances of this TOF-integrated digital PET-CT system are extremely good in all parameters.

Polarization-independent wideband meta-material absorber based on resistor-loaded hexagonal ring resonators

A polarization-independent meta-material-based absorber with wideband response is presented in this study. The proposed absorber’s unit cell consists of a resistance-loaded metallic hexagonal ring and four rectangular metal strips placed inside the hexagonal ring patterned on the upper surface of a dielectric substrate. The absorber exhibits wideband absorption with absorptivity more than 90% in the frequency range 7.14 to 13.68 GHz. The Full-Width Half Maxima (FWHM) of the absorber is 8.8 GHz (5.2–14 GHz). The four-fold symmetrical structure of the absorber confirms polarization-insensitive behaviour. The absorber performance is also validated with fabrication and measurement. There is a fair degree of agreement between simulated and measured results. The novelty of the proposed absorber is having wideband absorption with high packing density due to its hexagonal shape. The metamaterial absorber finds its use in defence-related applications such as radar surveillance, stealth technology, terrestrial communications, and satellite communication.

Design and optimization of dielectric metalens with quasi-periodic arrays

Metalenses have attracted a great deal of research interests due to the property of light controllability. How to enhance the focusing effect of metalens has always been a key problem that many researchers have been working on. In this paper, we propose a novel sub-dimensional resonance-based optimization method for dielectric metalens with golden angle spiral arrays. The waveguiding effect is first applied to the initial design of the quasi-periodic metalens through the defined equivalent period. Then the genetic algorithm is improved for adjusting the sub-dimensional structure of the initial metalens. The optimization results show that the peak intensity of central hot spot increases by 32 % while keeping the full width at half maximum (FWHM) almost unchanged. At the same time, the field intensity of side lobes around the hot spot decreases, which means that a potential way for high-contrast imaging is provided.

Improved heteroepitaxy of κ-Ga2O3 on c-plane sapphire by initial mist flow stabilization during mist chemical vapor deposition

Kappa-phase gallium oxide (κ-Ga2O3) is a metastable gallium oxide polymorph and an ultrawide bandgap semiconductor with potential applications in various electronic and optoelectronic devices. In this study, we present the effect of mist flow stabilization during the initial stages of mist chemical vapor deposition process on the crystal quality of heteroepitaxial thin films of κ-Ga2O3 grown on c-plane sapphire. Two κ-Ga2O3 films were grown using the same growth parameters with the only differing factor being the stabilization of the initial mist flow. Structural and optical properties of the films were characterized. Both processes resulted in epitaxial growth; however, controlling the initial mist flow leads to an improved Ga2O3/Al2O3 interface and superior crystal quality. The film grown with regulated mist flow exhibited an optical bandgap of 4.93 eV, a smooth surface with a root mean square roughness of 1.56 nm and a rocking curve full-width half-maximum value of 0.17°. Also, Ti/Au deposition on κ-Ga2O3 resulted in an interface resembling that of β-Ga2O3 and Ti/Au, explaining previous reports of ohmic behavior between κ-Ga2O3 and Ti/Au contacts.

Ultra-high sensitivity surface plasmon U-channel photonic crystal fiber for hemoglobin sensing

In order to increase the wavelength response range of the U-channel sensor, a numerical study has been conducted and then the sensing structure has been optimized. A sensor in photonic crystal fiber (PCF) is proposed in which a layer of titanium dioxide is coated on the surface of the U-channel and then coated with a gold film. These two different metal films are mainly used to control the Surface plasmon resonance (SPR) peak and the corresponding resonance wavelength, thus changing the sensor performance. Just below the metal layer are two special air holes on either side. They form a leakage window in the center. In the following sections, the effects of these variables on the sensor will be studied in detail by COMSOL. The modal transmission characteristics of this fiber optic sensor are analyzed in this paper. By analyzing the obtained loss spectrum, the energy variation in the surface plasmon polariton (SPP) mode and the influence of the core mode on the sensing performance of the fiber optic sensor presented, the general rule of the optimized PCF-SPR sensor is deduced. In addition, we can make subtle adjustments to the sensor to improve its sensitivity. We found with the refractive index (RI) ranging from 1.26 to 1.42, the maximum wavelength sensitivity is 7500 nm/RIU, which corresponds to a full width at half maximum (FWHM) of 11.83 nm，a figure of merit (FOM) of 634.1 RIU−1. In addition, we also have discussed the sensor and different concentrations of hemoglobin aqueous solution to detect its RI. It is evident from the results that the sensor demonstrates excellent sensitivity and a wide detection range, which is highly desirable for practical diagnostic purposes. The potential of this sensor for clinical trials and its application to medical diagnostics is promising. Compared with complex traditional methods, the PCF has obvious advantages such as clear structure, simple manufacture, high sensitivity and strong environmental adaptability. Moreover, it has the advantage of wide wavelength response range and has a clear development prospect in the field of biochemical sensing. It has foreseeable potential practical value.

