Rong-Huei Yi

A highly emissive aluminum(III)-TADF complex with β-diketone ligands as a superior sensitizer for multi-resonance (MR)-TADF emitter is developed. This Al complex enables to sensitize yellow MR-TADF emitter yielding a near-unity PLQY and is used to fabricate a solution-processed hyper OLED with EQE of 21.6% and FWHM of 45 nm.

Abstract

Although Earth-abundant, ubiquitous, metal-based thermally activated delayed fluorescence (TADF) complexes are among the most promising candidate materials for next-generation organic light-emitting devices (OLEDs), few complexes are explored. Herein, a highly emissive aluminum(III)-TADF complex—Al(MCzDBM)₃ —with three β-diketone ligands is presented as a sensitizer for multiresonance (MR)-TADF emitters. This complex exhibited green emission with suitable photophysical functions as a sensitizer, such as a high photoluminescent quantum yield (PLQY) of up to 97% with reduced aggregation-caused quenching, a high radiative rate constant (k _r) of 5.6 × 10⁷ s⁻¹, and a short delayed lifetime (τ_d) of 4.0 µs in the solid state. A solution-processed Al(MCzDBM)₃ -based OLED exhibited an external quantum efficiency (EQE) of 23.6%. This complex sensitized a yellow MR-TADF emitter, yielding a near-unity PLQY, and is used to fabricate a solution-processed hyperfluorescent OLED with an EQE of 21.6% and full width at half maximum of 45 nm.

The operational lifetime of thermally activated delayed fluorescence (TADF) assisted fluorescence organic light-emitting devices (TAF-OLEDs), also known as hyperfluorescence OLEDs, is governed by the intrinsic stability of constituent materials. Chemical investigations disentangle the degradation processes mediated by excitons and polarons in TAF-OLEDs involving TADF molecules as exciton sensitizers.

Abstract

Thermally activated delayed fluorescence (TADF) assisted fluorescence organic light-emitting devices (TAF-OLEDs), also known as hyperfluorescence OLEDs, sometimes have limited operational lifetimes, making them unsuitable for industrial applications. Although, this limitation is believed to originate from the irreversible degradation of constituent materials, the chemical processes underlying this degradation remain elusive. This study enables to better understand the chemical origins of the degradation processes by identifying key degradation intermediates in emission layers comprising 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (TBRb) as the fluorescent emitter and 1,4-azaborin-based molecules exhibiting multi-resonance (MR) TADF behaviors, 5,9-diphenyl-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracene (DABNA-1) and 9-([1,1′-biphenyl]-3-yl)-N,N,5,11-tetraphenyl-5,9-dihydro-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracen-3-amine (DABNA-2), as exciton sensitizers. Despite the sensitizers facilitating energy transfer to TBRb, they also reduce the device's longevity. While the singlet and triplet excitons of TBRb, as well as excitons of the sensitizers, prove to be relatively stable, the radical ions of the sensitizers prove to be the key limit to device longevity. Comparisons with donor–acceptor-type TADF exciton sensitizers, 2,4,5,6-tetrakis(9H-carbazol-9-yl)benzene-1,3-dicarbonitrile (4CzIPN), 10,10′-(sulfonyldi-4,1-phenylene)bis[9,10-dihydro-9,9-dimethylacridine] (DMAC-DPS), and 10-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9,10-dihydro-9,9-dimethylacridine (DMAC-TRZ), corroborate the findings, pointing to radical ions as primary degradation intermediates. This knowledge is essential for enhancing the durability of TAF-OLEDs in future designs.

By incorporating a donor–accepter structure, the study introduced chiral units to create near-infrared emitting molecules ( S/R-ONTAP), endowed with circularly polarized luminescence properties. Simultaneously, the introduction of a twisted structure conferred upon these molecules remarkably high photoluminescence quantum yields and exceptional device performance in aggregated states.

Abstract

The exploration of organic near-infrared (NIR) luminescence, along with circularly polarized luminescence (CPL), is of vital importance due to its significance in medical and optoelectronic applications. Integrating a chiral unit into a D–A molecular structure in this research realized emission peaks at 744 nm, exhibiting a dissymmetric factor of −1.67 × 10⁻³. The introduced chiral TPA derivative not only imparts aggregation-induced emission properties and CPL capabilities but also induces a redshift in the emission spectrum. Consequently, the fabricated NIR organic light-emitting devices (OLEDs), achieve maximum electroluminescent peaks at 748 nm in nondoped devices with the external quantum efficiency of 13.7% in doped devices. This pioneering research provides inspiration for the design of NIR molecules possessing CPL properties in the future, particularly in promoting the application of intense NIR-OLEDs.

