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1.
Small ; 20(16): e2309309, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38016075

RESUMO

As an essential component of future full-color displays, blue perovskite light-emitting diodes (PeLEDs) still lag far behind the red and green counterparts in the device performances. In the mainstream quasi-2D blue perovskite system, trap-mediated nonradiative loss, low energy transfer efficiency, and interface fluorescence quenching remain significant challenges. Herein, guanidinium thiocyanate (GASCN) and potassium cinnamate (PCA) are respectively introduced into the hole transport layer (HTL) and the perovskite precursor to achieve a dense and uniform perovskite thin film with greatly improved optoelectronic properties. Therefore, adequate GA+ acts as pre-nucleation sites on the HTL surface, regulating crystallization through strong hydrogen bonding with perovskite intermediates. The realized polydisperse domain distribution is conducive to cascade energy transfer, and the improved hole transport ability alleviates interface fluorescence quenching. In addition, the SCN- and CA- groups can form coordination bonds with the defects at the buried perovskite interface and grain boundaries, respectively, which effectively suppresses the detrimental nonradiative recombination. Benefitting from the comprehensive crystal regulation, blue PeLEDs featuring stable emission at 484 and 468 nm exhibit improved external quantum efficiencies of 11.5% and 4.3%, respectively.

2.
Small ; 20(26): e2311377, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38299746

RESUMO

Developing inventive approaches to control crystallization and suppress trap defects in perovskite films is crucial for achieving efficient perovskite photovoltaics. Here, a synchronous regulation strategy is developed that involves the infusion of a zwitterionic ionic liquid additive, pyrrolidinium thiocyanate (PySCN), into the perovskite precursor to optimize the subsequent crystallization and defects. PySCN modification not only orchestrates the crystallization process but also deftly addresses trap defects in perovskite films. Within this, SCN- compensates for positively charged defects, while Py+ plays the role of passivating negatively charged defects. Based on the vacuum flash evaporation without anti-solvent, the air-processed perovskite solar cells (PSCs) with PySCN modification can achieve an extraordinary champion efficiency of 22.46% (0.1 cm2) and 21.15% (1.0 cm2) with exceptional stability surpassing 1200 h. Further, the self-powered photodetector goes above and beyond, showcasing an ultra-low dark current of 2.13 × 10-10 A·cm-2, a specific detection rate of 6.12 × 1013 Jones, and an expansive linear dynamic range reaching an astonishing 122.49 dB. PySCN modification not only signifies high efficiency but also ushers in a new era for crystallization regulation, promising a transformative impact on the optoelectronic performance of perovskite-based devices.

3.
Small ; : e2401256, 2024 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-38752227

RESUMO

Nickel oxide (NiOx) is a promising hole transport layer (HTL) to fabricate efficient and large-scale inverted perovskite solar cells (PSCs) due to its low cost and superior chemical stability. However, inverted PSCs based on NiOx are still lagging behind that of other HTL because of the poor quality of buried interface contact. Herein, a bidentate ligand, 4,6-bis (diphenylphosphino) phenoxazine (2DPP), is used to regulate the NiOx surface and perovskite buried interface. The diphosphine Lewis base in the 2DPP molecule can coordinate both with NiOx and lead ions at NiOx/perovskite interface, leading to high-quality perovskite films with minimized defects. It is found that the inverted PSCs with 2DPP-modified buried interface exhibit double advantages of being both fast charge extraction and reduced nonradiative recombination, which is a combination of multiple factors including favorable energetic alignment, improved interface contact and strong binding between NiOx/2DPP and perovskite. The optimal PSC based on 2DPP modification yields a champion power conversion efficiency (PCE) of 21.9%. The unencapsulated PSC maintains above 75% of its initial PCE in the air with a relative humidity (RH) of 30-40% for 1000 h.

