Fluorescence Emission Research Articles

Comparative Study of Two Spectral Methods for Estimating the Excited State Dipole Moment of Non-Fluorescent Molecules.

The electronic absorption spectral characteristics of cycloimmonium ylids with a zwitterionic structure have been analyzed in forty-three solvents with different hydrogen bonding abilities. The two ylids lack fluorescence emission but are very dynamic in electronic absorption spectra. Using the maximum of the ICT band, the goal was to establish an accurate relationship between the shift of the ICT visible band and the solvent parameters and to estimate two of the descriptors of the first (the) excited state: the dipole moment and the polarizability. Two procedures were involved: the variational method and the relationships of the Abe model. The results indicate that the excited state dipole moment of the two methylids decreases in the absorption process in comparison with the ground state. The introduction of a correction term in the Abe model that neglects the intermolecular H-bonding interactions leads to a more accurate determination of the two descriptors. The strong solvatochromic response of both ylids has been further applied in distinguishing the solvents as a function of their specific parameters. Principal component analysis was applied to five selected properties, including the maximum of the charge transfer band. The results were further applied to discriminate several binary solvent mixtures.

Cryo-Fluorescence Tomography as a Tool for Visualizing Whole-Body Inflammation Using Perfluorocarbon Nanoemulsion Tracers.

We explore the use of intravenously delivered fluorescent perfluorocarbon (PFC) nanoemulsion tracers and multi-spectral cryo-fluorescence tomography (CFT) for whole-body tracer imaging in murine inflammation models. CFT is an emerging technique that provides high-resolution, three-dimensional mapping of probe localization in intact animals and tissue samples, enabling unbiased validation of probe biodistribution and minimizes reliance on laborious histological methods employing discrete tissue panels, where disseminated populations of PFC-labeled cells may be overlooked. This methodology can be used to streamline the development of new generations of non-invasive, cellular-molecular imaging probes for in vivo imaging. Mixtures of nanoemulsions with different fluorescent emission wavelengths were administered intravenously to naïve mice and models of acute inflammation, colitis, and solid tumor. Mice were euthanized 24 h post-injection, frozen en bloc, and imaged at high resolution (~ 50 µm voxels) using CFT at multiple wavelengths. PFC nanoemulsions were visualized using CFT within tissues of the reticuloendothelial system and inflammatory lesions, consistent with immune cell (macrophage) labeling, as previously reported in in vivo magnetic resonance and nuclear imaging studies. The CFT signals show pronounced differences among fluorescence wavelengths and tissues, presumably due to autofluorescence, differential fluorescence quenching, and scattering of incident and emitted light. CFT is an effective and complementary methodology to in vivo imaging for validating PFC nanoemulsion biodistribution at high spatial localization, bridging the resolution gap between in vivo imaging and histology.

Enhancement of non-covalent interaction between soy protein isolate and quercetin by sodium alginate

Effects of sodium alginate (SA) on the non-covalent interaction between soybean protein isolate (SPI) and quercetin (Que) were investigated by multispectral technology, molecular docking and dynamics simulation technology. Structural alterations of the binary complexes were observed after SA addition, characterized by a red shift of maximum fluorescence emission wavelength. The introduction of 0.1% (w/v) SA led to a reduction of 12.3% in the α-helix and β-sheet structures, accompanied by 12.6% increase in the β-turn and random coil conformations. The binding of SA to SPI provided electrostatic interactions and facilitated the subsequent binding of SPI to Que. Molecular docking confirmed that hydrophobic interactions and electrostatic interactions were also the main driving force. Molecular dynamics simulation emphasized that the ternary complexes with SA exhibited greater stability compared to the binary ones. The foaming and emulsifying properties of SPI-Que complexes were enhanced by 33.76% and 68.28%, respectively, due to the addition of SA.