This work introduces a new concept to tailor the RISC of TADF emitters through their molecular geometry adaptation to crystalline hosts bearing a similar donor-acceptor structure. The approach significantly reduces the RISC activation energy, resulting in a remarkable tenfold boost of the RISC rate (above 10⁷ s⁻¹).

Abstract

Rapid reverse intersystem crossing (RISC) is one of the prime concerns for blue thermally activated delayed fluorescence (TADF) emitters, as it reduces triplet exciton population, the root cause of detrimental triplet-mediated annihilation processes that accelerate device efficiency roll-off and degradation. This work introduces a new concept to tailor the RISC of TADF emitters through their molecular geometry adaptation to crystalline hosts bearing a similar donor-acceptor structure. A meticulously designed crystalline host comprising isophthalonitrile acceptor (A) and carbazole-derived donor (D) units, characterized by nearly orthogonal D-A arrangement, has been demonstrated to alleviate singlet-triplet energy gap (ΔE_ST) of the TADF dopant by forcing it to adopt a more twisted D-A configuration, as corroborated by X-ray diffraction (XRD) measurements. The approach not only significantly reduces the RISC activation energy, resulting in a remarkable tenfold boost of the RISC rate (above 10⁷ s⁻¹) and fourfold shortening of delayed FL lifetime (down to 1.5 µs), but also offers the additional benefit of suppressing conformational disorder of TADF dopant, producing a narrower emission bandwidth. The presented concept, based on crystalline host-driven RISC engineering, is anticipated to have a profound impact on the development of high-performance, stable blue-emitting TADF organic light-emitting diodes (OLEDs).

High-performance organic photovoltaic (OVP) with efficiency exceeding 20% is achieved via the self-assembled interlayer (SAI) strategy. The use of 2PACz-SAI advances the surface/interface optoelectronic properties, including mitigated parasitic absorption, improved optical field distribution and the carrier dynamics. Moreover, the efficacy of SAI strategy is widely proved. Additionally, the 2PACz-SAI based ST-OPV exhibits a record light utilization efficiency of 5.34%.

Abstract

Interfacial layers (ILs) are prerequisites to form the selective charge transport for high-performance organic photovoltaics (OPVs) but mostly result in considerable parasitic absorption loss. Trimming the ILs down to a mono-molecular level via the self-assembled monolayer is an effective strategy to mitigate parasitic absorption loss. However, such a strategy suffers from inferior electrical contact with low surface coverage on rough surfaces and poor producibility. To address these issues, here, the self-assembled interlayer (SAI) strategy is developed, which involves a thin layer of 2–6 nm to form a full coverage on the substrate via both covalent and van der Waals bonds by using a self-assembled molecule of 2-(9H-carbazol-9-yl) (2PACz). Via the facile spin coating without further rinsing and annealing process, it not only optimizes the electrical and optical properties of OPVs, which enables a world-record efficiency of 20.17% (19.79% certified) but also simplifies the tedious processing procedure. Moreover, the SAI strategy is especially useful in improving the absorbing selectivity for semi-transparent OPVs, which enables a record light utilization efficiency of 5.34%. This work provides an effective strategy of SAI to optimize the optical and electrical properties of OPVs for high-performance and solar window applications.

Nature Photonics, Published online: 13 February 2024; doi:10.1038/s41566-024-01395-1

A comprehensive molecular family of diboron-based MR emitters incorporating carbazole/phenol resonant partners is established. The corresponding multi-color OLEDs exhibit high efficiency, ultralow efficiency roll-off, and exceptional operational stability.

