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1.
Nature ; 624(7991): 289-294, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37871614

RESUMO

Inverted perovskite solar cells (PSCs) promise enhanced operating stability compared to their normal-structure counterparts1-3. To improve efficiency further, it is crucial to combine effective light management with low interfacial losses4,5. Here we develop a conformal self-assembled monolayer (SAM) as the hole-selective contact on light-managing textured substrates. Molecular dynamics simulations indicate that cluster formation during phosphonic acid adsorption leads to incomplete SAM coverage. We devise a co-adsorbent strategy that disassembles high-order clusters, thus homogenizing the distribution of phosphonic acid molecules, and thereby minimizing interfacial recombination and improving electronic structures. We report a laboratory-measured power conversion efficiency (PCE) of 25.3% and a certified quasi-steady-state PCE of 24.8% for inverted PSCs, with a photocurrent approaching 95% of the Shockley-Queisser maximum. An encapsulated device having a PCE of 24.6% at room temperature retains 95% of its peak performance when stressed at 65 °C and 50% relative humidity following more than 1,000 h of maximum power point tracking under 1 sun illumination. This represents one of the most stable PSCs subjected to accelerated ageing: achieved with a PCE surpassing 24%. The engineering of phosphonic acid adsorption on textured substrates offers a promising avenue for efficient and stable PSCs. It is also anticipated to benefit other optoelectronic devices that require light management.

2.
Nature ; 618(7963): 74-79, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36977463

RESUMO

The tunable bandgaps and facile fabrication of perovskites make them attractive for multi-junction photovoltaics1,2. However, light-induced phase segregation limits their efficiency and stability3-5: this occurs in wide-bandgap (>1.65 electron volts) iodide/bromide mixed perovskite absorbers, and becomes even more acute in the top cells of triple-junction solar photovoltaics that require a fully 2.0-electron-volt bandgap absorber2,6. Here we report that lattice distortion in iodide/bromide mixed perovskites is correlated with the suppression of phase segregation, generating an increased ion-migration energy barrier arising from the decreased average interatomic distance between the A-site cation and iodide. Using an approximately 2.0-electron-volt rubidium/caesium mixed-cation inorganic perovskite with large lattice distortion in the top subcell, we fabricated all-perovskite triple-junction solar cells and achieved an efficiency of 24.3 per cent (23.3 per cent certified quasi-steady-state efficiency) with an open-circuit voltage of 3.21 volts. This is, to our knowledge, the first reported certified efficiency for perovskite-based triple-junction solar cells. The triple-junction devices retain 80 per cent of their initial efficiency following 420 hours of operation at the maximum power point.

3.
Nature ; 603(7899): 73-78, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35038717

RESUMO

All-perovskite tandem solar cells hold the promise of surpassing the efficiency limits of single-junction solar cells1-3; however, until now, the best-performing all-perovskite tandem solar cells have exhibited lower certified efficiency than have single-junction perovskite solar cells4,5. A thick mixed Pb-Sn narrow-bandgap subcell is needed to achieve high photocurrent density in tandem solar cells6, yet this is challenging owing to the short carrier diffusion length within Pb-Sn perovskites. Here we develop ammonium-cation-passivated Pb-Sn perovskites with long diffusion lengths, enabling subcells that have an absorber thickness of approximately 1.2 µm. Molecular dynamics simulations indicate that widely used phenethylammonium cations are only partially adsorbed on the surface defective sites at perovskite crystallization temperatures. The passivator adsorption is predicted to be enhanced using 4-trifluoromethyl-phenylammonium (CF3-PA), which exhibits a stronger perovskite surface-passivator interaction than does phenethylammonium. By adding a small amount of CF3-PA into the precursor solution, we increase the carrier diffusion length within Pb-Sn perovskites twofold, to over 5 µm, and increase the efficiency of Pb-Sn perovskite solar cells to over 22%. We report a certified efficiency of 26.4% in all-perovskite tandem solar cells, which exceeds that of the best-performing single-junction perovskite solar cells. Encapsulated tandem devices retain more than 90% of their initial performance after 600 h of operation at the maximum power point under 1 Sun illumination in ambient conditions.