Fine-tuning the photophysical properties of Imidazo[1,2-a]pyridine-based dyes by the change in substituent and solvent media: DFT and TD-DFT studies

In the present work, photophysical properties of the nine excited-state intramolecular proton transfer (ESIPT) active 2-(2 -hydroxyphenyl)imidazo[1,2-a]pyridine (HPIP)-based dyes A1-A9 (X= H, Me, F, Cl, OMe, OH, CN, NO2 and CF3) were investigated at PBE0/6-31++G(d,p) and M06-2X/6-31++G(d,p) levels of theory in the gas phase and solvent media. The structural parameters, relative energies, vibrational spectra, photophysical properties, potential energy curves, natural bond orbital (NBO) charges, hole and electron isosurfaces, electron density properties and reduced density gradient (RDG) spikes were computed. The H-bonding is strengthened at the S1 state by comparing infrared vibrational spectra, the relevant bond length and bond angle, electron density properties and RDG analysis. The results revealed that ESIPT in the A1-A7 and A9 in the gas phase is a barrier-less process, while there is an energy barrier for the A8 (X=NO2). In polar solvents, it is predicted that the ESIPT process only in A5 and A6 is a barrier-less process. The A2, A4 and A5 exhibited the greatest redshift in the keto fluorescence emission in tetrahydrofuran solvents. The significant Stokes shift observed in the S1-K emission of certain dyes makes these molecules highly appealing for various applications such as chemosensors, fluorescent probes, laser dyes and optoelectronic devices.

Biomass-derived multiatom-doped carbon dots for water sensing based on excited state intraparticle proton transfer in organic solvents

The presence of trace water impurities in organic solvents can significantly influence chemical reactions and product quality; thus, the accurate detection of water content in these solvents is a critical requirement for industrial applications. Accordingly, an eco-friendly, effective, and economical sensor for detecting trace quantities of miscible water in organic solvents is required for industrial applications. In this study, we synthesized biomass-derived multi-atom-doped carbon dots (MACDs) as fluorescent probes and employed them for the detection of trace amounts of water impurities in several water-miscible organic solvents. The MACDs exhibited stable dual-color fluorescence emission under ultraviolet light irradiation and red and blue emissions in organic solvents and water. The fluorescence quantum yield was approximately 11 %, which indicates an excited intraparticle proton transfer response due to an increase in the water content within a wide response range from 0 % to 100 % (v/v) in organic solvents. The intensity of the red emission signal at 670 nm gradually decreased with an increase in the water content in the organic solvent. The MACDs could detect water with an instant response time of 55 s, a high sensitivity, and low limits of detection of 0.08 %, 1.36 %, 0.03 %, 0.04 %, 0.12 %, and 0.05 % (v/v) in ethanol, acetonitrile, dimethylformamide, methanol, isopropanol, and tetrahydrofuran, respectively. Hence, biomass-derived MACDs can serve as efficient and eco-friendly water sensors in organic solvents.

Ecofriendly micellar mediated spectrofluorimetric method for ultrasensitive quantification of the antiparkinsonian drug safinamide in pharmaceutical formulation and spiked human plasma

A novel, highly sensitive and eco-friendly micellar-mediated spectrofluorimetric method was developed and validated for the determination of the novel antiparkinsonian drug safinamide mesylate in the presence of its related precursor impurity, 4-hydroxybenzaldehyde. The proposed approach relies on increasing the inherent fluorescence emission at 296 nm of safinamide, by forming hydrogen bonds between the mentioned drug and sodium dodecyl sulfate in the micellar system using 0.1 N HCl as a solvent, following excitation at 226 nm. A thorough investigation was conducted into the experimental factors affecting spectrofluorimetric behavior of the studied drug. A linearity plot of safinamide over the concentration range of 10.0–1000.0 ng/mL against the relative fluorescence intensities was established. The proposed method demonstrated excellent sensitivity down to the nano-gram level with detection and quantitation limits of 1.91 and 5.79 ng/mL, respectively. The studied drug was effectively determined in Parkimedine® Tablets. Furthermore, the proposed method allows for ultrasensitive quantification of safinamide in spiked human plasma, with satisfactory percentage recovery (98.97–102.28%). Additionally, the greenness assessment using the advanced green certificate classification approach, the complementary green analytical procedure index (Complex-GAPI), and the analytical GREEness metric approach (AGREE), along with the practicality check using the Blue Applicability Grade Index in addition to the all-inclusive overall whiteness evaluation using the RGB-12 model were carried out. The outcomes demonstrated the effectiveness and whiteness of the proposed technique. Clearly, the suggested approach has the advantages of being simple, requiring no pretreatment steps, and relying solely on direct measuring procedures.

