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1.
Sci Rep ; 11(1): 22160, 2021 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-34773060

RESUMO

The incidence of invasive fungal infection (IFI) in patients with acute myeloid leukemia (AML) has decreased with the introduction of antimold prophylaxis. Although acute lymphoblastic leukemia (ALL) has a lower risk of IFI than does AML, the incidences of IFI in both AML and ALL in the era of antimold prophylaxis should be re-evaluated. We analyzed adults with AML or ALL who had undergone induction, re-induction, or consolidation chemotherapy from January 2017 to December 2019 at Seoul National University Hospital. Their clinical characteristics during each chemotherapy episode were reviewed, and cases with proven or probable diagnoses were regarded as positive for IFI. Of 552 episodes (393 in AML and 159 in ALL), 40 (7.2%) were IFI events. Of the IFI episodes, 8.1% (12/148) and 5.9% (13/220) (P = 0.856) occurred in cases of ALL without antimold prophylaxis and AML with antimold prophylaxis, respectively. After adjusting for clinical factors, a lack of antimold prophylaxis (adjusted odds ratio [aOR], 3.52; 95% confidence interval [CI], 1.35-9.22; P = 0.010) and a longer duration of neutropenia (per one day, aOR, 1.02; 95% CI, 1.01-1.04; P = 0.001) were independently associated with IFI. In conclusion, the incidence of IFI in ALL without antimold prophylaxis was not lower than that in AML. A lack of antimold prophylaxis and prolonged neutropenia were independent risk factors for IFI. Clinicians should be on guard for detecting IFI in patients with ALL, especially those with risk factors.

2.
ACS Nano ; 2021 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-34797652

RESUMO

Small-molecule acceptor (SMA)-based organic solar cells (OSCs) have achieved high power conversion efficiencies (PCEs), while their long-term stabilities remain to be improved to meet the requirements for real applications. Herein, we demonstrate the use of donor-acceptor alternating copolymer-type compatibilizers (DACCs) in high-performance SMA-based OSCs, enhancing their PCE, thermal stability, and mechanical robustness simultaneously. Detailed experimental and computational studies reveal that the addition of DACCs to polymer donor (PD)-SMA blends effectively reduces PD-SMA interfacial tensions and stabilizes the interfaces, preventing the coalescence of the phase-separated domains. As a result, desired morphologies with exceptional thermal stability and mechanical robustness are obtained for the PD-SMA blends. The addition of 20 wt % DACCs affords OSCs with a PCE of 17.1% and a cohesive fracture energy (Gc) of 0.89 J m-2, higher than those (PCE = 13.6% and Gc = 0.35 J m-2) for the control OSCs without DACCs. Moreover, at an elevated temperature of 120 °C, the OSCs with 20 wt % DACC exhibit excellent morphological stability, retaining over 95% of the initial PCE after 300 h. In contrast, the control OSCs without the DACC rapidly degraded to below 60% of the initial PCE after 144 h.

3.
Adv Mater ; : e2107361, 2021 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-34820914

RESUMO

High efficiency and mechanical robustness are both crucial for the practical applications of all-polymer solar cells (all-PSCs) in stretchable and wearable electronics. In this regard, we report a series of new polymer acceptors (PA s) by incorporating a flexible conjugation-break spacer (FCBS) to achieve highly efficient and mechanically robust all-PSCs. Incorporation of FCBS affords the effective modulation of the crystallinity and pre-aggregation of the PA s, and achieves the optimal blend morphology with polymer donor (PD ), increasing both the photovoltaic and mechanical properties of all-PSCs. In particular, the all-PSC based on PYTS-0.3 as a PA incorporated with 30% FCBS and a PD (PBDB-T) demonstrates a high power conversion efficiency (PCE) of 14.68% and excellent mechanical stretchability with a crack onset strain (COS) of 21.64% and toughness of 3.86 MJ m-3 , which is significantly superior to those of devices with the PA without the FCBS (PYTS-0.0, PCE = 13.01% and toughness = 2.70 MJ m-3 ). To date, this COS is the highest value reported for PSCs with PCEs of over 8% without any insulating additives. These results reveal that the introduction of FCBS into the conjugated backbone is a highly feasible strategy to simultaneously improve the PCE and stretchability of PSCs. This article is protected by copyright. All rights reserved.