4.
Physiol Genomics ; 56(2): 158-166, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38047310

RESUMO

PANoptosis is an inflammatory programmed cell death (PCD) regulated by multifaceted PANoptosome complexes with major features of pyroptosis, apoptosis, and/or necroptosis that cannot be accounted for by any of these PCD pathways alone. The aim of this study was to investigate the role of PANoptosis on the occurrence and development of abdominal aortic aneurysm (AAA). Clinical samples of patients with AAA, angiotensin II (ANG II)-induced AAA mouse model, and ANG II-induced vascular smooth muscle cells (VSMCs) in vitro model were used for investigation on PANoptosis features. The expressions of ZBP1, AIM2, and other markers related to pyroptosis, apoptosis, and necroptosis elevated obviously in aortic wall tissues of patients with AAA, mice with AAA, and ANG II-treated VSMCs. ANG II treatment increased inflammatory cytokines levels in VSMCs. The stimulation of tumor necrosis factor-α (TNF-α) or interleukin-1ß (IL-1ß) alone promoted VSMCs death, and the effect of TNF-α combined with IL-1ß is more obvious. The expressions of ZBP1, AIM2, and related markers of pyroptosis, apoptosis, and necroptosis were increased by TNF-α and IL-1ß combined treatment. Inhibition of TNF-α and/or IL-1ß in mice with AAA improved the AAA pathology, reduced the loss of VSMCs, decreased the expression of ZBP1 and AIM2, and markers associated with pyroptosis, apoptosis, and necroptosis. PANoptosis features were observed in aortic wall tissues of patients with AAA, mice with AAA, and ANG II-treated VSMCs. The inhibition of TNF-α and IL-1ß can alleviate PANoptosis in mice with AAA, which provides a new strategy for the prevention and treatment of AAA.NEW & NOTEWORTHY Early detection, diagnosis, and treatment are very important to improve the quality of life and prognosis of patients with abdominal aortic aneurysm (AAA). Based on the findings of apoptosis, necroptosis, and pyroptosis (PANoptosis) in AAA clinical samples, this study further explored the molecular mechanism in vivo and in vitro. Specifically, inhibition of tumor necrosis factor-α and interleukin-1ß can reduce PANoptosis in vascular smooth muscle cell and thus alleviate the process of AAA.


Assuntos
Aneurisma da Aorta Abdominal , Fator de Necrose Tumoral alfa , Humanos , Camundongos , Animais , Fator de Necrose Tumoral alfa/metabolismo , Interleucina-1beta/metabolismo , Músculo Liso Vascular/metabolismo , Qualidade de Vida , Aneurisma da Aorta Abdominal/induzido quimicamente , Aneurisma da Aorta Abdominal/metabolismo , Aneurisma da Aorta Abdominal/patologia , Miócitos de Músculo Liso/metabolismo , Angiotensina II/farmacologia , Modelos Animais de Doenças
5.
Clin Rehabil ; : 2692155241258740, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38863234

