Overcoming the Interfacial Photocatalytic Degradation of Nonfullerene Acceptor-Based Organic Photovoltaics by Introducing a UV-A-Insensitive Titanium Suboxide Layer.

Although recent dramatic advances in power conversion efficiencies (PCEs) have resulted in values over 19%, the poor photostability of organic photovoltaics (OPVs) has been a serious bottleneck to their commercialization. The photocatalytic effect, which is caused by incident ultraviolet-A (UV-A, 320-400 nm) light in the most commonly used zinc oxide (ZnOX) electron transport layer (ETL), significantly deteriorates the photostability of OPVs. In this work, we develop a new and facile method to enhance the photostability of nonfullerene acceptor-based OPVs by introducing UV-A-insensitive titanium suboxide (TiOX) ETL. Through an in-depth analysis of mass information at the interface between the ETL and photoactive layer, we confirm that the UV-A-insensitive TiOX suppresses the photocatalytic effect. The resulting device employing the TiOX ETL shows excellent photostability, obtaining 80% of the initial PCE for up to 200 h under 1 sun illumination, which is 10 times longer than that of the conventional ZnOX system (19 h).

In Situ Doping of the PEDOT Top Electrode for All-Solution-Processed Semitransparent Organic Solar Cells.

The development of an ideal solution-processable transparent electrode has been a challenge in the field of all-solution-processed semitransparent organic solar cells (ST-OSCs). We present a novel poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) top electrode for all-solution-processed ST-OSCs through in situ doping of PEDOT:PSS. A strongly polarized long perfluoroalkyl (n = 8) chain-anchored sulfonic acid effectively eliminates insulating PSS and spontaneously crystallizes PEDOT at room temperature, leading to outstanding electrical properties and transparency of PEDOT top electrodes. Doped PEDOT-based ST-OSCs yield a high power conversion efficiency of 10.9% while providing an average visible transmittance of 26.0% in the visible range. Moreover, the strong infrared reflectivity of PEDOT enables ST-OSCs to reject 62.6% of the heat emitted by sunlight (76.7% from infrared radiation), outperforming the thermal insulation capability of commercial tint films. This light management approach using PEDOT enables ST-OSCs to simultaneously provide energy generation and energy savings, making it the first discovery toward sustainable energy in buildings.

New Non-Fullerene Acceptor with Extended Conjugation of Cyclopenta [2,1-b:3,4-b'] Dithiophene for Organic Solar Cells.

Herein, we design and characterize 9-heterocyclic ring non-fullerene acceptors (NFAs) with the extended backbone of indacenodithiophene by cyclopenta [2,1-b:3,4-b'] dithiophene (CPDT). The planar conjugated CPDT donor enhances absorption by reducing vibronic transition and charge transport. Developed NFAs with different end groups shows maximum absorption at approximately 790-850 nm in film. Because of the electronegative nature of the end-group, the corresponding acceptors showed deeper LUMO energy levels and red-shifted ultraviolet absorption. We investigate the crystallinity, film morphology, surface energy, and electronic as well as photovoltaic performance. The organic photovoltaic cells using novel NFAs with the halogen end groups fluorine or chlorine demonstrate better charge collection and faster exciton dissociation than photovoltaic cells using NFAs with methyl or lacking a substituent. Photovoltaic devices constructed from m-Me-ITIC with various end groups deliver power conversion efficiencies of 3.6-11.8%.

Facile Direct C-H Arylation Polymerization of Conjugated Polymer, PDCBT, for Organic Solar Cells.

Direct arylation polymerization (DArP) is a synthetic method for conjugated polymers; in DArP, organometallic functionalization steps are omitted and there are no toxic byproducts. As a result, it is considered a more sustainable alternative compared to conventional methods such as Stille polymerization. To explore the possibility of DArP-based polymers as donor materials in organic solar cells (OSCs), a series of conjugated polymers based on the structure of PDCBT (poly[2,2''''-bis[[(2-butyloctyl)oxy]carbonyl][2,2':5',2'':5'',2'''-quaterthiophene]-5,5'''-diyl]) are synthesized using DArP and Stille polymerization. By controlling the monomer concentration and reaction time in DArP, DArP-5 with the highest Mn (21.9 kDa) can be obtained and its optoelectronic properties, electrochemical properties, and microscopic molecular ordering are comparable to those of Stille-based PDCBT (Stille-P). Analysis of the polymer structure indicates no structural defects such as crosslinking from undesired ß-coupling reactions in DArP-5. Upon blending with the PC71 BM acceptor molecule, an increase in the crystallite size of DArP-5 is also observed. In OSC devices with a polymer:PC71 BM bulk-heterojunction photoactive layer, DArP-5 demonstrates a comparable power conversion efficiency of 5.8% with that of Stille-P (5.5%). These results prove that DArP is suitable for synthesizing PDCBT, and DArP-based PDCBT can be used in OSCs as an alternative of Stille-based one.