A dielectric barrier discharge based low pressure narrow band far UV-C 222 nm excimer lamp and its efficiency analysis

Far UV-C light at wavelength 222 nm is gaining popularity nowadays due to its properties that it cannot penetrate even the outer dead skin of humans and the tear layer of the eyes. This wavelength has been proven to be much safer for human health. In this paper, a dielectric barrier discharge (DBD) based Far UV-C excimer lamp with a very narrow and intense spectrum peaking at a wavelength of 222 nm has been reported. Optimization of high voltage electrodes has been carried out to minimize the lamp heating without using any external cooling. The discharge produced in this configuration is diffused discharge at a low pressure of 140 mbar. Generally, at low pressure, a very wide band of spectra having full-width half maxima (FWHM) of 8–15 nm is obtained. In this case, due to the confined gas gap and bi-polar pulse power arrangements, the spectra obtained are very narrow, having an FWHM of 1.7 nm. Applied voltage, frequency and gas pressure are optimized to get high electrical-to-optical conversion efficiency of the lamp. The measured radiated intensity at the applied input electrical power of 31 W from the optimized lamp is ∼2.5 mW cm−2, which results in the electrical to optical conversion efficiency as high as 12.5%. The bacterial efficiency of the developed lamp is also examined on pathogenic gram-positive (S. aureus) and gram-negative (E. coli) bacteria. Complete inactivation of S. aureus and E. coli has been achieved at a UV dose of 3 mJ/cm2 and 12 mJ cm–2, respectively. Morphological studies of treated bacteria have also been performed to correlate the results.

Sensing performance enhancement of plasmonic waveguide sensor using a bimodal strategy with digital Gaussian filter

In this paper, a novel bimodal strategy with digital Gaussian filter was proposed to improve the sensing performance of plasmonic waveguide sensor (PWG). The central angle of the bimodal spectrum is adopted rather than the traditional resonance angle. Compared with conventional noise reduction algorithm, the proposed digital Gaussian filter would transform resonance dip into bimodal spectrum and then improve both sensitivity and signal-to-noise ratio. Expected angle and FWHM (full width at half maximum) of Gaussian filter are two significant parameters to optimize sensing performance for each specific waveguide spectrum. The sensitivity and standard deviation of TM1 mode were measured as 90.715 deg/RIU and 7.515 × 10−5 deg, respectively, which are better than those of TM1 PWG sensor. Its RI resolution was then calculated to be 8.28 × 10−7 RIU, which is double-fold lower than that of TM1 PWG sensor, that is 1.73 × 10−6 RIU. For biosensing application, the limit of detection (LOD) of 29.15 mg/L, that is 0.16 mM, was obtained for glucose molecule, according to the three-fold standard deviation theory. For BSA detection, the LOD as high as 0.949 pM was achieved, which is approximately 2.8-fold lower than that of PWG sensor. It is also nearly two orders of magnitude lower than that of gold based SPR sensor, which is 91.33 pM.