4.
Angew Chem Int Ed Engl ; 63(7): e202319730, 2024 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-38168882

RESUMO

Quasi-two-dimensional (quasi-2D) perovskites are emerging as efficient emitters in blue perovskite light-emitting diodes (PeLEDs), while the imbalanced crystallization of the halide-mixed system limits further improvements in device performance. The rapid crystallization caused by Cl doping produces massive defects at the interface, leading to aggravated non-radiative recombination. Meanwhile, unmanageable perovskite crystallization is prone to facilitate the formation of nonuniform low-dimensional phases, which results in energy loss during the exciton transfer process. Here, we propose a multifunctional interface engineering for nucleation and phase regulation by incorporating the zwitterionic additive potassium sulfamate into the hole transport layer. By using potassium ions (K+ ) as heterogeneous nucleation seeds, finely controlled growth of interfacial K+ -guided grains is achieved. The sulfamate ions can simultaneously regulate the phase distribution and passivate defects through coordination interactions with undercoordinated lead atoms. Consequently, such synergistic effect constructs quasi-2D blue perovskite films with smooth energy landscape and reduced trap states, leading to pure-blue PeLEDs with a maximum external quantum efficiency (EQE) of 17.32 %, spectrally stable emission at 478 nm and the prolonged operational lifetime. This work provides a unique guide to comprehensively regulate the halide-mixed blue perovskite crystallization by manipulating the characteristics of grain-growth substrate.

5.
Small ; 19(24): e2207817, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36919945

RESUMO

Both the uncoordinated Pb2+ and excess PbI2 in perovskite film will create defects and perturb carrier collection, thus leading to the open-circuit voltage (VOC ) loss and inducing rapid performance degradation of perovskite solar cells (PSCs). Herein, an additive of 3-aminothiophene-2-carboxamide (3-AzTca) that contains amide and amino and features a large molecular size is introduced to improve the quality of perovskite film. The interplay of size effect and adequate bonding strength between 3-AzTca and uncoordinated Pb2+ regulates the mineralization of PbI2 and generates low-dimensional PbI2 phase, thereby boosting the crystallization of perovskite. The decreased defect states result in suppressed nonradiative recombination and reduced VOC loss. The power conversion efficiency (PCE) of modified PSC is improved to 22.79% with a high VOC of 1.22 V. Moreover, the decomposition of PbI2 and perovskite films is also retarded, yielding enhanced device stability. This study provides an effective method to minimize the concentration of uncoordinated Pb2+ and improve the PCE and stability of PSCs.

6.
Phys Chem Chem Phys ; 24(21): 13210-13216, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35593393

RESUMO

The booming growth of all inorganic cesium lead halide perovskites in optoelectronic applications has prompted extensive research interest in the fabrication of ordered nanostructures or microarrays for enhanced device performances. However, the high cost and complexity of commercial lithographic approaches impede the facile fabrication of perovskite microarrays. Herein, CsPbBr3 microarrays with tunable periodicities have been fabricated using a self-assembled polystyrene nanosphere template and a co-evaporation method. The periodicity of CsPbBr3 microarrays is precisely manipulated by simply modifying the size of polystyrene nanospheres. These microarrays are beneficial for light harvesting, leading to better light absorption ability and prolonged photoinduced carrier lifetime. The longest average carrier lifetime of 58.3 ns is obtained for CsPbBr3 microarrays with a periodicity of 1.0 µm. More importantly, the periodic structures of CsPbBr3 microarrays result in a tunable density of emitter tips in field emission devices. Compared to compact CsPbBr3 films, a 68.2% decrease of the turn-on field is observed for CsPbBr3 microarrays when the periodicity is 150 nm. The higher density of emitter tips leads to larger local field enhancement, and hence the largest field enhancement factor of 3346.6. Finally, a good emission current stability for CsPbBr3 microarray-based field emission devices has been demonstrated.