RESUMO

OBJECTIVE: This study aimed to assess the efficacy of radial extracorporeal shock wave therapy in treating upper limb spasticity after a stroke. DESIGN: Randomized controlled trial. SETTING: Zhujiang Hospital of Southern Medical University. SUBJECTS: This study included 95 people with stroke. INTERVENTION: The active (n = 47) and sham-placebo (n = 48) radial extracorporeal shockwave therapy groups received three treatment sessions (every third day). MAIN MEASURES: The Modified Ashworth Scale, Hmax/Mmax ratio, root mean square, co-contraction ratio, mechanical parameters of the muscle and temperature were measured at baseline and days 2, 5 and 8. RESULTS: Among the 135 potential participants screened, 100 were enrolled and allocated randomly, with 95 participants ultimately being included in the intent-to-treat analysis dataset. The active group showed significantly better improvements in upper limb spasticity and muscle function than did the sham-placebo group. Greater improvements in the Modified Ashworth Scale were observed in the active group than in the sham-placebo group (difference, -0.45; 95% CI, -0.69 to -0.22; P < 0.001). Moreover, significant differences in root mean square, co-contraction ratio and Hmax/Mmax ratio were observed between the two groups (all P < 0.001). The mechanical parameters of the biceps muscle were significantly better in the active group than in the sham-placebo group (P < 0.001). The active group had a higher temperature than the sham-placebo group, although the difference was not significant (P = 0.070). CONCLUSIONS: This study revealed that the treatment with extracorporeal shockwave therapy can relieve upper limb spasticity in people with stroke.

6.
Angew Chem Int Ed Engl ; : e202410454, 2024 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-38994649

RESUMO

Host-guest complexation offers a promising approach for mitigating surface defects in perovskite solar cells (PSCs). Crown ethers are the most widely used macrocyclic hosts for complexing perovskite surfaces, yet their supramolecular interactions and functional implications require further understanding. Here we show that the dipole moment of crown ethers serves as an indicator of supramolecular interactions with both perovskites and precursor salts. A larger dipole moment, achieved through the substitution of heteroatoms, correlates with enhanced coordination with lead cations. Perovskite films incorporating aza-crown ethers as additives exhibited improved morphology, reduced defect densities, and better energy-level alignment compared to those using native crown ethers. We report power-conversion efficiencies (PCEs) exceeding 25% for PSCs, which show enhanced long-term stability, and a record PCE of 21.5% for host-guest complexation-based perovskite solar modules with an active area of 14.0 cm2.

7.
Appl Microbiol Biotechnol ; 107(13): 4217-4232, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37209161

RESUMO

Starch and cellulose are the fundamental components of tobacco, while their excessive content will affect the quality of tobacco. Enzymatic treatment with different enzymes is a promising method to modulate the chemical composition and improve the sensory quality of tobacco leaves. In this study, enzymatic treatments, such as amylase, cellulase, and their mixed enzymes, were used to improve tobacco quality, which could alter the content of total sugar, reducing sugar, starch, and cellulose in tobacco leaves. The amylase treatment changed surface structure of tobacco leaves, increased the content of neophytadiene in tobacco by 16.48%, and improved the total smoking score of heat-not-burn (HnB) cigarette products by 5.0 points compared with the control. The Bacillus, Rubrobacter, Brevundimonas, Methylobacterium, Stenotrophomonas, Acinetobacter, Pseudosagedia-chlorotica, and Sclerophora-peronella were found to be significant biomarkers in the fermentation process by LEfSe analysis. The Basidiomycota and Agaricomycetes were significantly correlated with aroma and flavor, taste, and total score of HnB. The results showed that microbial community succession occurred due to amylase treatment, which promoted the formation of aroma compounds, and regulated the chemical composition of tobacco, and improved tobacco quality during tobacco fermentation. This study provides a method for enzymatic treatment to upgrade the quality of tobacco raw materials, thereby improving the quality of HnB cigarettes, and the potential mechanism is also revealed by chemical composition and microbial community analysis. KEY POINTS: Enzymatic treatment can change the chemical composition of tobacco leaves. The microbial community was significantly affected by enzymatic treatment. The quality of HnB cigarettes was significantly improved by amylase treatment.