Tunable broadband near-infrared emission from environmentally friendly Fe3+-activated lead-free perovskites for spectral analysis and rapid nighttime recognition

With the increasing role of near-infrared (NIR) light sources in many fields such as food and industry, NIR emitting phosphors have flourished in recent years. In addition to the widely reported Cr3+-activated NIR phosphors, environmentally friendly Fe3+ can also produce tunable broadband NIR spectra, which are expected to enrich the next generation of intelligent NIR light sources. In this work, a series of Fe3+-activated perovskite-type Sr2ScSbO6 (SSSO) NIR phosphors were successfully prepared and an emission wavelength of 900 nm with a full width at half maximum (FWHM) of 110 nm was obtained. Through the crystal field engineering strategy, the lattice site of Sr2+ was completely replaced by Ba2+ and Ca2+ to obtain Ba2ScSbO6 (BSSO) and Ca2ScSbO6 (CSSO), and the emission peak was continuously adjusted from 840 nm to 950 nm. When the temperature increased from 300 K to 400 K, BSSO:Fe3+, SSSO:Fe3+ and CSSO:Fe3+ could maintain 69 %, 82 % and 67 % of the original luminescence intensity, respectively. The opposite crystal field dependence between Fe3+ and Cr3+ was shown in double-layer perovskite-type antimonate materials, which could guide us to develop Fe3+-activated long-wavelength emission NIR phosphors. Benefiting from the long-wavelength emission of BSSO:Fe3+, SSSO:Fe3+, and CSSO:Fe3+, their application potential in the field of spectral analysis and rapid nighttime recognition were successfully demonstrated.

Peak Broadening in Photoelectron Spectroscopy of Amorphous Polymers: The Leading Role of the Electrostatic Landscape.

The broadening in photoelectron spectra of polymers can be attributed to several factors, such as light source spread, spectrometer resolution, the finite lifetime of the hole state, and solid-state effects. Here, for the first time, we set up a computational protocol to assess the peak broadening induced for both core and valence levels by solid-state effects in four amorphous polymers by using a combination of density functional theory, many-body perturbation theory, and classical polarizable embedding. We show that intrinsic local inhomogeneities in the electrostatic environment induce a Gaussian broadening of 0.2-0.7 eV in the binding energies of both core and semivalence electrons, corresponding to a full width at half-maximum (FWHM) of 0.5-1.7 eV for the investigated systems. The induced broadening is larger in acrylate-based than in styrene-based polymers, revealing the crucial role of polar groups in controlling the roughness of the electrostatic landscape in the solid matrix.

Modulating electronic confinement and structural distortion of multiple resonance emitters enables high-performance ultrapure blue OLED

Developing deep-blue emitters with high color purity is crucial for the advancement of ultrahigh-definition display technology based on organic light-emitting diodes (OLEDs). Since most emitters are empirically designed, establishing a feasible design strategy for developing ultrapure blue emitters with narrowband characteristics remains an urgent and challenging goal. Here, we subtly construct four blue emitters with multiple resonance (MR) effect and provide an in-depth understanding for the nature of narrowband emission from the perspective of electronic confinement and structural distortion combined with actual molecular structures. A novel and feasible molecular design strategy is proposed based on the “flexible locking-ring” concept, enabling effective narrowing main peak while retaining bluer emission. More impressively, a simple sensitizer-free OLED based on SAC2MN2B with the “flexible locking-ring” design achieves one of state-of-the-art device performance with a maximum external quantum efficiency of 19.80 %, and a pure deep-blue emission peaking at 448 nm with small full-width at half-maximum (FWHM) of 25 nm and CIE coordinates of (0.147, 0.061). This work successfully achieves high-performance OLED with high color purity and provides a feasible and promising design strategy for developing organic emitters with ultrapure blue emission.

Spectroscopic diagnostic of the footpoints of the cool loops

ABSTRACT Statistically, the cool loop’s footpoints are diagnosed using Si iv resonance lines observations provided by Interface Region Imaging Spectrograph (IRIS). The intensity and full width at half-maximum (FWHM) of the loop’s footpoints in β–γ active regions (ARs) are higher than the corresponding parameters of footpoints in β ARs. However, the Doppler velocity of footpoints in both ARs are almost similar to each other. The intensities of footpoints from β–γ AR is found to be around nine times that of β AR when both ARs are observed nearly at the same time. The same intensity difference reduces nearly to half (four times) when considering all ARs observed over 9 yr. Hence, the instrument degradation affects comparative intensity analysis. We find that Doppler velocity and FWHM are well correlated while peak intensity is neither correlated with Doppler velocity nor FWHM. The loop’s footpoints in β–γ ARs have around four times more complex Si iv spectral profiles than that of β ARs. The intensity ratios (Si iv 1393.78 Å/1402.77 Å) of the significant locations of footpoints differ, marginally, (i.e. either less than 1.9 or greater than 2.10) from the theoretical ratio of 2, i.e. 52 per cent (55 per cent) locations in β (β–γ) ARs significantly deviate from 2. Hence, we say that more than half of the footpoint locations are either affected by the opacity or resonance scattering. We conclude that the nature and attributes of the footpoints of the cool loops in β–γ ARs are significantly different from those in β ARs.