7.
Angew Chem Int Ed Engl ; 61(49): e202213823, 2022 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-36206365

RESUMO

Organic materials featuring intramolecular through-space charge transfer (TSCT) excited states are advantageous for efficient thermally activated delayed fluorescence (TADF), although the realization of multiple TSCT systems remains challenging. Herein, a rigid molecule with a three-dimensional dislocated sandwich acceptor-donor-acceptor configuration has been developed by a linking biphenazine (2PXZ) donor and 2,4,6-triphenyl-1,3,5-triazine (TRZ) acceptor through the twin-locking of two spiro-fluorene bridges. The twin-locking construction with multiple TSCT effects suppresses the intramolecular rotations of various segments in 2PXZ-2TRZ, leading to a small singlet-triplet energy difference, a fast reverse intersystem crossing process, and high photoluminescence quantum yield. This material simultaneously possesses the capabilities of TADF and aggregation-induced emission. The device employing 2PXZ-2TRZ as a dopant displays an optimal external quantum efficiency of 27.1 % and a low efficiency roll-off.

8.
Zhongguo Dang Dai Er Ke Za Zhi ; 22(5): 419-424, 2020 May.
Artigo em Zh | MEDLINE | ID: mdl-32434634

RESUMO

OBJECTIVE: To study the clinical features of coronavirus disease 2019 (COVID-19) in children aged <18 years. METHODS: A retrospective analysis was performed from the medical data of 23 children, aged from 3 months to 17 years and 8 months, who were diagnosed with COVID-19 in Jiangxi, China from January 21 to February 29, 2020. RESULTS: Of the 23 children with COVID-19, 17 had family aggregation. Three children (13%) had asymptomatic infection, 6 (26%) had mild type, and 14 (61%) had common type. Among these 23 children, 16 (70%) had fever, 11 (48%) had cough, 8 (35%) had fever and cough, and 8 (35%) had wet rales in the lungs. The period from disease onset or the first nucleic acid-positive detection of SARS-CoV-2 to the virus nucleic acid negative conversion was 6-24 days (median 12 days). Of the 23 children, 3 had a reduction in total leukocyte count, 2 had a reduction in lymphocytes, 2 had an increase in C-reactive protein, and 2 had an increase in D-dimer. Abnormal pulmonary CT findings were observed in 12 children, among whom 9 had patchy ground-glass opacities in both lungs. All 23 children received antiviral therapy and were recovered. CONCLUSIONS: COVID-19 in children aged <18 years often occurs with family aggregation, with no specific clinical manifestation and laboratory examination results. Most of these children have mild symptoms and a good prognosis. Epidemiological history is of particular importance in the diagnosis of COVID-19 in children aged <18 years.


Assuntos
Betacoronavirus , Infecções por Coronavirus , Pandemias , Pneumonia Viral , Adolescente , COVID-19 , Criança , Pré-Escolar , China , Humanos , Lactente , Estudos Retrospectivos , SARS-CoV-2
9.
J Neurosci ; 37(30): 7096-7110, 2017 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-28630256

RESUMO

Extinction of aversive memories has been a major concern in neuropsychiatric disorders, such as anxiety disorders and drug addiction. However, the mechanisms underlying extinction of aversive memories are not fully understood. Here, we report that extinction of conditioned place aversion (CPA) to naloxone-precipitated opiate withdrawal in male rats activates Rho GTPase Rac1 in the ventromedial prefrontal cortex (vmPFC) in a BDNF-dependent manner, which determines GABAA receptor (GABAAR) endocytosis via triggering synaptic translocation of activity-regulated cytoskeleton-associated protein (Arc) through facilitating actin polymerization. Active Rac1 is essential and sufficient for GABAAR endocytosis and CPA extinction. Knockdown of Rac1 expression within the vmPFC of rats using Rac1-shRNA suppressed GABAAR endocytosis and CPA extinction, whereas expression of a constitutively active form of Rac1 accelerated GABAAR endocytosis and CPA extinction. The crucial role of GABAAR endocytosis in the LTP induction and CPA extinction is evinced by the findings that blockade of GABAAR endocytosis by a dynamin function-blocking peptide (Myr-P4) abolishes LTP induction and CPA extinction. Thus, the present study provides first evidence that Rac1-dependent GABAAR endocytosis plays a crucial role in extinction of aversive memories and reveals the sequence of molecular events that contribute to learning experience modulation of synaptic GABAAR endocytosis.SIGNIFICANCE STATEMENT This study reveals that Rac1-dependent GABAAR endocytosis plays a crucial role in extinction of aversive memories associated with drug withdrawal and identifies Arc as a downstream effector of Rac1 regulations of synaptic plasticity as well as learning and memory, thereby suggesting therapeutic targets to promote extinction of the unwanted memories.