Assuntos
Sistemas Eletrônicos de Liberação de Nicotina , Produtos do Tabaco , Produtos do Tabaco/análise , Fermentação , Temperatura Alta
8.
J Am Chem Soc ; 144(45): 20923-20930, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36327099

RESUMO

InP-based quantum dot (QD) light-emitting diodes (QLEDs) provide a heavy-metal-free route to size-tuned LEDs having high efficiency. The stability of QLEDs may be enhanced by replacing organic hole-injection layers (HILs) with inorganic layers. However, inorganic HILs reported to date suffer from inefficient hole injection, the result of their shallow work functions. Here, we investigate the tuning of the work function of nickel oxide (NiOx) HILs using self-assembled molecules (SAMs). Density functional theory simulations and near-edge X-ray absorption fine structure put a particular focus onto the molecular orientation of the SAMs in tuning the work function of the NiOx HIL. We find that orientation plays an even stronger role than does the underlying molecular dipole itself: SAMs having the strongest electron-withdrawing nitro group (NO2), despite having a high intrinsic dipole, show limited work function tuning, something we assign to their orientation parallel to the NiOx surface. We further find that the NO2 group─which delocalizes electrons over the molecule by resonance─induces a deep lowest unoccupied molecular orbital level that accepts electrons from QDs, producing luminescence quenching. In contrast, SAMs containing a trifluoromethyl group exhibit an angled orientation relative to the NiOx surface, better activating hole injection into the active layer without inducing luminescence quenching. We report an external quantum efficiency (EQE) of 18.8%─the highest EQE among inorganic HIL-based QLEDs (including Cd-based QDs)─in InP QLEDs employing inorganic HILs.

9.
Environ Res ; 208: 112621, 2022 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-34990612

RESUMO

Soil microbes play crucial roles in biochemical and geochemical processes in contaminated arable ecosystems. However, what factors determine the assembling process of soil bacterial community under multiple heavy metal (loid)s (HMs) stress and how communities respond to geochemical changes have rarely been understood. Therefore, a number of contaminated soils were sampled to explore the interactions among geochemical parameters, HMs and innate bacterial community. The results showed that soil biochemical activities were inhibited obviously with the increase of HMs. Significant differences were observed in bacterial composition and abundance in studied areas, with Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteria and Firmicutes governing the bacterial community structure. Redundancy analysis and variation partition analysis revealed that about 67.33% of the variation in bacterial assemblages could be explained by physiochemical parameters (21.59%), biochemical parameters (11.64%), toxic metal (loid)s (9.11%) and the interaction effect of these variables (24.99%), among which total-arsenic and moisture were the main factors. Spearman correlation analysis also demonstrated that dehydrogenase, moisture and TOC have a positive correlation with bacterial community structure with As-Cd-Pb gradient. Altogether, this study would provide a comprehensive relationship between major environmental factors and bacterial assemblages, which could offer some baseline data to investigate the mechanisms of how communities respond to physiochemical changes.


Assuntos
Metais Pesados , Poluentes do Solo , Bactérias , Ecossistema , Metais Pesados/análise , Metais Pesados/toxicidade , Solo/química , Microbiologia do Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
10.
J Am Chem Soc ; 143(29): 10970-10976, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34196528

RESUMO

Contemporary thin-film photovoltaic (PV) materials contain elements that are scarce (CIGS) or regulated (CdTe and lead-based perovskites), a fact that may limit the widespread impact of these emerging PV technologies. Tin halide perovskites utilize materials less stringently regulated than the lead (Pb) employed in mainstream perovskite solar cells; however, even today's best tin-halide perovskite thin films suffer from limited carrier diffusion length and poor film morphology. We devised a synthetic route to enable in situ reaction between metallic Sn and I2 in dimethyl sulfoxide (DMSO), a reaction that generates a highly coordinated SnI2·(DMSO)x adduct that is well-dispersed in the precursor solution. The adduct directs out-of-plane crystal orientation and achieves a more homogeneous structure in polycrystalline perovskite thin films. This approach improves the electron diffusion length of tin-halide perovskite to 290 ± 20 nm compared to 210 ± 20 nm in reference films. We fabricate tin-halide perovskite solar cells with a power conversion efficiency of 14.6% as certified in an independent lab. This represents a ∼20% increase compared to the previous best-performing certified tin-halide perovskite solar cells. The cells outperform prior earth-abundant and heavy-metal-free inorganic-active-layer-based thin-film solar cells such as those based on amorphous silicon, Cu2ZnSn(S/Se)4 , and Sb2(S/Se)3.