Efficient Deep‐Blue Light‐Emitting 2D (100)‐Oriented Perovskites and Spectral Broadening by Exciton Self‐Trapping for White‐light Emissions

AbstractEfficient narrow deep‐blue and broadband emissions in layered 2D organic–inorganic hybrid metal halide perovskites (MHPs) are attracting more attention and need further study. In this work, two (100)‐oriented 2D organic‐inorganic hybrid MHPs of (TFI)2PbBr4 and (TFI)2PbCl4·H2O (TFI = 4‐(trifluoromethyl)‐1H‐imidazole) with efficient deep‐blue and bluish‐white emissions are synthesized and the photoluminescence quantum yields (PLQYs) reached up to 81.21% and 20.23%, respectively. As both intrinsic lattice distortions of two crystals with similar crystal structure are almost negligible, they have theoretical deep‐blue emissions empirically. However, the halogen substitution of chlorine (Cl) by bromine (Br) broadened the deep‐blue photoluminescence to a bluish‐white area. Here, the spectral broadening phenomenon is discussed in detail. The (TFI)2PbBr4 film shows a narrow emission with a 16 nm full width at half maximum (FWHM) peaking at 435 nm upon excitation, and an ultraviolet‐pumped light‐emitting diode (LED) prepared by bluish‐white (TFI)2PbCl4·H2O phosphor shows a color rendering index (CRI) of ≈93 and a related color temperature (CCT) of 4162K, indicating their potential applications in deep‐blue and white LEDs, respectively.

Site Preference Induced Dual‐Wavelength Mn2+ Upconversion in K2NaScF6:Yb3+, Mn2+ and Its Application in Temperature Sensing

AbstractThe realization of dual‐wavelength Mn2+ upconversion (UC) luminescence that exhibits different thermal responsive behaviors is promising for non‐invasive optical temperature sensing applications. However, it remains challenging to achieve such luminescence of Mn2+ ions. Herein, due to the site preference characteristics of Mn2+, color tunable and dual‐wavelength Mn2+ UC luminescence is achieved in K2NaScF6:Yb3+, Mn2+ by simply adjusting the Mn2+ doping concentration. Structural and spectral analysis as well as theoretical calculations reveal that the green and red UC emissions originate from two kinds of face‐sharing Yb3+‐Mn2+ dimers, which exhibit different luminescence properties, including different emission wavelength, excited state lifetime, full width at half maximum (FWHM), and luminescence thermal stability. This unique dual‐wavelength UC luminescence of Mn2+ provides a new type of fluorescence intensity ratio thermometer with absolute and relative sensitivities of up to 0.018 K−1 and 0.525% K−1, respectively. This work not only demonstrates the potential application of K2NaScF6:Yb3+, Mn2+ material in the field of optical thermometry but also provides new perspectives for designing multi‐band Mn2+ UC luminescence.

Nanocrystalline Lead Halide Perovskites to Boost Time‐of‐Flight Performance of Medical Imaging Detectors

AbstractTime‐of‐flight (TOF) technique, traditionally used in high energy physics (HEP) and positron emission tomography (PET), is now being explored for lower energy applications like computed tomography (CT). Regardless of the application, pushing the current boundaries in time resolution calls for novel technologies and materials exhibiting ultra‐fast time response. Semiconductor nanocrystals like cesium lead halide perovskites (CsPbBr3), benefiting from quantum confinement effects, feature ultra‐fast decay and, when combined with a suitable bulk scintillator following a heterostructure concept, can also provide the necessary stopping power. In this work, thin films of CsPbBr3 on top of BGO, LYSO:Ce, and GAGG:Ce,Mg wafers are fabricated to test their impact on the single crystal scintillator time resolution under soft X‐rays excitation (about 10 keV). It is demonstrated that the CsPbBr3 layer significantly improves the overall time resolution in all cases, achieving up to a tenfold improvement with BGO and GAGG:Ce,Mg. Under 511 keV γ‐rays, a proof‐of‐concept of the heterostructure design for TOF‐PET using CsPbBr3 thin film deposited on GAGG:Ce,Mg bulk crystal is successfully tested. Shared events depositing energy in both materials are identified, resulting in more than twofold improved coincidence time resolution: 118 ± 4 ps full‐width‐at‐half‐maximum (FWHM) compared to the 272 ± 8 ps of solely GAGG:Ce,Mg.