Assuntos
Aprendizagem da Esquiva/fisiologia , Endocitose/fisiologia , Extinção Psicológica/fisiologia , Memória/fisiologia , Córtex Pré-Frontal/fisiologia , Receptores de GABA-A/metabolismo , Proteínas rac1 de Ligação ao GTP/metabolismo , Animais , Masculino , Rememoração Mental/fisiologia , Ratos , Ratos Sprague-Dawley , Repressão Psicológica
10.
Immunology ; 154(1): 144-155, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29211299

RESUMO

A recent study indicated that Lectin-type oxidized LDL receptor-1 (LOX-1) was a distinct surface marker for human polymorphisms myeloid-derived suppressor cells (PMN-MDSC). The present study was aimed to investigate the existence LOX-1 PMN-MDSC in hepatocellular carcinoma (HCC) patients. One hundred and twenty-seven HCC patients, 10 patients with mild active chronic hepatitis B, 10 liver cirrhosis due to hepatitis B, 10 liver dysplastic node with hepatitis B and 50 health control were included. LOX-1+  CD15+ PMN-MDSC were significantly elevated in HCC patients compared with healthy control and patients with benign diseases. LOX-1+  CD15+ PMN-MDSC in circulation were positively associated with those in HCC tissues. LOX-1+  CD15+ PMN-MDSCs significantly reduced proliferation and IFN-γ production of T cells with a dosage dependent manner with LOX-1-  CD15+ PMNs reached negative results. The suppression on T cell proliferation and IFN-γ production was reversed by ROS inhibitor and Arginase inhibitor. ROS level and activity of arginase of LOX-1 + CD15+ PMN were higher in LOX-1+  CD15+ PMN-MDSCs than LOX-1-  CD15+ PMNs, as well as the expression of the NADPH oxidase NOX2 and arginase I. RNA sequence revealed that LOX-1+ CD15+ PMN-MDSCs displayed significantly higher expression of spliced X-box -binding protein 1 (sXBP1), an endoplasmic reticulum (ER) stress marker. ER stress inducer induced LOX-1 expression and suppressive function for CD15+ PMN from health donor. For HCC patients, LOX-1+  CD15+ PMN-MDSCs were positively related to overall survival. Above all, LOX-1+  CD15+ PMN-MDSC were elevated in HCC patients and suppressed T cell proliferation through ROS/Arg I pathway induced by ER stress. They presented positive association with the prognosis of HCC patients.


Assuntos
Carcinoma Hepatocelular/metabolismo , Estresse do Retículo Endoplasmático , Fucosiltransferases/metabolismo , Antígenos CD15/metabolismo , Neoplasias Hepáticas/metabolismo , Células Supressoras Mieloides/metabolismo , Receptores Depuradores Classe E/metabolismo , Arginase/metabolismo , Carcinoma Hepatocelular/imunologia , Carcinoma Hepatocelular/patologia , Estudos de Casos e Controles , Proliferação de Células , Células Cultivadas , Técnicas de Cocultura , Humanos , Interferons/metabolismo , Neoplasias Hepáticas/imunologia , Neoplasias Hepáticas/patologia , Ativação Linfocitária , Células Supressoras Mieloides/imunologia , Células Supressoras Mieloides/patologia , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Linfócitos T/imunologia , Linfócitos T/metabolismo
11.
Cell Physiol Biochem ; 48(1): 317-327, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30016765

