Blue organic light-emitting diodes (OLEDs) employing multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters such as nu-DABNA exhibit narrowband emission and high color purity. However, their intrinsically slow reverse intersystem crossing (RISC) leads to triplet accumulation and accelerates device degradation. In this study, we provide insight into degradation behavior by coupling host engineering with electrical and chemical diagnostics. MADN-hosted devices exhibit minimal EQE roll-off and 2.47-fold longer lifetime than mCBP host counterparts, whereas mCBP yields a higher peak EQE but severe efficiency roll-off and faster degradation. Impedance spectroscopy reveals a pronounced low-frequency resistance increase exclusively in degraded mCBP devices, which is consistent with trap build-up near the EML region. Laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) provides direct chemical evidence that nu-DABNA-derived fragments nearly doubled, and carbazole-derived fragments increased 7.6-fold in mCBP devices, consistent with bond dissociation energy (BDE) predictions identifying weak bonds in the anionic and triplet states. Overall, these results suggest that host-dependent differences in triplet energy alignment, BDE, and exciton management contribute to the observed degradation behavior in the MADN- and mCBP-hosted blue MR-TADF OLEDs. They further indicate that LDI-TOF MS can serve as an effective tool for elucidating EML degradation chemistry at the molecular level.

Two benzofuropyridine-based n-type host materials incorporating dibenzofuran core, 4,6-bis(benzofuro[2,3-b] pyridin-3-yl) dibenzo [b, d] furan (BFPDB-1) and 4,6-bis(benzofuro[2,3-b] pyridin-6-yl) dibenzo [b, d] furandibenzo [b, d] furan (BFPDB-2), were designed to investigate the impact of positional isomerism on exciton management in OLEDs. Subtle relocation of the pyridine nitrogen significantly modulates molecular polarity, charge-transfer character, and emissive-layer morphology, as confirmed by theoretical and experimental analyses. While conventional phosphorescent devices exhibit comparable efficiencies, pronounced performance differences emerge in phosphor-sensitized fluorescence (PSF) OLEDs. The BFPDB-2-based PSF device achieves a maximum external quantum efficiency of 22% and retains 20.7% EQE at 10,000 cd m-2 . This suppressed roll-off is consistent with improved energy funneling and reduced short-range local association, as suggested by transient photoluminescence (TRPL) and molecular dynamics (MD) / radial distribution function (RDF) analyses, which are associated with the distinct physicochemical properties of BFPDB-2, including its larger dipole moment, improved charge-transport balance, and more spatially distributed host-guest arrangement. These findings suggest that precise heteroatom placement, which enables modulation of molecular polarity, is a promising design direction for improving host-guest interactions and achieving high-efficiency, low-roll-off PSF OLEDs.

ABSTRACT Achieving high Commission Internationale de L'Eclairage (CIE) y values in green emitters is essential for next‐generation display technologies. However, the number of green multiresonance thermally activated delayed fluorescence (MR‐TADF) emitters achieving pure emission with high CIEy values is still limited, hindering compliance with the Broadcast Service Television 2020 (BT.2020) standard. Here, we report a new MR‐TADF emitter , xy‐ BPhCz, rationally designed by modifying the well‐established blue DABNA core with phenylcarbazole, xylene, and t‐butyl substituents. These structural modifications extend the π‐framework, induce a red‐shift, while simultaneously suppressing molecular aggregation and isomer formation, ultimately giving ultrapure green emission. The newly designed xy‐ BPhCz exhibits a high photoluminescence quantum yield of 84.5%. An ultra‐narrow full width at half maximum (FWHM) of 16 nm in cyclohexane was recorded, corresponding to CIE coordinates of (0.194, 0.739) which is closely approaching the BT.2020 green standard. When implemented in a phosphorescence‐sensitized OLED, the device achieved an external quantum efficiency of 28.0%. Particularly, the TADF device showed a high CIEy of 0.714, with a small FWHM of 25.8 nm, underscoring its potential for next‐generation ultra‐high‐definition displays.