Direct Observation of Confinement Effects of Semiconducting Polymers in Polymer Blend Electronic Systems.

The advent of special types of polymeric semiconductors, known as "polymer blends," presents new opportunities for the development of next-generation electronics based on these semiconductors' versatile functionalities in device applications. Although these polymer blends contain semiconducting polymers (SPs) mixed with a considerably high content of insulating polymers, few of these blends unexpectedly yield much higher charge carrier mobilities than those of pure SPs. However, the origin of such an enhancement has remained unclear owing to a lack of cases exhibiting definite improvements in charge carrier mobility, and the limited knowledge concerning the underlying mechanism thereof. In this study, the morphological changes and internal nanostructures of polymer blends based on various SP types with different intermolecular interactions in an insulating polystyrene matrix are investigated. Through this investigation, the physical confinement of donor-acceptor type SP chains in a continuous nanoscale network structure surrounded by polystyrenes is shown to induce structural ordering with more straight edge-on stacked SP chains. Hereby, high-performance and transparent organic field-effect transistors with a hole mobility of ≈5.4 cm2 V-1 s-1 and an average transmittance exceeding 72% in the visible range are achieved.

Proposed nomogram predicting neoplastic ampullary obstruction in patients with a suspected ampulla of Vater lesion on CT.

PURPOSE: To stratify and weigh the computed tomography (CT) imaging and clinical features differentiating a neoplastic ampullary obstruction from a non-neoplastic ampullary obstruction and to develop a nomogram for estimating individualized risk of neoplastic potential in patients with a suspected ampulla of Vater (AOV) lesion on CT. METHODS: 135 patients (92 non-neoplastic and 43 neoplastic) with a suspected ampullary obstruction on a CT scan between February 2015 and May 2019 were included after the exclusion criteria were applied. Significant imaging and clinical findings of the neoplastic lesions were assessed using univariate and multivariate logistic regression analyses. Based on the significant variables in the multivariate analysis, a nomogram was developed to predict neoplastic potential in patients suspected of ampullary obstruction. The area under the receiver operating characteristic curve (AUC) was used to assess the diagnostic value in the external validation cohort (36 non-neoplastic and 13 neoplastic). RESULTS: The multivariate analysis revealed that the presence of an AOV mass (odds ratio (OR), 77.21; 95% confidence intervals (CI) 1.51-3950.38), AOV size > 12 mm (OR, 23.93; 95% CI 2.96-193.60), total bilirubin > 1.2 mg/dl (OR, 9.99; 95% CI 1.37-73.06) and age ≤ 63 years (OR, 7.52; 95% CI 1.33-42.48) were independent significant parameters that predicted a neoplastic lesion in the AOV. The AUC for the nomogram was 0.93 on the internal validation and 0.91 (95% CI 0.79-0.97) on the external validation. CONCLUSIONS: A nomogram using imaging and clinical findings was useful to estimate a neoplastic ampullary obstruction in patients with a suspected AOV lesion on CT and suggests a further evaluation.

Interface Engineering for Fabricating Semitransparent and Flexible Window-Film-Type Organic Solar Cells.

We fabricated window-film-type organic photovoltaics with flexible transparent electrodes (FTEs). By overcoming the poor adhesion between layers, we created ultrathin metal electrodes (bottom FTE) on flexible substrates and transferred conducting polymers onto the photoactive layer (top FTE), providing power conversion efficiencies of 4.9% (7.4%) with average visible transmittances of 38% (18%).

Unsymmetrical Small Molecules for Broad-Band Photoresponse and Efficient Charge Transport in Organic Phototransistors.

Organic photosensitizers have been investigated as effective light-sensing elements that can promote strong absorption with high field-effect mobility in organic phototransistors (OPTs). In this study, a novel organic photosensitizer is synthesized to demonstrate broad-band photoresponse with enhanced electrical performance. An unsymmetrical small molecule of a solubilizing donor (Dsol)-acceptor (A)-dye donor (Ddye) type connected with a twisted conjugation system is designed for broad-band detection (ranging from 250 to 700 nm). This molecule has high solubility, thereby facilitating the formation of uniformly dispersed nanoparticles in an insulating polymer matrix, which is deposited on top of OPT semiconductors by a simple solution process. The broad-band photodetection shown by the organic photosensitizer is realized with improved mobility close to an order of magnitude and high on/off current ratio (∼105) of the organic semiconductor. Furthermore, p-type charge transport behavior in the channel of the OPT is enhanced through the intrinsic electron-accepting ability of the organic photosensitizer caused by the unique molecular configuration. These structural properties of organic photosensitizers contribute to an improvement in broad-band photosensing systems with new optoelectronic properties and functionalities.