4.
JACS Au ; 1(5): 612-622, 2021 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-34467323

RESUMO

The development of small-molecule acceptors (SMAs) has significantly enhanced the power conversion efficiency (PCE) of polymer solar cells (PSCs); however, the inferior mechanical properties of SMA-based PSCs often limit their long-term stability and application in wearable power generators. Herein, we demonstrate a simple and effective strategy for enhancing the mechanical robustness and PCE of PSCs by incorporating a high-molecular-weight (MW) polymer acceptor (P A, P(NDI2OD-T2)). The addition of 10-20 wt % P A leads to a more than 4-fold increase in the mechanical ductility of the SMA-based PSCs in terms of the crack onset strain (COS). At the same time, the incorporation of P A into the active layer improves the charge transport and recombination properties, increasing the PCE of the PSC from 14.6 to 15.4%. The added P As act as tie molecules, providing mechanical and electrical bridges between adjacent domains of SMAs. Thus, for the first time, we produce highly efficient and mechanically robust PSCs with a 15% PCE and 10% COS at the same time, thereby demonstrating their great potential as stretchable or wearable power generators. To understand the origin of the dual enhancements realized by P A, we investigate the influence of the P A content on electrical, structural, and morphological properties of the PSCs.

5.
J Fungi (Basel) ; 7(8)2021 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-34436136

RESUMO

We investigated mortality and predictors of mortality due to intensive care unit-associated candidemia (ICUAC) versus non-ICUAC by Candida species. This study included all candidemia cases in 11 hospitals from 2017 to 2018 in South Korea. The all-cause mortality rates in all 370 patients with ICUAC were approximately twofold higher than those in all 437 patients with non-ICUAC at 7 days (2.3-fold, 31.1%/13.3%), 30 days (1.9-fold, 49.5%/25.4%), and 90 days (1.9-fold, 57.8%/30.9%). Significant species-specific associations with 7- and 30-day ICUAC-associated mortality were not observed. Multivariate analysis revealed that ICU admission was an independent predictor of Candida glabrata (OR, 2.07-2.48) and Candida parapsilosis-associated mortality (OR, 6.06-11.54). Fluconazole resistance was a predictor of C. glabrata-associated mortality (OR, 2.80-5.14). Lack (less than 3 days) of antifungal therapy was the strongest predictor of 7-day mortality due to ICUAC caused by Candida albicans (OR, 18.33), Candida tropicalis (OR, 10.52), and C. glabrata (OR, 21.30) compared with 30- and 90-day mortality (OR, 2.72-6.90). C. glabrata ICUAC had a stronger association with lack of antifungal therapy (55.2%) than ICUAC caused by other species (30.6-36.7%, all p < 0.05). Most predictors of mortality associated with ICUAC were distinct from those associated with non-ICUAC and were mediated by Candida species.

6.
Sci Adv ; 7(27)2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34193431

RESUMO

Electronic skins (e-skins)-electronic sensors mechanically compliant to human skin-have long been developed as an ideal electronic platform for noninvasive human health monitoring. For reliable physical health monitoring, the interface between the e-skin and human skin must be conformal and intact consistently. However, conventional e-skins cannot perfectly permeate sweat in normal day-to-day activities, resulting in degradation of the intimate interface over time and impeding stable physical sensing. Here, we present a sweat pore-inspired perforated e-skin that can effectively suppress sweat accumulation and allow inorganic sensors to obtain physical health information without malfunctioning. The auxetic dumbbell through-hole patterns in perforated e-skins lead to synergistic effects on physical properties including mechanical reliability, conformability, areal mass density, and adhesion to the skin. The perforated e-skin allows one to laminate onto the skin with consistent homeostasis, enabling multiple inorganic sensors on the skin to reliably monitor the wearer's health over a period of weeks.

7.
ACS Appl Mater Interfaces ; 13(30): 35595-35605, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34286951

RESUMO

For enhancing the performance and long-term stability of perovskite solar cell (PSC) devices, interfacial engineering between the perovskite and hole-transporting material (HTM) is important. We developed a fluorinated conjugated polymer PFPT3 and used it as an interfacial layer between the perovskite and HTM layers in normal-type PSCs. Interaction of perovskite and PFPT3 via Pb-F bonding effectively induces an interfacial dipole moment, which resulted in energy-level bending; this was favorable for charge transfer and hole extraction at the interface. The PSC device achieved an increased efficiency of 22.00% with an open-circuit voltage of 1.13 V, short-circuit current density of 24.34 mA/cm2, and fill factor of 0.80 from a reverse scan and showed an averaged power conversion efficiency of 21.59%, which was averaged from forward and reverse scans. Furthermore, the device with PFPT3 showed much improved stability under an 85% RH condition because hydrophobic PFPT3 reduced water permeation into the perovskite layer, and more importantly, the enhanced contact adhesion at the PFPT3-mediated perovskite/HTM interface suppressed surface delamination and retarded water intrusion. The fluorinated conjugated polymeric interfacial material is effective for improving not only the efficiency but also the stability of the PSC devices.