Introducing steric groups to thermally activated delayed fluorescence emitter for constructing efficient non-doped solution-processed organic light-emitting diodes

Solution-processed organic light-emitting diodes (OLEDs) remain a reliable approach towards large-area and flexible display devices, but also hold higher requirement on luminescent materials. It is still challenge to develop emitting layers with great solution-processable property and excellent luminous behavior, and especially difficult for non-doped emitting materials. In this work, a TADF emitter, namely 2,3,5,6-tetrakis(4-([1,1':3′,1″-terphenyl]-5′-yl)-9H-carbazol-9-yl)benzonitrile (3Ph-4CzBN), was designed and synthesized by introducing the steric-hindrance triphenyl unit to 2,3,5,6-tetrakis(carbazol-9-yl) benzonitrile (4CzBN) which is usually applied to vacuum evaporation. The incorporation of triphenyl groups significantly increased the molecule weight, thereby rendering 3Ph-4CzBN suitable for solution-processed OLEDs. Meanwhile, 3Ph-4CzBN exhibited two-fold of photoluminescence quantum yield values in pure film than 4CzBN, indicating fluorescence quenching was relatively suppressed by steric groups. The solution-processed OLEDs employed 3Ph-4CzBN as non-doped emitting layer, achieved a maximum external quantum efficiency of 12.8 %, as well as current efficiency and power efficiency up to 34.2 cd A−1 and 23.9 lm W−1, respectively.

Color class and structure-related observable fluorescence response in arctic macroalgae as coastal underwater lidar substrates

In the context of underwater marine biological remote sensing surveys, we consider the fluorescence response of macroalgal and kelp targets to underwater fluorescence laser serial and lidar imaging applications. An investigation of absorption and fluorescence emission via excitation–emission (EEM) spectra of Arctic macroalgal substrates is presented via naturally and artificially generated structural scenarios. Fluorescence was found to increase with algal structure thickness for the kelp Alaria esculenta, both when its output is tested with or without structural modification (increase thickness) of the kelp thallus. Several trials involving other species of all three color classes showed fluorescence output decreased after a thickness increase via layering or structure reconfiguration: a process we suggest is due to fluorescence re-absorption sometimes occurring within and between the rearranged algal structures.

Optical characterization of black carbon-derived DOM: Implication for the fluorescence detection of fuel combustion products in marine waters

Among pollutants released from shipping, black carbon (BC), also known as soot carbon, is of great interest due to its impacts on climate, air quality, human health and ecosystems. BC emitted from ships may enter marine waters and partially transfer to the seawater dissolved phase. In this study, we investigated the optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) derived from BC particles (DOMBC) emitted by ships, which were compared to those of DOMBC of other origins (diesel-powered industrial machine, biomass burning, urban dust), and to terrestrial and marine DOM (DOMTER, DOMMAR). Ship and diesel DOMBC displayed higher ratios of fluorescence maximum intensity to dissolved organic carbon concentration (Fmax/DOC), higher specific UV absorbance at 254 nm (SUVA254), and lower fluorescence emission wavelengths than the other tested materials. The parallel factor analysis (PARAFAC)-derived fluorophores of the ship and diesel DOMBC exhibited significant correlations with the concentration of dissolved black carbon (DBC), determined using the benzenepolycarboxylic acid (BPCA) method. Based on these results, we propose the Combustion indeX (COX), to help detecting and tracking ship/fuel combustion pollutions in marine waters.

Spectroscopic and statistical physics elucidation for Cu(II) remediation using magnetic bio adsorbent based on Fe3O4-chitosan-graphene oxide

Efficient harnessing of heavy metal pollution is an urgent environmental task. Herein, magnetic bio adsorbent (MB) based on Fe3O4-chitosan-graphene oxide composite was fabricated via one step co-precipitation for adsorptive remediation of Cu(II). Remediation efficiency was evaluated by batch adsorption, meanwhile adsorption mechanism was elucidated by spectroscopic tests (XPS, UV–Vis absorption and fluorescent emission spectra), statistical physics formalism, isotherm and kinetic fittings. Results show, MB reaches adsorption percent and quantity of 87.61 % and 350.43 mg·g−1 for Cu(II) in 30 min. By virtue of paramagnetism, MB can be readily recovered with a permanent magnet for easy regeneration and cyclic use, thereby retaining adsorption quantity 279.99 mg·g−1 at the fifth cycle. The Freundlich and pseudo second order model satisfactorily describes the adsorption, designating chemical interaction as the rate limiting step. Statistical physics calculation suggests two points. (1) Multi-ionic adsorption mechanism with exothermic, spontaneous and energy lowering feature. (2) Density of adsorption sites increases with temperature, resulting in improved adsorption capacity. Spectroscopic analysis confirms the involvement of CO, CO, -NH2 in Cu(II) uptake via electron donation. These explorations contribute with novel theoretical illumination for understanding both the thermodynamic feature and atomic scale mechanism of common pollutants adsorption by bio adsorbent like Fe3O4-chitosan-graphene oxide.