RESUMO

BACKGROUND/AIMS: Patient selection is critically important in improving the outcomes of liver transplantation for hepatocellular carcinoma. The aim of the current study was to identify biochemical measures that could affect patient prognosis after liver transplantation. METHODS: A total of 119 patients receiving liver transplantation for hepatocellular carcinoma were used to construct a model for predicting recurrence. The results were validated using an independent sample of 109 patients from independent hospitals. All subjects in both cohorts met the Hangzhou criteria. RESULTS: Analysis of the discovery cohort revealed an association of recurrence with preoperative fibrinogen and AFP levels. A mathematical model was developed for predicting probability of recurrence within 5 years: Y = logit(P) = -4.595 + 0.824 ×fibrinogen concentration (g/L) + 0.641 × AFP score (1 for AFP<=20ng/ml, 2 for 20 400ng/ml). At a cutoff score of -0.85, the area under the curve (AUC) was 0.819 in predicting recurrence (vs. 0.655 when using the Milan criteria). In the validation cohort, this model had reasonable performance in predicting 5-year overall survival (68.8% vs. 28.1% in using the -0.85 cutoff, p< 0.001) and disease-free survival (65.7% vs. 25.9%, p< 0.001). The sensitivity and specificity were 77.0% and 62.5%, respectively. The AUC of this newly developed model was similar to that with the Milan criteria (0.698 vs. 0.678). Surprisingly, the DFS in patients with score <= -0.85 under this model but not meeting the Milan criteria was similar to that in patients meeting the Milan criteria (53.8% vs. 60.0%, p=0.380). CONCLUSIONS: Preoperative AFP and fibrinogen are useful in predicting recurrence of hepatocellular carcinoma after liver transplantation.


Assuntos
Carcinoma Hepatocelular/terapia , Fibrinogênio/análise , Neoplasias Hepáticas/terapia , Transplante de Fígado , Modelos Teóricos , alfa-Fetoproteínas/análise , Área Sob a Curva , Carcinoma Hepatocelular/mortalidade , Intervalo Livre de Doença , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Período Pré-Operatório , Curva ROC , Estudos Retrospectivos , Fatores de Risco
12.
Opt Express ; 25(14): 15662-15675, 2017 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-28789080

RESUMO

It is challenging in realizing high-performance transparent organic light-emitting diodes (OLEDs) with symmetrical light emission to both sides. Herein, an efficient transparent OLED with highly balanced white emission to both sides is demonstrated by integrating quasi-periodic nanostructures into the organic emitter and the metal-dielectric composite top electrode, which can simultaneously suppressing waveguide and surface plasmonic loss. The power efficiency and external quantum efficiency are raised to 83.5 lm W-1 and 38.8%, respectively, along with a bi-directional luminance ratio of 1.26. The proposed scheme provides a facile route for extending application scope of transparent OLEDs for future transparent displays and lightings.

13.
Opt Express ; 24(6): A674-81, 2016 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-27136885

RESUMO

Flexible organic light-emitting diodes (OLEDs) are emerging as a leading technology for rollable and foldable display applications. For the development of high-performance flexible OLEDs on plastic substrate, we report a transparent nanocomposite electrode with superior mechanical, electrical, and optical properties, which is realized by integrating the nanoimprinted quasi-random photonic structures into the ultrathin metal/dielectric stack to collectively optimize the electrical conduction and light outcoupling capabilities. The resulting flexible OLEDs with green emission yield the enhanced device efficiency, reaching the maximum external quantum efficiency of 43.7% and luminous efficiency of 154.9 cd/A, respectively.

14.
Phys Chem Chem Phys ; 18(5): 4045-50, 2016 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-26775613

RESUMO

Mechanisms of charge transport between the interconnector and its neighboring layers in tandem organic photovoltaic cells have been systematically investigated by studying electronic properties of the involving interfaces with photoelectron spectroscopies and performance of the corresponding devices. The results show that charge recombination occurs at HATCN and its neighboring hole transport layers which can be deposited at low temperature. The hole transport layer plays an equal role to the interconnector itself. These insights provide guidance for the identification of new materials and the device architecture for high performance devices.