8.
ACS Appl Mater Interfaces ; 13(30): 36253-36261, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34310107

RESUMO

The arrangement of mesogenic units determines mechanical response of the liquid crystal polymer network (LCN) film to heat. Here, we show an interesting approach to programming three-dimensional patterns of the LCN films with periodic topological defects generated by applying an electric field. The mechanical properties of three representative patterned LCN films were investigated in terms of the arrangement of mesogenic units through tensile testing. Remarkably, it was determined that LCN films showed enhanced toughness and ductility as defects increased in a given area, which is related to the elastic modulus mismatch that mitigates crack propagation. Our platform can also be used to modulate the frictional force of the patterned LCN films by varying the temperature, which can provide insight into the multiplex mechanical properties of LCN films.

9.
Ann Lab Med ; 41(6): 588-592, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34108286

RESUMO

The rapid antigen test (RAT) for coronavirus disease (COVID-19) represents a potent diagnostic method in situations of limited molecular testing resources. However, considerable performance variance has been reported with the RAT. We evaluated the clinical performance of Standard Q COVID-19 RAT (SQ-RAT; SD Biosensor, Suwon, Korea), the first RAT approved by the Korean Ministry of Food and Drug Safety. In total, 680 nasopharyngeal swabs previously tested using real-time reverse-transcription PCR (rRT-PCR) were retested using SQ-RAT. The clinical sensitivity of SQ-RAT relative to that of rRT-PCR was 28.7% for all specimens and was 81.4% for specimens with RNA-dependent RNA polymerase gene (RdRp) threshold cycle (Ct) values ≤23.37, which is the limit of detection of SQ-RAT. The specificity was 100%. The clinical sensitivity of SQ-RAT for COVID-19 diagnosis was assessed based on the Ct distribution at diagnosis of 33,294 COVID-19 cases in Korea extracted from the laboratory surveillance system of Korean Society for Laboratory Medicine. The clinical sensitivity of SQ-RAT for COVID-19 diagnosis in the Korean population was 41.8%. Considering the molecular testing capacity in Korea, use of the RAT for COVID-19 diagnosis appears to be limited.


Assuntos
COVID-19/diagnóstico , RNA Polimerase Dependente de RNA/genética , SARS-CoV-2/genética , COVID-19/virologia , Teste para COVID-19/métodos , Humanos , Nasofaringe/virologia , RNA Viral/análise , RNA Viral/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , República da Coreia , SARS-CoV-2/isolamento & purificação
10.
Proteomics ; 21(11-12): e2000278, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33945677

RESUMO

In managing patients with coronavirus disease 2019 (COVID-19), early identification of those at high risk and real-time monitoring of disease progression to severe COVID-19 is a major challenge. We aimed to identify potential early prognostic protein markers and to expand understanding of proteome dynamics during clinical progression of the disease. We performed in-depth proteome profiling on 137 sera, longitudinally collected from 25 patients with COVID-19 (non-severe patients, n = 13; patients who progressed to severe COVID-19, n = 12). We identified 11 potential biomarkers, including the novel markers IGLV3-19 and BNC2, as early potential prognostic indicators of severe COVID-19. These potential biomarkers are mainly involved in biological processes associated with humoral immune response, interferon signalling, acute phase response, lipid metabolism, and platelet degranulation. We further revealed that the longitudinal changes of 40 proteins persistently increased or decreased as the disease progressed to severe COVID-19. These 40 potential biomarkers could effectively reflect the clinical progression of the disease. Our findings provide some new insights into host response to SARS-CoV-2 infection, which are valuable for understanding of COVID-19 disease progression. This study also identified potential biomarkers that could be further validated, which may support better predicting and monitoring progression to severe COVID-19.