Vibronic splitting of the electronic origin in two conformers of the 3-tolunitrile dimer.

3-tolunitrile (3-TN) can from three different dimers, which differ in the relative orientation of the methyl groups. We determined the geometry changes of two of these conformers of 3-TN upon electronic excitation via a Franck-Condon fit of the vibronic intensities in the fluorescence emission spectra. Both aromatic rings expand upon electronic excitation, showing a delocalized one-photon excitation of the cluster. The conformer with the smaller COM distance shows an unusual order of the split components of the electronic origin. We attribute this changed order to the stronger CT contributions to the splitting and a partial breakdown of the point dipole approximation, made in the Frenkel type interaction.

A Diketopyrrolopyrrole-Based All-in-One Nanoplatform for Self-Reinforcing Mild Photothermal Therapy Cascade Immunotherapy for Tumors.

Mild photothermal therapy (PTT) has attracted attention for effectively avoiding the severe side effects associated with high-temperature tumor ablation. However, its progress is hindered by the limited availability of high-performance photothermal agents (PTAs) and the thermoresistance of cancer cells induced by heat shock reactions. Herein, this work proposes a new strategy to expand the library of high-performance organic small-molecule PTAs and utilize it to construct a multifunctional nano-theranostic platform. By incorporating additional acceptors and appropriate π-bridges, a diketopyrrolopyrrole-based dye BDB is developed, which exhibits strong absorption and bright fluorescence emission in the near-infrared (NIR)region. Subsequently, BDB is co-coated with the heat shock protein (HSP) inhibitor tanespimycin (17-AAG) using the functional amphiphilic polymers DSPE-Hyd-PEG2000-cRGD to form an all-in-one nanoplatform BAG NPs. As a result, BAG NPs can precisely target tumor tissue, guide the treatment process in real-time through NIR-II fluorescence/photoacoustic/photothermal imaging, and release 17-AAG on demand to enhance mild PTT. Additionally, the mild PTThas been demonstrated to induce immunogenic cell death (ICD) and activate a systemic anti-tumor immune response, thereby suppressing both primary and distant tumors. Overall, this study presents a multifunctional nanoplatform designed for precise mild PTT combined with immunotherapy for effective tumor treatment.

Predicting Emission Wavelengths in Benzobisoxazole-Based OLEDs with Gradient Boosted Ensemble Models.

We demonstrate the use of gradient-boosted ensemble models that accurately predict emission wavelengths in benzobis[1,2-d:4,5-d']oxazole (BBO) based fluorescent emitters. We have curated a database of 50 molecules from previously published data by the Jeffries-EL group using density functional theory (DFT) computed ground and excited state features. We consider two machine learning (ML) models based on (i) whole cruciform molecules and (ii) their constituent fragment molecules. Both ML models provide accurate predictions with root-mean-square errors between 30 and 36 nm, competitive with state-of-the-art deep learning models trained on orders of magnitude more molecules, and this accuracy holds even when tested on four new BBO emitters unseen by the models. We also provide an interpretable feature importance analysis and discuss the relevant relationships between DFT and changes in predicted emission wavelength.

Understanding Spin-Triplet Excited States in Carbene-Metal-Amides.

Carbene-metal-amides (CMAs) are emerging delayed fluorescence materials for organic light-emitting diode (OLED) applications. CMAs possess fast, efficient emission owing to rapid forward and reverse intersystem crossing (ISC) rates. The resulting dynamic equilibrium between singlet and triplet spin manifolds distinguishes CMAs from most purely organic thermally activated delayed fluorescence emitters. However, direct experimental triplet characterization in CMAs is underutilized, limiting our detailed understanding of the ISC mechanism. In this work, we combine time-resolved spectroscopy with tuning of state energies through environmental polarity and metal substitution, focusing on the interplay between charge-transfer (3CT) and local exciton (3LE) triplets. Unlike previous photophysical work, we investigate evaporated host : guest films of CMAs and small-molecule hosts for increased device relevance. Transient absorption reveals an evolution in the triplet excited-state absorption (ESA) consistent with a change in orbital character between hosts with differing dielectric constants. Using quantum chemical calculations, we simulate ESAs of the lowest triplet states, highlighting the contribution of only 3CT and donor-moiety 3LE states to spectral features, with no strong evidence for a low-lying acceptor-centered 3LE. Thus, our work provides a blueprint for understanding the role of triplet excited states in CMAs which will enable further intelligent optimization of this promising class of materials.