11.
Nat Mater ; 19(4): 412-418, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32042078

RESUMO

The composition of perovskite has been optimized combinatorially such that it often contains six components (AxByC1-x-yPbXzY3-z) in state-of-art perovskite solar cells. Questions remain regarding the precise role of each component, and the lack of a mechanistic explanation limits the practical exploration of the large and growing chemical space. Here, aided by transient photoluminescence microscopy, we find that, in perovskite single crystals, carrier diffusivity is in fact independent of composition. In polycrystalline thin films, the different compositions play a crucial role in carrier diffusion. We report that methylammonium (MA)-based films show a high carrier diffusivity of 0.047 cm2 s-1, while MA-free mixed caesium-formamidinium (CsFA) films exhibit an order of magnitude lower diffusivity. Elemental composition studies show that CsFA grains display a graded composition. This curtails electron diffusion in these films, as seen in both vertical carrier transport and surface potential studies. Incorporation of MA leads to a uniform grain core-to-edge composition, giving rise to a diffusivity of 0.034 cm2 s-1 in CsMAFA films. A model that invokes competing crystallization processes allows us to account for this finding, and suggests further strategies to achieve homogeneous crystallization for the benefit of perovskite optoelectronics.

12.
Nano Lett ; 20(5): 3694-3702, 2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32227970

RESUMO

Increasing the power conversion efficiency (PCE) of colloidal quantum dot (CQD) solar cells has relied on improving the passivation of CQD surfaces, enhancing CQD coupling and charge transport, and advancing device architecture. The presence of hydroxyl groups on the nanoparticle surface, as well as dimers-fusion between CQDs-has been found to be the major source of trap states, detrimental to optoelectronic properties and device performance. Here, we introduce a CQD reconstruction step that decreases surface hydroxyl groups and dimers simultaneously. We explored the dynamic interaction of charge carriers between band-edge states and trap states in CQDs using time-resolved spectroscopy, showing that trap to ground-state recombination occurs mainly from surface defects in coupled CQD solids passivated using simple metal halides. Using CQD reconstruction, we demonstrate a 60% reduction in trap density and a 25% improvement in charge diffusion length. These translate into a PCE of 12.5% compared to 10.9% for control CQDs.

13.
Angew Chem Int Ed Engl ; 59(33): 13977-13983, 2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32383242

RESUMO

The insertion of large organic cations in metal halide perovskites with reduced-dimensional (RD) crystal structures increases crystal formation energy and regulates the growth orientation of the inorganic domains. However, the power conversion performance is curtailed by the insulating nature of the bulky cations. Now a series of RD perovskites with 2-thiophenmethylammonium (TMA) as the intercalating cation are investigated. Compared with traditional ligands, TMA demonstrates improved electron transfer in the inorganic framework. TMA modifies the near-band-edge integrity of the RD perovskite, improving hole transport. A power conversion efficiency of 19 % is achieved, the highest to date for TMA-based RD perovskite photovoltaics; these TMA devices provide a 12 % relative increase in PCE compared to control RD perovskite devices that use PEA as the intercalating ligand, a result of the improved charge transfer from the inorganic layer to the organic ligands.