15.
World J Gastroenterol ; 30(14): 1958-1962, 2024 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-38681123

RESUMO

According to the report from the Chinese Center for Disease Control and Prevention, the prevalence of human immunodeficiency virus (HIV) infection exceeded 1.2 million individuals by the year 2022, with an annual increase of about 80000 cases. The overall prevalence of hepatitis B surface antigen among individuals co-infected with HIV reached 13.7%, almost twice the rate of the general population in China. In addition to the well-documented susceptibility to opportunistic infections and new malignancies, HIV infected patients frequently experience liver-related organ damage, with the liver and kidneys being the most commonly affected. This often leads to the development of end-stage liver and kidney diseases. Therefore, organ transplantation has emerged as an important part of active treatment for HIV infected patients. However, the curative effect is not satisfactory. HIV infection has been considered a contraindication for organ transplantation. Until the emergence of highly active anti-retroviral therapy in 1996, the once intractable replication of retrovirus was effectively inhibited. With prolonged survival, the failure of important organs has become the main cause of death among HIV patients. Therefore, transplant centers worldwide have resumed exploration of organ transplantation for HIV-infected individuals and reached a positive conclusion. This study provides an overview of the current landscape of HIV-positive patients receiving liver transplantation (LT) in mainland China. To date, our transplant center has conducted LT for eight end-stage liver disease patients co-infected with HIV, and all but one, who died two months postoperatively due to sepsis and progressive multi-organ failure, have survived. Comparative analysis with hepatitis B virus-infected patients during the same period revealed no statistically significant differences in acute rejection reactions, cytomegalovirus infection, bacteremia, pulmonary infections, acute kidney injury, new-onset cancers, or vascular and biliary complications.


Assuntos
Infecções por HIV , Transplante de Fígado , Humanos , Terapia Antirretroviral de Alta Atividade , China/epidemiologia , Coinfecção , Doença Hepática Terminal/cirurgia , Doença Hepática Terminal/mortalidade , Doença Hepática Terminal/diagnóstico , Doença Hepática Terminal/virologia , Hepatite B/complicações , Hepatite B/epidemiologia , Hepatite B/virologia , Infecções por HIV/complicações , Infecções por HIV/epidemiologia , Infecções por HIV/terapia , Transplante de Fígado/efeitos adversos , Transplante de Fígado/métodos , Prevalência , Resultado do Tratamento
16.
ACS Nano ; 18(5): 4570-4578, 2024 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-38277481

RESUMO

3D perovskites with low energy disorder and high ambipolar charge mobility represent a promising solution for efficient and bright light-emitting diodes. However, the challenges of regulating the nanocrystal size to trigger the quantum confinement effect and control the surface trap states to reduce charge loss hinder the applications of 3D perovskites in blue perovskite light-emitting diodes (PeLEDs). In this study, we present a top-down exfoliation method to obtain blue 3D perovskite films with clipped nanocrystals and tunable bandgaps by employing methyl cyanide (MeCN) for post-treatment. In this method, the MeCN solvent exfoliates the surface components of the 3D perovskite grains through a partial dissolution process. Moreover, the dissolved precursor can be further utilized to construct an ingenious 2D/3D heterostructure by incorporating an organic spacer into the MeCN solvent, contributing to efficient defect passivation and improved energy transfer. Consequently, efficient PeLEDs featuring ultrapure blue emission at 478 nm achieve a record external quantum efficiency of 12.3% among their 3D counterparts. This work emphasizes the significance of inducing the quantum confinement effect in 3D perovskites for efficient blue PeLEDs and provides a viable scheme for the in situ regulation of perovskite crystals.

17.
Mater Horiz ; 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38842068

RESUMO

Intramolecular exciplex systems featuring thermally activated delayed fluorescence (TADF) have garnered significant attention in the realm of organic light-emitting diodes (OLEDs). Nonetheless, the occurrence of organic sandwich intramolecular exciplexes remains rare due to structural limitations and synthetic challenges. Herein, we present a novel rigid acceptor-donor-acceptor (A-D-A) sandwich complex, dSFQP, characterized by two sp3 C-locking moieties. This compound exhibits TADF characteristics facilitated by a multiple through-space charge-transfer process. X-ray crystallographic analysis confirms the distinctive sandwich configuration. The parallel spatial arrangement and minimized A-D-A configuration enhance electronic interactions, resulting in a high photoluminescence quantum yield, rapid reverse intersystem crossing rate, and sluggish nonradiative decay rate. OLEDs employing dSFQP as the dopant achieve a maximum external quantum efficiency (EQE) of 28.5% with a low efficiency roll-off of merely 2.8% at 1000 cd m-2. Even at a high brightness of 10 000 cd m-2, the EQE remains notably high at 17.5%. Our current results provide an effective way to further innovate the design of new organic charge-transfer complexes.