Abstract

Diboron-based multi-resonance (MR) molecules featuring para-B-π-B configuration represent a highly promising class of emitters for red and near-infrared organic light-emitting diodes (OLEDs). The emission spectra of the diboron-based MR emitters can be fine-tuned by modulating the carbazole/phenol resonant partners. However, beyond spectral tuning, a comprehensive understanding of the intricate relationship between molecular structure, and the overall properties of diboron-based MR emitters remains elusive. In this work, through meticulous molecular design and precise material synthesis, the study has constructed three new MR emitters and completed the establishment of the diboron-based MR molecular family involving a carbazole/phenol resonant counterpart. These emitters facilitate a systematic investigation into the comprehensive impact of resonant partners on critical properties beyond spectral tuning, such as thermally activated delayed fluorescence, full-width at half-maximum, and horizontal orientation ratio. Eventually, by employing these emitters, high-performance narrowband emitting OLEDs with maximum external quantum efficiencies (EQE_maxs) of 30.2%, 33.0%, and 37.0% are fabricated for the green, yellow, and red devices, respectively, together with exceptional operational lifetimes. In particular, both yellow and red OLEDs exhibit unprecedented low-efficiency roll-off, maintaining high EQEs over 30% and 25% at the ultrahigh brightness levels of 10 000 and 100 000 cd m⁻², respectively.

DMA₄In_{1- x} Sb _x Cl₇ constructed via achiral units achieve bright white emission, near-unity PLQY and CPL with a g _lum of up to ±1.0 × 10⁻². The intrinsic chiral structures and associated spin-polarized energy levels, combined with complementary colors contribute to CPL and white emission. These findings provide new insights for perovskites with enhanced optical properties and applications in 3D displays, WLEDs, and anti-counterfeiting.

Abstract

Chiral organic-inorganic hybrid perovskites (OIHPs) exhibit exceptional optical and chiral properties, demonstrating potential for 3D display, circularly polarized light-emitting diodes (CP-LEDs), and CPL switches. However, the construction of chiral OIHPs often relies on chiral building blocks, limiting chemical diversity, and possessing challenges in achieving large asymmetry factor (g _lum) without sacrificing photoluminescence quantum yield (PLQY). Here, Chiral DMA₄In_{1- x} Sb _x Cl₇ (DMA = dimethylammonium, x = 0 to 1) with superior circularly polarized luminescence (CPL) are successfully constructed based on achiral building blocks DMA⁺ and metal halides. By optimizing the Sb³⁺ content, bright white emission with a high PLQY of 69.13% is achieved, as well as near-unity PLQY yellow emission and strong CPL signals with a g _lum of up to +1.40 × 10⁻², exhibiting a performance comparable to state-of-the-art chiral OIHPs. Combining optical characterizations and theoretical calculations reveal that these intriguing properties originate from the intrinsic chiral helical structures and a pair of perfect complementary color emissions in DMA₄In_{1- x} Sb _x Cl₇. In addition, DMA₄In_{1- x} Sb _x Cl₇ exhibit excellent thermal stability and mild thermal quenching in the temperature range of 300 to 420 K. These fascinating properties suggest that DMA₄In_{1- x} Sb _x Cl₇ have significant applications in white light-emitting diodes (WLED), 3D displays and anti-counterfeiting.

Universal biosafety and biostability concerns of polycations can be significantly diminished via controllable acryl-dopamine conjugation. With the improvement of toxicity, hemolysis, and immunogenicity, this facile strategy meanwhile boosts tunable fluorescence, white light emission, and metal-binding capability of various polycations, facilitating versatile live imaging tracking and positron emission tomography imaging-guided applications of polycations.

Abstract

As well known in bioactives delivery and cancer/inflammation theranostics, polycations have recently extended their biomedical potentials in reducing visceral fat, embolizing body fluid, modulating blood coagulation, and ameliorating hyperammonemia. However, positive charges that dominate various action mechanisms, often raise risks in biosafety concerns. Also, the lack of intrinsic imaging properties of polycations makes it challenging to uncover their pharmacokinetic profiles in living objects. Herein, dopamine conjugation is demonstrated controllable and highly efficient in boosting the fluorescence or even white color emission of various polycations including hyperbranched poly(amido amine) (HPAA), polyethyleneimine and poly-L-lysine. By shielding partial surface positive charges, increasing hydrophobicity, and inducing aqueous self-assembly, dopamine conjugation can significantly enhance the biocompatibility and decrease the toxicity and immunogenicity of polycations. Furthermore, the catechol-metal binding interaction facilitates the accessibility of polycation-based positron emission tomography (PET) probes. Different tissue uptake and biodistributions of gallium-68-radiolabeled HPAA before and after dopamine conjugation indicate that PET imaging can be a useful supplement to evaluate the dynamic toxicities of polycations.