Assuntos
COVID-19 , Interações Hospedeiro-Patógeno/genética , Proteoma , Transcriptoma/genética , Idoso , Biomarcadores/sangue , COVID-19/diagnóstico , COVID-19/genética , COVID-19/metabolismo , Progressão da Doença , Feminino , Perfilação da Expressão Gênica , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Prognóstico , Proteoma/análise , Proteoma/genética , Proteoma/metabolismo , Proteômica
11.
Nat Biomed Eng ; 5(7): 772-782, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33941897

RESUMO

Continuous detection of raised intraocular pressure (IOP) could benefit the monitoring of patients with glaucoma. Current contact lenses with embedded sensors for measuring IOP are rigid, bulky, partially block vision or are insufficiently sensitive. Here, we report the design and testing in volunteers of a soft and transparent contact lens for the quantitative monitoring of IOP in real time using a smartphone. The contact lens incorporates a strain sensor, a wireless antenna, capacitors, resistors, stretchable metal interconnects and an integrated circuit for wireless communication. In rabbits, the lens provided measurements that match those of a commercial tonometer. In ten human participants, the lens proved to be safe, and reliably provided accurate quantitative measurements of IOP without inducing inflammation.


Assuntos
Pressão Intraocular/fisiologia , Monitorização Fisiológica/métodos , Adulto , Animais , Bovinos , Telefone Celular , Lentes de Contato , Feminino , Humanos , Monitorização Fisiológica/instrumentação , Impressão Tridimensional , Coelhos , Tecnologia sem Fio
12.
Nat Commun ; 12(1): 2864, 2021 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-34001906

RESUMO

Stretchable organic light-emitting diodes are ubiquitous in the rapidly developing wearable display technology. However, low efficiency and poor mechanical stability inhibit their commercial applications owing to the restrictions generated by strain. Here, we demonstrate the exceptional performance of a transparent (molybdenum-trioxide/gold/molybdenum-trioxide) electrode for buckled, twistable, and geometrically stretchable organic light-emitting diodes under 2-dimensional random area strain with invariant color coordinates. The devices are fabricated on a thin optical-adhesive/elastomer with a small mechanical bending strain and water-proofed by optical-adhesive encapsulation in a sandwiched structure. The heat dissipation mechanism of the thin optical-adhesive substrate, thin elastomer-based devices or silicon dioxide nanoparticles reduces triplet-triplet annihilation, providing consistent performance at high exciton density, compared with thick elastomer and a glass substrate. The performance is enhanced by the nanoparticles in the optical-adhesive for light out-coupling and improved heat dissipation. A high current efficiency of ~82.4 cd/A and an external quantum efficiency of ~22.3% are achieved with minimum efficiency roll-off.

13.
J Korean Med Sci ; 36(14): e101, 2021 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-33847084

RESUMO

We evaluated the Standard Q COVID-19 Ag test for the diagnosis of coronavirus disease 2019 (COVID-19) compared to the reverse transcription-polymerase chain reaction (RT-PCR) test. We applied both tests to patients who were about to be hospitalized, had visited an emergency room, or had been admitted due to COVID-19 confirmed by RT-PCR. Two nasopharyngeal swabs were obtained; one was tested by RT-PCR and the other by the Standard Q COVID-19 Ag test. A total of 118 pairs of tests from 98 patients were performed between January 5 and 11, 2021. The overall sensitivity and specificity for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for the Standard Q COVID-19 Ag test compared to RT-PCR were 17.5% (95% confidence interval [CI], 8.8-32.0%) and 100% (95% CI, 95.3-100.0%). Analysis of the results using RT-PCR cycle thresholds of ≤ 30 or ≤ 25 increased the sensitivity to 26.9% (95% CI, 13.7-46.1%), and 41.1% (95% CI, 21.6-64.0%), respectively.


Assuntos
Antígenos Virais/imunologia , Teste para COVID-19 , COVID-19/diagnóstico , COVID-19/imunologia , Serviço Hospitalar de Emergência , Reações Falso-Positivas , Humanos , Nasofaringe/virologia , Valor Preditivo dos Testes , Probabilidade , Padrões de Referência , Reprodutibilidade dos Testes , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sensibilidade e Especificidade
14.
ACS Appl Mater Interfaces ; 13(18): 21299-21309, 2021 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-33909397

RESUMO

Two-dimensional transition-metal dichalcogenides (TMDs) are of particular interest as a new active material for future triboelectric nanogenerators (TENGs) owing to their excellent electrical properties, optical transparency, flexibility, ultrathin thickness, and biocompatibility. Here, we propose a new approach to engineer the surface of TMDs via conjugation with thiolated ligands having different alkane chain lengths and to develop TMD-based TENG devices that exhibit enhanced output performance for the first time. The triboelectric charging behaviors of ligand-conjugated TMDs are successfully investigated, and the electrical output performance of TMD TENGs based on TMD-to-polymer device geometries with a vertical contact-separation mode is dramatically improved, exhibiting an output voltage of 12.2 V and a power density of 138 mW/m2. Furthermore, the ligand-conjugated TMD TENG device exhibits a highly stable operation under repeated contact and separation over 10 000 cycles, as well as high chemical stability, as a result of novel defect engineering via thiolated ligand conjugation. Detailed investigation reveals that the improved performance of the ligand-conjugated TMD TENG device originates from the synergistic effect of defect engineering and the p-type doping effect of TMDs, correlated with the increased electric potential difference between triboelectric layers. These findings provide a new potential of TMDs as a promising building block for the next-generation energy harvesting system.