Molecular descriptors are central to the performance and interpretability of QSPR models, yet most existing fingerprints for organic electronics lack chemical relevance or interpretability. Here, we present the Organic Electronic Fingerprint (OEFP), a structure-based representation tailored for OLED and OPV materials. OEFP was constructed from a manually curated OLED dataset and publicly available OPV and chromophore datasets to ensure structural diversity. Synthetically accessible substructures were identified using fragmentation and ring decomposition methods, which capture the conjugated π-bonds crucial for organic electronic materials, and subsequently encoded as individual bits. In case studies of OPV HOMO energy prediction, OEFP achieved up to 13.7

In this study, we demonstrate intrinsically stretchable green phosphorescent light-emitting diodes (IS-PhOLEDs) utilizing small molecules, achieved through a mechanically compliant emissive layer. This layer is engineered by blending an elastomeric polymer with a nanocomposite host-dopant system of small molecules. Notably, the light-emitting layer preserves equidistant under 30% applied strain, ensuring stable operation of IS-PhOLEDs during deformation. The resulting IS-PhOLEDs exhibit a 6.0 turn-on voltage and achieve a maximum current efficiency and luminance of 15.12 cd A-1 and 14,881 cd m-2. This device maintains consistent brightness without degradation, even when subjected to 30% mechanical strain.

Solution-processed phosphorescent inverted organic light-emitting diodes (s-IOLEDs) have garnered significant attention due to their excellent stability and high performance. However, frequently used inorganic electron transport layers usually cause exciton dissociation at the emitting layer interface, leading to low device efficiency and severe efficiency roll-off. In this work, we designed a cross-linkable triazine-grafted electron transport copolymer (PPDPT-co-PBCB) with a high triplet energy (3.11 eV) to suppress this exciton dissociation. Balance between electron transport ability and cross-linkability was controlled by varying the ratios between PPDPT and PBCB (9:1 and 8:2), resulting in significantly improved device efficiency. Our s-IOLED incorporating PPDPT-co-PBCB (8:2) achieved a current efficiency of 59.85 cd A-1 and an external quantum efficiency (EQE) of 16.17% with a minimal efficiency roll-off (1.05%) at a luminance of 5000 cd/m2. Furthermore, estimations of the recombination zone width and interfacial mixing width revealed that the device with PPDPT-co-PBCB (8:2) featured a relatively broad recombination zone, a weak triplet-triplet annihilation, and a narrow interfacial mixing width, contributing to its enhanced efficiency and reduced roll-off.

This work reports the synthesis of a series of bipolar host polymers, specifically PPPIC-co-PPDPT (9:1), PPPIC-co-PPDPT (8:2), and PPPIC-co-PPDPT (7:3), which incorporate a hole-transporting unit, 7,7-dimethyl-5-phenyl-2-(4-vinylphenyl)-5,7-dihydroindeno[2,1-b]carbazole (PPIC), and an electron-transporting unit, 2,4-diphenyl-6-(4-vinylphenoxy)-1,3,5-triazine (PDPT). These polymers are meticulously designed to achieve efficient bipolar charge transport while exhibiting high triplet energy levels (T1), robust thermal stability, and smooth surface morphology. The tunability of the recombination zone position was achieved by adjusting the relative ratio of the hole and electron transport units in the emissive layer, leading to optimized charge balance and enhanced device performance. The maximum current efficiency of 40.71 cd/A and an EQE of 11.19% were achieved through a simple device structure. Overall, this study highlights the potential of these bipolar host materials for advancing the OLED technology by enabling superior charge transport and reducing efficiency roll-off.

This study introduces a strategic buffer layer approach to mitigate thermal-induced pixel shrinkage in top-emission organic light-emitting diodes (TEOLEDs), enhancing both thermal stability and efficiency. A new cathode composed of binary alloy from silver (Ag) and copper (Cu) is developed for their moderately high binding energy, improving film uniformity and boosting optical and electrical performance. High surface energy metals, aluminum (Al) and Cu are employed as buffer layers to regulate the growth mechanism, resulting in an exceptionally smooth cathode film. The optimal device is designed by incorporating a bilayer electron injection layer consisting of lithium fluoride (LiF) and ytterbium (Yb) along with the buffer layer. The TEOLEDs achieved an impressive efficiency of 178 cd A-1 and luminance of 247,000 cd m-2 while demonstrating superior thermal stability, with the absence of cathode shrinkage after 240 h at 85 degrees C. This stability is attributed to the suppression of thermal diffusion and aggregation, facilitated by the high surface energy buffer layer and innovative cathode compositions employed.

This study improves microcavity OLED performance by tackling viewing angle dependency and efficiency limitations. Integrating a nanoporous film (NPF) and index-matching gel resulted in a 26.36% enhancement in color stability and 14.2% increase in current efficiency. The NPF optimized angular light distribution, while the gel minimized internal reflection losses, enabling stable, high-efficiency OLEDs suitable for large-scale displays and advancing next-generation display technologies.