Through decorating the MR-TADF core DiKTa with different PCP-based chiral groups, two pairs of chiral MR-TADF emitters, PCP-DiKTa and Czp-DiKTa, are synthesized. When applied, these two emitters into OLEDs, both of them show both narrow emission at 489 and 518 nm and high EQE_max of 25.7 and 29.2%.

Abstract

The study reports two pairs of chiral multi-resonant thermally activated delayed fluorescence (MR-TADF) materials PCP-DiKTa and Czp-DiKTa by decorating a known MR-TADF core, DiKTa, with different [2.2]paracyclophane (PCP) based planar chiral groups. PCP-DiKTa shows narrow sky-blue emission with a full width at half maximum (FWHM) of 44 nm, while the emission of Czp-DiKTa is slightly broader with a FWHM of 66 nm and redshifted. Both emitters show high photoluminescence quantum yields of 93 and 99% for PCP-DiKTa and Czp-DiKTa, respectively. Enantiomerically pure samples of both compounds show chiroptical properties in the ground state while only Czp-DiKTa exhibits chiroptical activity in the excited state, with dissymmetry factors (|g_PL|) of 4 × 10⁻⁴. Organic light-emitting diodes (OLEDs) with PCP-DiKTa and Czp-DiKTa show maximum external quantum efficiencies (EQE_max) of 25.7 and 29.2%, with λ_EL of 489 and 518 nm, and FWHMs of 53 and 69 nm, respectively. These EQE_max values are higher than those of other reported devices employing PCP-based D-A type emitters. This work demonstrates that the PCP moiety is not only a powerful building block to develop planar chiral emitters but one that is compatible with the fabrication of high efficiency devices.

A novel acceptor dimerization-based acceptor distortion strategy by taking advantage of the sterically encumbered acceptors with large volume and planar structure is proposed, through which the first NIR-II excitable and AIE-active SP with all of the phototheranostic features including NIR-II laser-triggered fluorescence-photoacoustic imaging and photodynamic-photothermal therapy is ingeniously reported.

Abstract

The development of semiconducting polymers (SPs) with simultaneous second near-infrared (NIR-II) absorption and multimodal phototheranostic functions is highly desired in the field of oncotherapy. Aggregation-induced emission luminogens (AIEgens) have been acknowledged to possess unique potential in integrating multiple diagnostic and therapeutic modalities into one organic molecule. Nevertheless, SPs are hard to achieve AIE activity due to their extended π-conjugated skeletons as well as the large and planar configuration of commonly-used electrophilic acceptor moieties. Herein, an ingenious acceptor dimerization-based acceptor distortion strategy is proposed in current work by taking advantage of the sterically encumbered acceptors with large and planar structure for the successful construction of AIE-active SPs. Through further finely adjusting the molecular donor–acceptor interaction strength, one of the obtained AIE-active SPs named SP3 bearing the highest intramolecular charge transfer effect presented desired NIR-II absorption and aggregation-induced NIR-II fluorescence emission, good reactive oxygen species production ability, as well as superior photothermal conversion performance. Accordingly, SP3 is selected to fabricate into nanoparticles and successfully applied in the NIR-II laser-triggered fluorescence-photoacoustic imaging-guided photodynamic-photothermal therapy of tumors. This study represents the first NIR-II excitable AIE-active SP, and offers a new perspective on designing advanced multimodal phototheranostic polymers for efficient treatment of malignant tumor.

A high-hole mobility pyrene-based organic semiconductor as an effective and universal hole transport layer additive is developed to achieve both high efficiency and stability in perovskite solar cells.

Abstract

Organic small molecules have been proven to be the most efficient and predominantly employed hole transport layers (HTLs) in perovskite solar cells (PSCs), the reliance of HTLs on additives like Li-TFSI has been unavoidable, particularly in terms of the well-known Spiro-OMeTAD. However, Li-TFSI aggregation in HTL results in the decreased performance and stability of PSCs with serious hysteresis. It is an urgent need to explore a universal strategy to solve Li-TFSI-induced issues. Herein, a pyrene-based organic semiconductor (PC) as an effective and universal additive for HTL application is developed. It is found that the introduction of PC can efficiently improve the hot carriers extraction/transfer and reduce the charge recombination in the device. Consequently, PSCs based on Spiro-OMeTAD+PC as a HTL exhibit an excellent PCE of 24.80% with a negligible hysteresis, much higher than the control device (22.14%). Additionally, the efficiency of the PC incorporated into another well-known X60 HTL-treated device is enhanced to 24.12% from the control device (22.04%), confirming its universal application in PSCs. Moreover, PC can effectively suppress the Li⁺ aggregation in HTL, and the unencapsulated PSCs exhibit high stability. The findings in this work provide an effective and universal avenue to construct highly efficient and stable PSCs.