Reduction of cone-beam CT artifacts in a robotic CBCT device using saddle trajectories with integrated infrared tracking.

Cone beam computed tomography (CBCT) is widely used in many medical fields. However, conventional CBCT circular scans suffer from cone beam (CB) artifacts that limit the quality and reliability of the reconstructed images due to incomplete data. Saddle trajectories in theory might be able to improve the CBCT image quality by providing a larger region with complete data. Therefore, we investigated the feasibility and performance of saddle trajectory CBCT scans and compared them to circular trajectoryscans. We performed circular and saddle trajectory scans using a novel robotic CBCT scanner (Mobile ImagingRing (IRm); medPhoton, Salzburg, Austria). For the saddle trajectory, the gantry executed yaw motion up to using motorized wheels driving on the floor. An infrared (IR) tracking device with reflective markers was used for online geometric calibration correction (mainly floor unevenness). All images were reconstructed using penalized least-squares minimization with the conjugate gradient algorithm from RTK with voxel size. A disk phantom and an Alderson phantom were scanned to assess the image quality. Results were correlated with the local incompleteness value represented by , which was calculated at each voxel as a function of the source trajectory and the voxel's 3D coordinates. We assessed the magnitude of CB artifacts using the full width half maximum (FWHM) of each disk profile in the axial center of the reconstructed images. Spatial resolution was also quantified by the modulation transfer function at 10% (MTF10). When using the saddle trajectory, the region without CB artifacts was increased from 43 to 190mm in the SI direction compared to the circular trajectory. This region coincided with low values for . When was larger than 0.02, we found there was a linear relationship between the FWHM and . For the saddle, IR tracking allowed the increase of MTF10 from 0.37 to 0.98 lp/mm. We achieved saddle trajectory CBCT scans with a novel CBCT system combined with IR tracking. The results show that the saddle trajectory provides a larger region with reliable reconstruction compared to the circular trajectory. The proposed method can be used to evaluate other non-circulartrajectories.

Secondary donor-acceptor group enable efficient pure green organic light-emitting devices based on multi-resonance TADF emitters

Multi-resonance thermally activated delayed fluorescence (MR-TADF) presents great potential for applications in high-quality organic light emitting diodes (OLEDs) displays due to their superb properties of high color purity and high quantum efficiencies. Nonetheless, most reported MR-TADF emitters show unsatisfactory devices performances with severe efficiency roll-off resulted from their inherent issues of slow reverse intersystem crossing rate (kRISC) and aggregation-caused quenching (ACQ). Herein, we propose a novel strategy by employing quinazoline derivatives as secondary acceptor (PQ) and secondary donor–acceptor (PQCz) to provide intermediate locally excited triplet (3LE) states and then enhance spin-orbital coupling (SOC). In addition, the secondary donor–acceptor group PQCz in tCzBN-PQCz can suppress intermolecular interaction and provide dual long-range charge transfer (LRCT) channels to further enhance kRISC. Therefore, tCzBN-PQ and tCzBN-PQCz exhibit high kRISC of 5.6 × 105 s−1 and 7.3 × 105 s−1 with large photoluminescence quantum yield (PLQY) of 89 % and 95 % respectively. Consequently, OLED based on tCzBN-PQ and tCzBN-PQCz show excellent external quantum efficiency (EQE) of 30.2 % and 35.1 % with small efficiency roll-off and small full width at half maxima (FWHM) of 37 nm and 34 nm respectively. Especially, tCzBN-PQCz exhibits better performances and less-sensitive to the doping concentration which proves the effectiveness of this secondary donor–acceptor group.