14.
J Am Chem Soc ; 141(36): 14180-14189, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31422664

RESUMO

The deployment of perovskite solar cells will rely on further progress in the operating and ambient stability of active layers and interfaces within these materials. Low-dimensional perovskites, also known as perovskite quantum wells (PQWs), utilize organic ligands to protect the perovskite lattice from degradation and offer to improve device stability; combining 2D and 3D perovskites in heterostructures has been shown to take advantage of the high efficiency of the majority 3D active layers and combine it with the improved stability of a thin 2D top layer. Prior PQWs have relied on relatively weak interwell van der Waals bonding between hydrophobic organic moieties of the ligands. Here we instead use the ligand 4-vinylbenzylammonium to form well-ordered PQWs atop a 3D perovskite layer. The ligand's vinyl group is activated using UV light which photochemically forms new covalent bonds among PQWs. UV-cross-linked 2D/3D devices show improved operational stability as well as improved long-term dark stability in air: they retain 90% of their initial efficiency after 2300 h of dark aging compared to a retention of 20% of performance in the case of 3D films. The UV-cross-linked PQWs and 2D/3D interfaces reduce device hysteresis and improve the open-circuit voltages to values up to 1.20 V, resulting in more efficient devices (PCE of up to 20.4%). This work highlights the exploitation of the chemical reactivity of PQW ligands to tailor the molecular properties of PQW interfaces for improved stability and performance in 2D/3D perovskite photovoltaics.

15.
J Am Chem Soc ; 141(20): 8296-8305, 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-31055917

RESUMO

Metal halide perovskites exhibit outstanding optoelectronic properties: superior charge carrier mobilities, low densities of deep trap states, high photoluminescence quantum yield, and wide color tunability. The introduction of dopant ions provides pathways to manipulate the electronic and chemical features of perovskites. In metal halide perovskites ABX3, where A is a monovalent cation (e.g., methylammonium (MA+), Cs+), B is the divalent metal ion(s) (e.g., Pb2+, Sn2+), and X is the halide group (e.g., Cl-, Br-, or I-), the isovalent exchange of A- and X-site ions has been widely accomplished; in contrast, strategies to exchange B-site cations are underexamined. The activation energies for vacancy-mediated diffusion of B-site cations are much higher than those for A- and X-sites, leading to slow doping processes and low doping ratios. Herein we demonstrate a new method that exchanges B-site cations in perovskites. We design a series of metal carboxylate solutions that anchor on the perovskite surface, allowing fast and efficient doping of B-sites with both homovalent and heterovalent cations (e.g., Sn2+, Zn2+, Bi3+) at room temperature. The doping process in the reduced-dimensional perovskites is complete within 1 min, whereas a similar reaction only leads to the surface attachment of dopant ions in three-dimensional structures. We offer a model based on ammonium extraction and surface ion-pair substitution.

16.
Adv Mater ; 36(13): e2303869, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37632843

RESUMO

High-performance perovskite solar cells (PSCs) typically require interfacial passivation, yet this is challenging for the buried interface, owing to the dissolution of passivation agents during the deposition of perovskites. Here, this limitation is overcome with in situ buried-interface passivation-achieved via directly adding a cyanoacrylic-acid-based molecular additive, namely BT-T, into the perovskite precursor solution. Classical and ab initio molecular dynamics simulations reveal that BT-T spontaneously may self-assemble at the buried interface during the formation of the perovskite layer on a nickel oxide hole-transporting layer. The preferential buried-interface passivation results in facilitated hole transfer and suppressed charge recombination. In addition, residual BT-T molecules in the perovskite layer enhance its stability and homogeneity. A power-conversion efficiency (PCE) of 23.48% for 1.0 cm2 inverted-structure PSCs is reported. The encapsulated PSC retains 95.4% of its initial PCE following 1960 h maximum-power-point tracking under continuous light illumination at 65 °C (i.e., ISOS-L-2I protocol). The demonstration of operating-stable PSCs under accelerated ageing conditions represents a step closer to the commercialization of this emerging technology.

17.
Science ; 385(6705): 161-167, 2024 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-38991067

RESUMO

Black-phase formamidinium lead iodide (α-FAPbI3) perovskites are the desired phase for photovoltaic applications, but water can trigger formation of photoinactive impurity phases such as δ-FAPbI3. We show that the classic solvent system for perovskite fabrication exacerbates this reproducibility challenge. The conventional coordinative solvent dimethyl sulfoxide (DMSO) promoted δ-FAPbI3 formation under high relative humidity (RH) conditions because of its hygroscopic nature. We introduced chlorine-containing organic molecules to form a capping layer that blocked moisture penetration while preserving DMSO-based complexes to regulate crystal growth. We report power conversion efficiencies of >24.5% for perovskite solar cells fabricated across an RH range of 20 to 60%, and 23.4% at 80% RH. The unencapsulated device retained 96% of its initial performance in air (with 40 to 60% RH) after 500-hour maximum power point operation.