Four thermally activated delayed fluorescence compounds based on planar di[2.2]paracyclophane are synthesized, and the asymmetric bridge-like configuration emitters are separated to (R/S)-C-DpCpN-Trz and (R/S)-C-DpCpCz-Trz enantiomers. These materials showed blue emissions with high photoluminescence quantum efficiencies, and the enantiomers exhibited symmetric circularly polarized luminescence spectra. The organic light-emitting diodes (OLEDs) based on four emitters exhibited high values of up to 19.5%, and the circularly polarized OLEDs with enantiomers displayed dissymmetry factors of up to 7.6 × 10⁻⁴.

Abstract

In this study, featuring di[2.2]paracyclophane (DpCp) amine derivatives as electron donors and 4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl (Trz) as the electron acceptor, four thermally activated delayed fluorescence (TADF) molecules are disclosed. The C ₂ symmetric molecules, DpCpN-Trz and DpCpCz-Trz, bearing a chair-like planar chiral di[2.2]paracyclophane moiety, are obtained as optically pure enantiomers (R/S)-C-DpCpN-Trz and (R/S)-C-DpCpCz-Trz. And the compounds B-DpCpN-Trz and B-DpCpCz-Trz with a bridge-like di[2.2]paracyclophane skeleton are meso-compounds, thus without optically activity. All emitters show blue emissions peaking from 464 to 485 nm, accompanied by high photoluminescence quantum efficiency (up to 93%). The enantiomers (R/S)-C-DpCpN-Trz and (R/S)-C-DpCpCz-Trz exhibit symmetric circularly polarized photoluminescence spectra with dissymmetry factors (|g _PL|) ranging from 3.8 × 10⁻⁴ to 6.7 × 10⁻⁴ in toluene and films. The organic light-emitting diodes (OLEDs) fabricated with these emitters achieve maximum external quantum efficiencies of up to 19.5%. Notably, the circularly polarized OLEDs (CP-OLEDs) with (R/S)-C-DpCpN-Trz and (R/S)-C-DpCpCz-Trz demonstrate |g _EL| factors of up to 7.6 × 10⁻⁴. This study demonstrates a feasible way to design TADF materials and enantiomers by incorporating DpCp derivatives for CP-OLEDs.

The photophysical properties and luminescence mechanism of 0D Cs₃Cu₂X₅ are systematically studied from the perspective of crystal structure and exciton property, employing both experimental and theoretical methods. Moreover, the excellent scintillation performance observed in Cs₃Cu₂X₅ is attributed to the presence of strongly confined excitons. Therefore, this study provides valuable insights into exploring the photophysical properties of 0D scintillators.

Abstract

Copper halides, a new class of attractive and potential scintillators, have attracted tremendous attention in X-ray imaging. However, the ambiguity surrounding their exciton properties and the unclear effect of crystal structure on their photophysical performance hinder an in-depth understanding of their luminescence mechanism and their further application in the X-ray imaging field. Herein, copper halide scintillators Cs₃Cu₂X₅ (X = I, Br, and Cl) with a 0D crystal structure is prepared, and their photophysical properties and luminescence mechanism are revealed using both theoretical calculation and experimental verification. The small exciton Bohr diameter together with the high exciton binding energy can cause Cs₃Cu₂X₅ to hold strongly confined excitons and lack quantum-size effects. The 0D Cs₃Cu₂X₅ materials exhibit a structural framework with a soft crystal lattice and Frenkel excitons with strong confinement effects, further resulting in a luminescence mechanism with self-trapped excitons. In particular, Cs₃Cu₂I₅ is demonstrated as an efficient scintillator with high radioluminescence efficiency and high spatial resolution of ≈106 µm in radiography, which is primarily attributed to strongly confined excitons to improve the radiative recombination probability of electron-hole pairs. Overall, this work provides a pathway for developing 0D scintillators with strongly confined excitons to improve X-ray imaging performance.