2,3:6,7‒Naphthalene bis(dicarboximide) Cyclophane: A Photo‒functional Host for Ambient Delayed Fluorescence in Solution.

Harvesting triplet excitons of heavy atom-free purely organic chromophores under aerated conditions is challenging due to the quenching of long-lived triplet states by molecular oxygen and vibrational dissipation. Herein, we show a supramolecular approach of triplet harvesting via mitigating quenching pathways of a triplet harvester. Specifically, we used a host-guest system based on 2,3:6,7‒naphthalene bis(dicarboximide)-derived cyclophane (NBICy) and carbazole derivative (EtCz). Complexation studies and single-crystal X-ray analysis showed the formation of a rigid host-guest complex (K= ~104 M-1 in CCl4), resulting in triplet-exciton stabilization under aerated conditions via mitigating vibrational interference and oxygen quenching. Photophysical studies elucidate the delayed fluorescence emission from the charge-transfer state (1CT) with a quantum yield (QY) of 6-8% under ambient conditions which increased up to 36 % in an inert atmosphere.

Versatile Solvatochromic fluorophores based on Schiff bases for colorimetric detection of metal ions

In recent years, fluorescent probes have been extensively studied as powerful tools for the effective assessment of toxic metal ions due to their high sensitivity, selectivity, capability for real-time and non-invasive monitoring, and versatility. In this paper, novel fluorescent probes based on Schiff bases, namely 2-((1E,2E)-1-(6-chlorobenzo[d]thiazol-2-ylimino)-3-(4-(dimethylamino)phenyl)allyl)phenol (1) and 2-((1E,2E)-3-(4-(dimethylamino)phenyl)-1-(4-methylbenzo[d]thiazol-2-ylimino)allyl)phenol (2), were synthesized and characterized. The optical properties of these probes were examined across a spectrum of fourteen solvents with varying polarities, revealing significant solvatochromic effects on both absorption and fluorescence spectra. The analysis delineated a discernible difference in dipole moment between electronic ground and excited states, with molecules exhibiting enhanced stabilization in singlet excited states. Subsequently, a straightforward method was devised for the selective and sensitive detection of diverse metal ions in aqueous solutions, including K+, V3+, Cr3+, Fe3+, Co2+, Ni2+, Cu2+, Se6+, Cd2+, Ba2+, and Hg2+, through naked eye observation, UV–Visible, and fluorimetric measurements. Notably, the UV–Vis spectra of probes 1 and 2 manifested a significant red shift upon the addition of metal ions, indicative of potential ligand-to-metal charge-transfer (LMCT) phenomena, with the exception of Ni2+, Cu2+, and Se6+ions. The observed alterations in optical absorption and fluorescence emission contributed to the probes' heightened selectivity and sensitivity, obviating the necessity for sample pretreatment. Competitive assays underscored the probes' preference for Cr3+ and V3+ ions over other common metal ions. Furthermore, Job's plot analysis suggested a 1:1 ligand-to-metal molar ratio binding. The investigated Schiff bases exhibited elevated binding constants (Ka), low detection limits, and limits of quantification, alongside diminished fluorescence quantum yield. Leveraging fluorescence quenching, facile paper-based sensor strips coated with Schiff bases facilitated prompt, qualitative, and quantitative in situ detection of metal ions in aqueous solutions across a broad concentration spectrum, discernible to the naked eye under UV light.