18.
Chem Sci ; 15(13): 4790-4796, 2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38550683

RESUMO

Deep-blue organic light-emitting diodes (OLEDs) with narrow emission spectra and high efficiency, meeting the Rec.2020 standard, hold significant promise in the realm of 4K/8K ultrahigh-definition displays. However, the development of light-emitting materials exhibiting both narrowband emission and high efficiency, particularly in the realm of deep-blue thermally activated delayed fluorescence (TADF), confronts substantial challenges. Herein, a novel deep-blue TADF emitter, named BOC-PSi, was designed by integrating a rigid B-heterotriangulene acceptor (A) with a rigid phenazasiline donor (D). The replacement of a sp3 carbon atom with a sp3 silicon atom in the D moiety helps to restrict the low-frequency bending vibration throughout the entire D-A molecular backbone, while concurrently accelerating the multi-channel reverse intersystem crossing (RISC) processes. Notably, OLEDs using the BOC-PSi emitter exhibit exceptional performance, with a high maximum external quantum efficiency (EQEmax) approaching 20%, and a superior color purity closely aligning with the Rec.2020 blue standard.

19.
ACS Appl Mater Interfaces ; 16(13): 16563-16572, 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38507218

RESUMO

In account of the energy gap law, the development of efficient narrow-band gap thermally activated delayed fluorescence (TADF) materials remains a major challenge for the application of organic light-emitting diodes (OLEDs). The orange-red TADF materials are commonly designed with either large π-conjugated systems or strong intramolecular donor-acceptor (D-A) interactions for red-shift emission and small singlet-triplet energy gap (ΔEST). There are rare reports on the simultaneous incorporation of these two strategies on the same material systems. Herein, two orange-red emitters named 1P2D-BP and 2P2D-DQ have been designed by extending the conjugation degree of the center acceptor DQ and increasing the number distribution of the peripheral donor PXZ units, respectively. The emission peak of 1P2D-BP is red-shifted to 615 nm compared to 580 nm for 2P2D-DQ, revealing the pronounced effect of the conjugation extension on the emission band gap. In addition, the distorted molecular structure yields a small ΔEST of 0.02 eV, favoring the acquisition of a high exciton utilization through an efficient reverse intersystem crossing process. As a result, orange-red OLEDs with both 1P2D-BP and 2P2D-DQ have achieved an external quantum efficiency (EQE) of more than 17%. In addition, the efficient white OLED based on 1P2D-BP is realized through precise exciton assignment and energy transport modulation, showing an EQE of 23.6% and a color rendering index of 82. The present work provides an important reference for the design of high-efficiency narrow-band gap materials in the field of solid-state lighting.

20.
Nanoscale ; 15(6): 2798-2805, 2023 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-36662239

RESUMO

The operational stability of reduced-dimensional metal halide perovskites (RD-MHPs) lags far behind the practical requirements for future high-definition displays. Thereinto, the electron durability of RD-MHPs plays a critical role in stable LEDs during continuous operation, however, it still lacks adequate research and a deep understanding. Herein, the electron durability and deterioration mechanism of phenethylammonium (PEA+)-modified RD-MHPs are systematically conducted through an in situ photoelectron spectroscopy technique by implementing tunable electron-beam radiation to simulate device operation. The formation of detrimental metallic lead (Pb0) caused by the reduction of lead ions (Pb2+) is observed along with the decomposition of PEA+ under electron-beam radiation, thereby changing the photophysical properties of PEA+-doped RD-MHPs. These results provide deep insight into the process of how injected electrons affect the performance of PEA+-doped perovskite LEDs, which may also provide potential guidance for designing robust and effective organic spacers for RD-MHPs.

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