A series of phenothiazine 5,5-dioxide derivatives are synthesized, demonstrating that efficient intermolecular π–π interactions leading by folded conformation can promote the persistent RTP effect. PTZO-CF₃-3F with photo-activated RTP effect in a grinding state is utilized in the applications of anti-counterfeiting and optical logic gates, and the visual oxygen warning device is fabricated successfully with PTZO-CF₃-2F.

Abstract

Organic luminescent materials exhibiting persistent room temperature phosphorescence (RTP) have garnered considerable interest due to their versatile applications. However, the mechanism is still unclear, especially for the molecular structure-molecular arrangement-property relationship. Herein, six derivatives of phenothiazine 5,5-dioxide are synthesized, revealing their distinct RTP properties and the associated underlying mechanisms. Careful analyses of their single crystal structures, combined with initial theoretical calculations, indicate that the persistent RTP effect is facilitated by effective intermolecular π–π interactions in the solid state led by folded conformation. Specifically, PTZO-CF₃-3F exhibits distinctive photo-activated phosphorescence both in crystal and grinding state in response to the changes of molecular arrangement. Besides, a porous structure is found to be present in PTZO-CF₃-2F crystal, offering it great sensitivity to oxygen for both RTP intensity and lifetime. Accordingly, the visual oxygen warning device is fabricated successfully. Furthermore, PTZO-CF₃-3F with photo-activated RTP effect in a grinding state is successfully utilized in the applications of anti-counterfeiting and optical logic gates, expanding the scope of stimulus-responsive phosphorescence materials for broader applications.

A family of donor-acceptor TADF emitters containing a triphenylamine donor coupled to azaacene electron-acceptors shows selective and specific sensing of ZnCl₂ compared to 13 other Lewis acids. These same compounds are used as emitters in green-to-deep-red emissive OLEDs.

Abstract

Thermally activated delayed fluorescence (TADF) is an emission mechanism whereby both singlet and triplet excitons can be harvested to produce light. Significant attention is devoted to developing TADF materials for organic light-emitting diodes (OLEDs), while their use in other organic electronics applications such as sensors, has lagged. A family of TADF emitters, TPAPyAP, TPAPyBP, and TPAPyBPN containing a triphenylamine (TPA) donor and differing nitrogen-containing heterocyclic pyrazine-based acceptors is developed and systematically studied. Depending on the acceptor strength, these three compounds emit with photoluminescence maxima (λ_PL), of 516, 550, and 575 nm in toluene. Notably, all three compounds show a strong and selective spectral response to the presence of ZnCl₂, making them the first optical TADF sensors for this analyte. It is demonstrated that these three emitters can be used in vacuum-deposited OLEDs, which show moderate efficiencies. Of note, the device with TPAPyBPN in 2,8-bis(diphenyl-phoshporyl)-dibenzo[b,d]thiophene (PPT) host emits at 657 nm and shows a maximum external quantum efficiency (EQE_max) of 12.5%. This electroluminescence is significantly red-shifted yet shows comparable efficiency compared to a device fabricated in 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) host (λ_EL = 596 nm, EQE_max = 13.6%).

Novel lactam electron-acceptors are utilized to construct high-performance TADF molecules. The rigid molecular skeletons, ordered molecular arrangements, and precise control of excited states contribute to achieving ultra-high PLQYs (98%−99%), high horizontal dipole ratios (87%−91%), and rapid RISC (k_RISC ≈ 1.7 × 10⁶ s⁻¹) simultaneously. The optimized OLEDs attain high EQEs of up to 34.3%, accompanied by ultra-high luminances and small efficiency roll-offs.