15.
Ann Lab Med ; 41(5): 463-468, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-33824234

RESUMO

Background: Seven genotypic subtypes of Mycobacterium kansasii were recently demonstrated to represent distinct species based on phylogenomic analysis. Mycobacterium kansasii sensu stricto (formerly known as subtype 1) is most frequently associated with human diseases; only a few studies have compared the diverse clinical characteristics of M. kansasii subtypes, including their drug susceptibilities. We determined the actual incidence of infections caused by each subtype of M. kansasii and identified their clinical characteristics. Methods: We subtyped isolates identified as M. kansasii over the last 10 years at a tertiary care hospital. Percent identity score of stored sequencing data was calculated using curated reference sequences of all M. kansasii subtypes. Clinical characteristics were compared between those classified as subtype 1 and other subtypes. Student's t-test, Wilcoxon rank-sum test, and Fisher's exact test were used for comparisons. Results: Overall, 21.7% of the isolates were identified as species distinct from M. kansasii. The proportion of patients with subtype 1 M. kansasii infection who received treatment was significantly higher than that of patients with other subtype infections (55.3% vs. 7.7%, P=0.003). Only patients with subtype 1 infection received surgical treatment. Non-subtype 1 M. kansasii isolates showed a higher frequency of resistance to ciprofloxacin and trimethoprim/sulfamethoxazole. Conclusions: Non-subtype 1 M. kansasii isolates should be separately identified in routine clinical laboratory tests for appropriate treatment selection.


Assuntos
Infecções por Mycobacterium não Tuberculosas , Mycobacterium kansasii , Ciprofloxacina/farmacologia , Ciprofloxacina/uso terapêutico , Humanos , Infecções por Mycobacterium não Tuberculosas/diagnóstico , Infecções por Mycobacterium não Tuberculosas/epidemiologia , Mycobacterium kansasii/genética , Filogenia
16.
Biomed Res Int ; 2021: 6667623, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33763483

RESUMO

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is widely used in clinical microbiology laboratories because it is cost-effective, reliable, and fast. This study is aimed at comparing the identification performance of the recently developed Autof ms1000 (Autobio, China) with that of the Bruker Biotyper (Bruker Daltonics, Germany). From January to June 2020, 205 preserved strains and 302 clinical isolates were used for comparison. Bacteria were tested with duplicates of the direct transfer method, and formic acid extraction was performed if the results were not at the species level. Fungi were tested with formic acid extraction followed by ethanol extraction methods. 16S rRNA or ITS region sequence analysis was performed on isolates that could not be identified by any of the instruments and on isolates that showed inconsistent results. The time to result of each instrument was also compared. Among preserved strains, species-level identification results were obtained in 202 (98.5%) strains by the Autof ms1000 and 200 (97.6%) strains by the Bruker Biotyper. Correct identification at the species/complex level was obtained for 200 (97.6%) strains by the Autof ms1000 and for 199 (97.1%) strains by the Bruker Biotyper. Among clinical isolates, species-level identification results were obtained in 301 (99.7%) strains and 300 (99.3%) strains by the Autof ms1000 and Bruker Biotyper, respectively. Correct identification at the species/complex level was achieved for 299 (99.0%) strains by the Autof ms1000 and for 300 (99.3%) strains by the Bruker Biotyper. The time to analyze 96 spots was approximately 14 min for the Autof ms1000 and approximately 27 min for the Bruker Biotyper. The two instruments showed comparable performance for the routine identification of clinical microorganisms. In addition, the Autof ms1000 has a short test time, making it convenient for use in clinical microbiology laboratories.