18.
Adv Mater ; 36(21): e2313746, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38332722

RESUMO

In organic light-emitting diode (OLED), achieving high efficiency requires effective triplet exciton confinement by carrier-transporting materials, which typically have higher triplet energy (ET) than the emitter, leading to poor stability. Here, an electron-transporting material (ETM), whose ET is 0.32 eV lower than that of the emitter is reported. In devices, it surprisingly exhibits strong confinement effect and generates excellent efficiency. Additionally, the device operational lifetime is 4.9 times longer than the device with a standard ETM, 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl) phenyl (whose ET 0.36 eV is higher than the emitter). This anomalous finding is ascribed to the exceptionally long triplet state lifetime (≈0.2 s) of the ETM. It is named as long-lifetime triplet exciton reservoir effect. The systematic analysis reveals that the long triplet lifetime of ETM can compensate the requirement for high ET with the help of endothermic energy transfer. Such combination of low ET and long lifetime provides equivalent exciton confinement effect and high molecular stability simultaneously. It offers a novel molecular design paradigm for breaking the dilemma between high efficiency and prolonged operational lifetime in OLEDs.

19.
J King Saud Univ Comput Inf Sci ; 35(7): 101618, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38559705

RESUMO

Alzheimer's disease (AD) is a terrible and degenerative disease commonly occurring in the elderly. Early detection can prevent patients from further damage, which is crucial in treating AD. Over the past few decades, it has been demonstrated that neuroimaging can be a critical diagnostic tool for AD, and the feature fusion of different neuroimaging modalities can enhance diagnostic performance. Most previous studies in multimodal feature fusion have only concatenated the high-level features extracted by neural networks from various neuroimaging images simply. However, a major problem of these studies is over-looking the low-level feature interactions between modalities in the feature extraction stage, resulting in suboptimal performance in AD diagnosis. In this paper, we develop a dual-branch vision transformer with cross-attention and graph pooling, namely CsAGP, which enables multi-level feature interactions between the inputs to learn a shared feature representation. Specifically, we first construct a brand-new cross-attention fusion module (CAFM), which processes MRI and PET images by two independent branches of differing computational complexity. These features are fused merely by the cross-attention mechanism to enhance each other. After that, a concise graph pooling algorithm-based Reshape-Pooling-Reshape (RPR) framework is developed for token selection to reduce token redundancy in the proposed model. Extensive experiments on the Alzheimer's Disease Neuroimaging Initiative (ADNI) database demonstrated that the suggested method obtains 99.04%, 97.43%, 98.57%, and 98.72% accuracy for the classification of AD vs. CN, AD vs. MCI, CN vs. MCI, and AD vs. CN vs. MCI, respectively.

20.
Science ; 381(6654): 209-215, 2023 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-37440655

RESUMO

Perovskite solar cells (PSCs) consisting of interfacial two- and three-dimensional heterostructures that incorporate ammonium ligand intercalation have enabled rapid progress toward the goal of uniting performance with stability. However, as the field continues to seek ever-higher durability, additional tools that avoid progressive ligand intercalation are needed to minimize degradation at high temperatures. We used ammonium ligands that are nonreactive with the bulk of perovskites and investigated a library that varies ligand molecular structure systematically. We found that fluorinated aniliniums offer interfacial passivation and simultaneously minimize reactivity with perovskites. Using this approach, we report a certified quasi-steady-state power-conversion efficiency of 24.09% for inverted-structure PSCs. In an encapsulated device operating at 85°C and 50% relative humidity, we document a 1560-hour T85 at maximum power point under 1-sun illumination.

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