Abstract

Thermally activated delayed fluorescence (TADF) materials that exhibit simultaneously high photoluminescence quantum yield (PLQY), rapid reverse intersystem crossing (RISC), and a high horizontal transition dipole ratio are highly desirable for realizing high-performance organic light-emitting diodes (OLEDs). However, achieving this goal remains a formidable challenge due to the stringent molecular design principles involved. Herein, three highly efficient TADF materials based on lactam-type electron-acceptors are reported. The inherent rigidity and planar structure of lactam units, along with the ordered molecular arrangement in solid states, contribute to the reduction of nonradiative decay and the high horizontal transition dipole ratio in the optimized TADF emitters. Moreover, through precise control of the alignment of the lowest excited states by adjusting the charge transfer strength, the rate constants for reverse intersystem crossing (k _RISC) are dramatically boosted. Consequently, the two optimized emitters exhibit outstanding merits of ultra-high PLQYs (98% and 99%), high horizontal transition dipole ratios (91% and 87%), and fast RISC (k _RISC ≈ 1.7 ×  10⁶ s⁻¹). Thanks to these merits, the doped OLEDs achieve excellent performance. The top-performing device achieve a maximum external quantum efficiency of 34.3%, a peak luminance of 57376 cd m^{− 2}, and small efficiency roll-off.

A new class of Zn-based metal coordination polymer glasses with ultra-long room temperature phosphorescence (RTP) is reported. The lifetime-adjustable and wavelength-tunable long-lived luminescence is achieved by halide engineering and dye doping and exhibits high-density information storage and dynamic anti-counterfeiting applications, providing future avenues for the design of new conceptual hybrid materials for photonic applications.

Abstract

Transparent glasses are ideal and robust hosts for a range of emission centers, while the simultaneous manipulation of the temporal and spectral characteristics of emission remains a tremendous challenge for inorganic glasses. Here, the development and functionalization of melt-quenched transparent coordinate polymer glasses with a tailorable ultralong room-temperature phosphorescence are demonstrated. Dynamic modulation of the phosphorescence is achieved by utilization of the high molecular rigidity and manipulation of the spin-orbital coupling effects within the glass systems. By introducing dye molecules into the glasses, Phosphorescence resonance energy transfer from the glass matrix to the dye molecules is exploited and controllable multicolor long-lived luminescence is demonstrated. Further design of the component and concentration of the encapsulated dyes allows for wavelength-tunable long-lived delayed fluorescence via an efficient delayed sensitization process, featuring a tunable emission spectrum covering a wide range from 520 to 630 nm. Leveraging the multiple spectral tuning channels of the hybrid glass, multi-mode optical information storage, and dynamic anti-counterfeiting applications are further demonstrated. This work provides a new hybrid material platform and design methodology for realizing lifetime-adjustable and wavelength-tunable long-lived luminescence, which can find wide applications in time-rsesolved information display, high-density information storage, and dynamic anti-counterfeiting.

The incorporation of aggregation-induced emission luminogen (AIEgen) into porous prussian blue (PB) nanocatalyzer significantly boosts fluorescence brightness and photodynamic therapy attributes as the molecular motion of AIEgen is highly restricted. PB can catalyze tumor-overexpressed H₂O₂ to generate oxygen to amplify photodynamic efficacy, and the near-infrared absorption also amplifies photoacoustic imaging and photothermal effect, rendering great promise for image-guided cancer immunotherapy.

Abstract

High-performance theranostic systems are of paramount importance for achieving precise image-guided cancer immunotherapy. Here, a novel nanoplatform is presented that integrates aggregation-induced emission luminogen (AIEgen) with prussian blue (PB) nanocatalyzer for robust cancer immunotherapy. The AIEgen with dimethylamine substitution demonstrates compelling near-infrared (NIR) light-induced photothermal conversion and photodynamic therapy (PDT) capabilities. By incorporating AIEgen into porous PBNPs, and further enveloped within M1 macrophage membrane, a tumor-specific theranostic nanoagent is constructed. This strategic integration effectively constrains the molecular motion of AIEgen, leading to amplified NIR-II fluorescence brightness and PDT attributes. Moreover, PBNPs can catalyze tumor-overexpressed H₂O₂ to generate oxygen to boost PDT efficacy, and PB's NIR absorption also intensifies photoacoustic imaging and photothermal effect. The integration of NIR-II fluorescence and photoacoustic imaging provides comprehensive information for photoimmunotherapy in orthotopic breast cancer-bearing mice. Leveraging its potent immunogenic cell death effect, the nanoagent not only significantly inhibits cancer growth, but also generates a whole-cell therapeutic cancer vaccine to protect mice from tumor rechallenge. In highly malignant post-surgery breast cancer models, the nanoagent enables both accurate identification of residual tumors and efficient inhibition of postoperative tumor recurrence and pulmonary metastasis. This study will offer valuable insights for creating highly efficacious and multifaceted photoimmunotherapy protocols.