Bifunctional materials based on poly(3-aminocarbazole) for efficient and highly selective detection and adsorption of Hg2+ in water

Herein, two poly(3-aminocarbazole) derivatives containing imidazole N-type acceptor were synthesized and reported, which are named PCPI and PCBI respectively. The fluorescence spectrum shows that PCPI (Em = 498 nm) and PCBI (Em = 398 nm) both have a strong fluorescence emission. It is worth noting that PCPI has a larger stokes shift of 153 nm, which is beneficial for improving the sensitivity of the sensor and enhancing its anti-interference ability. As expected, our experimental results indicate that both PCPI and PCBI can cause a specific response of “fluorescence OFF” to Hg2+ compared with other ions. And PCPI and PCBI both have excellent detection capabilities for Hg2+, with detection limits of 69.8 nM and 11.4 nM respectively. Moreover, PCBI exhibits excellent absorption of Hg2+ with a maximum absorption capacity of 477.8 mg/g at 20 °C. It indicates that PCBI can be used as a functional material for the detection and removal of Hg2+ in water.

Mesoscale Acid-Base Complexes Display Size-Associated Photophysical Property and Photochemical Activity.

The properties of single molecules and molecular aggregates can differ dramatically, leading to a long-standing interest in mesoscale aggregation processes. Herein, a series of acid-base molecular complexes is developed by using a tetraphenylethylene-backboned fluorophore, and investigated the photophysical properties and photochemical activities at different aggregation length scales. This fluorophore, with two basic diethylamine groups and two acidic tetrazole groups, exhibits sparse solubility due to multivalent interactions that cause infinite aggregation. The addition of a third acid leads to the formation of fluorophore/acid complexes with good dispersibility and colloidal stability. This assembly process can be controlled by the use of different acids and their stoichiometry, resulting in aggregates ranging in size from a few to hundreds of nanometers. A crystalline structure is obtained to illustrate the complex properties of the acid-base network. Unlike the single molecule, these complexes show a trend of size-related properties for photoluminescence efficiency and photochemical activity. As the amount of acid added increases, the size of the complexes decreases, the aggregation effect of the complexes on fluorescence emission increases, and the rates of the oxidative photocyclization and photodecomposition slow down. This work may help to understand size-controlled molecular materials at the mesoscale for functional design.

2,3:6,7‒Naphthalene bis(dicarboximide) Cyclophane: A Photo‒functional Host for Ambient Delayed Fluorescence in Solution

Harvesting triplet excitons of heavy atom‐free purely organic chromophores under aerated conditions is challenging due to the quenching of long‐lived triplet states by molecular oxygen and vibrational dissipation. Herein, we show a supramolecular approach of triplet harvesting via mitigating quenching pathways of a triplet harvester. Specifically, we used a host–guest system based on 2,3:6,7‒naphthalene bis(dicarboximide)‐derived cyclophane (NBICy) and carbazole derivative (EtCz). Complexation studies and single‐crystal X‐ray analysis showed the formation of a rigid host–guest complex (K = ~104 M‐1 in CCl4), resulting in triplet‐exciton stabilization under aerated conditions via mitigating vibrational interference and oxygen quenching. Photophysical studies elucidate the delayed fluorescence emission from the charge‐transfer state (1CT) with a quantum yield (QY) of 6‐8% under ambient conditions which increased up to 36 % in an inert atmosphere.

Tetra‐Donor Pyrazine Based Thermally Activated Delayed Fluorescence Emitters for Electroluminescence and Amplified Spontaneous Emission

AbstractThermally activated delayed fluorescence (TADF) materials are expected to address triplet‐related losses in electrically driven organic lasers, as the electrically generated triplets in the materials can be converted to radiative singlets through reverse intersystem crossing (RISC). This offers a way to bypass triplet absorption and annihilation in organic semiconductor lasers (OSLs). In this work, two versatile TADF emitters 4tCzPz and 4αCbPz for application in organic light‐emitting diodes (OLEDs) and OSLs are presented. Both emitters possess moderately high singlet‐triplet energy gap, ΔEST (≈0.30 eV) and show high photoluminescence quantum yields, ΦPL, in solution and solid‐state and prominent stimulated emission features in solution. Films of 4tCzPz and 4αCbPz doped in mCBP show an amplified spontaneous emission (ASE) threshold of 41.0 and 44.9 µJ/cm2, respectively. The OLEDs with 4tCzPz and 4αCbPz emit with peak wavelengths of 492 and 475 nm, respectively, and show corresponding maximum external quantum efficiencies, EQEmax, of 24.6 and 21.3%. The research shows that D‐A TADF materials hold significant potential not only as emitters for OLEDs but also in OSLs.