Top-emitting microcavity OLEDs (TEOLEDs) exhibit excellent color purity but suffer from severe angular color shifts. To overcome this, we introduce a nanotextured light modulation strategy using a nanoporous film (NPF) and an index-matched optically clear resin (OCR) for encapsulation. The nanotextured NPF enhances light outcoupling while suppressing cavity-induced angular dependence. As a result, the external quantum efficiency (EQE) is enhanced by 370

This study introduces a novel method to enhance top-emission OLED (TEOLED) performance using high-surface-energy metals, like aluminum, as buffer layers to control growth and achieve a smooth cathode surface. Optimization was further achieved by incorporating a bilayer electron injection layer with lithium fluoride (LiF), resulting in an 11.4% efficiency improvement and a 29% luminance increase.

The development of fully solution‐processed organic light‐emitting diodes (fs‐OLEDs) remains a significant challenge, primarily due to the lack of low‐temperature cross‐linkable materials for the emissive layer (EML). In this study, a novel material design strategy is reported for blue fs‐OLEDs, where a single framework can be adapted as a cross‐linked hole transport layer ( X‐HTL ), polymer hosts, or single‐component EML ( P27 , X‐P33 ), with minor structural modifications. Particularly, the single‐component EML ( X‐P33 ) demonstrates a remarkably low cross‐linking temperature ( T CL ) of 135 °C, showing no reduction in the photoluminescence quantum yield of the EML. A blue fs‐OLED comprising the single‐component EML ( X‐P33 ) achieves a comparable efficiency with the partial solution‐processed device, demonstrating its promised application. A rationally designed novel pyrene‐based blue emitting small molecule, 3,8‐DI‐DAP‐C7 , is additionally introduced. Employing this material as a blue dopant, a current efficiency of ≈4.7 cd A −1 and external quantum efficiency of 3.2% is achieved.

To achieve very high efficiency in solution-processed organic light emitting diodes (OLEDs), one promising and trailblazing approach is the utilization of the phosphor sensitized fluorescence (PSF) mechanism. In our study, we successfully apply this mechanism to fabricate highly efficient blue solution-processed device by introducing novel structured platinum (Pt) complex as a phosphorescent sensitizer. The significant spectral overlap between the sensitizer and final dopant (JF), with a JF value of 14.83 x 1014 nm4 M- 1 cm-1, enables high rates of energy transfer and results in a moderately high external quantum efficiency, with the device displaying (0.12, 0.12) color coordinates while achieving a notable 9.68 % external quantum efficiency. The system is particularly promising for designing OLEDs with sub-microsecond radiation decay times. Additionally, the PSF emitter exhibits ultrapure blue emission, with a narrow full-width half maximum of 16 nm from photoluminescence and 18 nm from electroluminescence. Moreover, the radial distributions of EML molecules at different annealing temperatures were investigated, showing the absence of molecular aggregation, ensuring a smooth surface for the solution device. These findings highlight the promising potential of employing the PSF mechanism along with a stable interfacial layer to achieve remarkable performance in solution-processed OLED devices.

To address poor operational stability of solution-processed organic light emitting diodes (s-OLEDs), a key limitation compared to vacuum-deposited device, the study proposes molecular design strategy that controls intramolecular rotational freedom for two indacene-based host materials: 5,5,8,8-tetramethyl-14-(4-(4-(triphenylsilyl)phenyl)quinazolin-2-yl)-8,14-dihydro-5H-indeno[1,2-b]indeno[2',1':4,5]thieno [3,2-g]indole (DITI-QSi) and 14-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-5,5,8,8-tetramethyl-8,14-dihydro-5H-indeno[1,2-b]indeno[2',1':4,5]thieno [3,2-g]indole (DITI-tDOBNA). The bulky tetraphenylsilyl group in DITI-QSi introduces rotational freedom to the quinazoline unit, increasing molecular flexibility and leading to severe molecular aggregation and a low photoluminescence quantum yield (PLQY). In contrast, the rigid DOBNA unit with steric hindrance from tert-butyl groups in (tDOBNA) in DITI-tDOBNA significantly suppresses such intramolecular rotation and aggregation, ensuring close host-emitter proximity and improving PLQY, which thereby enhances both F & ouml;rster and Dexter energy transfer processes. Additionally, an efficient electron-withdrawing effect of DOBNA helps to improve the charge balance within the emitting layer. A red phosphorescent s-OLED incorporating DITI-tDOBNA achieves a high current efficiency of 25.1 cd/A and an external quantum efficiency (EQE) of 18.6%, with minimal efficiency roll-off. Notably, the device demonstrates outstanding operational stability, with a half-lifetime (LT50) of 1400 h.