Assuntos
Bactérias , Técnicas de Tipagem Bacteriana , RNA Bacteriano , RNA Ribossômico 16S , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Bactérias/classificação , Bactérias/genética , Técnicas de Tipagem Bacteriana/instrumentação , Técnicas de Tipagem Bacteriana/métodos , Humanos , RNA Bacteriano/análise , RNA Bacteriano/genética , RNA Ribossômico 16S/análise , RNA Ribossômico 16S/genética
17.
Ann Clin Lab Sci ; 51(1): 140-144, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33653794

RESUMO

We compared SARS-CoV-2 detection rate of different respiratory specimens (nasopharyngeal swab [NPS], n=92; oropharyngeal swab [OPS], n=18; sputum, n=11). We also compared cycle threshold (Ct) values of paired specimen types obtained from the same patient on the same day. Then we characterized viral load kinetics of NPS (n=142), OPS (n=126), and sputum (n=75), during disease course. Sputum samples showed higher detection rate than NPS, and OPS exhibited the lowest detection rate. The median Ct values in NPS were significantly lower than in paired OPS, and higher than in paired sputum, respectively (P<0.05). During the disease course, viral load was the lowest in OPS and the highest in sputum samples.


Assuntos
SARS-CoV-2/isolamento & purificação , Manejo de Espécimes , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , COVID-19/diagnóstico , COVID-19/virologia , Criança , Feminino , Humanos , Cinética , Masculino , Pessoa de Meia-Idade , Nasofaringe/virologia , Reação em Cadeia da Polimerase em Tempo Real , Escarro/virologia , Carga Viral , Adulto Jovem
18.
ACS Appl Mater Interfaces ; 13(14): 16650-16659, 2021 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-33788536

RESUMO

A fundamental understanding of the mechanical behavior of the indium tin oxide (ITO) layer is very important because cracking and delamination of the ITO layers have been a critical obstacle for mechanically robust flexible electronics. In this study, the intrinsic mechanical properties of ITO thin films without a substrate were measured by utilizing a freestanding tensile testing method. Young's modulus (89 ± 1 GPa), elongation (0.34 ± 0.02%), and tensile strength (293 ± 13 MPa) of amorphous as-deposited ITO thin films were successfully measured. The sheet resistance, transparency, and thickness of the as-deposited films were 32.9 ± 0.5 Ω/sq, 92.7% (400-700 nm), and 152 ± 6 nm, respectively. First, we investigated the effects of annealing temperature on the mechanical properties of ITO thin films. For 100- and 150 °C-annealed ITO thin films, which were amorphous, Young's modulus, elongation, and tensile strength were enhanced by increasing the packing density and reducing the structural defects. For 200 °C-annealed ITO thin films, which were polycrystalline, Young's modulus was further increased because of their highly packed crystalline nature. However, there was a significant decrease in elongation and tensile strength because grain boundaries act as critical defects. Next, the annealing time was varied from 0.5 to 6 h for a better understanding of the effects of the annealing time. As a result, the maximum elongation (0.54 ± 0.03%) and tensile strength (589 ± 11 MPa) were obtained at 150 °C for 1 h. Annealing for 1 h was appropriate for sufficient defect reduction; however, excessive annealing for more than 1 h increased the degree of partial crystallization of the ITO thin films. The proposed annealing conditions and the corresponding mechanical properties provide guidelines for the optimum annealing process of ITO thin films and quantitative data for mechanical analysis to design mechanically robust flexible electronics.

20.
Adv Mater ; 33(13): e2007186, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33634556

RESUMO

A robust Cu conductor on a glass substrate for thin-film µLEDs using the flash-induced chemical/physical interlocking between Cu and glass is reported. During millisecond light irradiation, CuO nanoparticles (NPs) on the display substrate are transformed into a conductive Cu film by reduction and sintering. At the same time, intensive heating at the boundary of CuO NPs and glass chemically induces the formation of an ultrathin Cu2 O interlayer within the Cu/glass interface for strong adhesion. Cu nanointerlocking occurs by transient glass softening and interface fluctuation to increase the contact area. Owing to these flash-induced interfacial interactions, the flash-activated Cu electrode exhibits an adhesion energy of 10 J m-2 , which is five times higher than that of vacuum-deposited Cu. An AlGaInP thin-film vertical µLED (VLED) forms an electrical interconnection with the flash-induced Cu electrode via an ACF bonding process, resulting in a high optical power density of 41 mW mm-2 . The Cu conductor enables reliable VLED operation regardless of harsh thermal stress and moisture infiltration under a high-temperature storage test, temperature humidity test, and thermal shock test. 50 × 50 VLED arrays transferred onto the flash-induced robust Cu electrode show high illumination yield and uniform distribution of forward voltage, peak wavelength, and device temperature.

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