Tail state limited photocurrent collection of thick photoactive layers in organic solar cells.

We analyse organic solar cells with four different photoactive blends exhibiting differing dependencies of short-circuit current upon photoactive layer thickness. These blends and devices are analysed by transient optoelectronic techniques of carrier kinetics and densities, air photoemission spectroscopy of material energetics, Kelvin probe measurements of work function, Mott-Schottky analyses of apparent doping density and by device modelling. We conclude that, for the device series studied, the photocurrent loss with thick active layers is primarily associated with the accumulation of photo-generated charge carriers in intra-bandgap tail states. This charge accumulation screens the device internal electrical field, preventing efficient charge collection. Purification of one studied donor polymer is observed to reduce tail state distribution and density and increase the maximal photoactive thickness for efficient operation. Our work suggests that selecting organic photoactive layers with a narrow distribution of tail states is a key requirement for the fabrication of efficient, high photocurrent, thick organic solar cells.

Erratum: Diseleno[3,2-b:2',3'-d]selenophene-Containing High-Mobility Conjugated Polymer for Organic Field-Effect Transistors.

[This corrects the article DOI: 10.1002/advs.201900245.].

Diseleno[3,2-b:2',3'-d]selenophene-Containing High-Mobility Conjugated Polymer for Organic Field-Effect Transistors.

The synthesis of a diseleno[3,2-b:2',3'-d]selenophene (DSS) composed of three fused selenophenes is reported and it is used as a building block for the preparation of a high hole mobility conjugated polymer (PDSSTV). The polymer demonstrates strong intermolecular interactions even in solution, despite steric repulsion between the large Se atom in DSS and adjacent (Cß)-H atoms which leads to a partially twisted confirmation PDSSTV. Nevertheless, 2D grazing incidence X-ray diffraction (2D-GIXD) analysis reveals that the polymer tends to align in a highly ordered edge-on orientation after thermal annealing. The polymer demonstrates promising performance in a field-effect transistor device with saturated hole mobility up to 2 cm2 V-1 s-1 obtained under relatively low gate voltages of -30 V. The ultilization of a Se-containing fused aromatic system, therefore, appears to be a promising avenue for the development of high-performance conjugated polymers.

Highly Deformable and See-Through Polymer Light-Emitting Diodes with All-Conducting-Polymer Electrodes.

Despite the high expectation of deformable and see-through displays for future ubiquitous society, current light-emitting diodes (LEDs) fail to meet the desired mechanical and optical properties, mainly because of the fragile transparent conducting oxides and opaque metal electrodes. Here, by introducing a highly conductive nanofibrillated conducting polymer (CP) as both deformable transparent anode and cathode, ultraflexible and see-through polymer LEDs (PLEDs) are demonstrated. The CP-based PLEDs exhibit outstanding dual-side light-outcoupling performance with a high optical transmittance of 75% at a wavelength of 550 nm and with an excellent mechanical durability of 9% bending strain. Moreover, the CP-based PLEDs fabricated on 4 µm thick plastic foils with all-solution processing have extremely deformable and foldable light-emitting functionality. This approach is expected to open a new avenue for developing wearable and attachable transparent displays.

The Effect of Fluorine Substitution on the Molecular Interactions and Performance in Polymer Solar Cells.

Fluorine (F) substitution on conjugated polymers in polymer solar cells (PSCs) has a diverse effect on molecular properties and device performance. We present a series of three D-A type conjugated polymers (PBT, PFBT, and PDFBT) based on dithienothiophene and benzothiadiazole units with different numbers of F atoms to explain the influence of F substitution by comparing the molecular interactions of the polymers and the recombination kinetics in PSCs. The preaggregation behavior of PFBT and PDFBT in o-DCB at the UV-vis absorption spectra proves that both polymers have strong intermolecular interactions. Besides, more closely packed structures and change into face-on orientation of fluorinated polymers are observed in polymer:PC71BM blends by GIXD which is beneficial for charge transport and, ultimately, for current density in PSCs (4.3, 13.0, and 14.5 mA cm-2 for PBT, PFBT, and PDFBT, respectively). Also, the introduction of F atoms on conjugated backbones affects the recombination kinetics by suppressing bimolecular recombination, thereby improving the fill factor (0.41, 0.68, and 0.69 for PBT, PFBT, and PDFBT, respectively). Consequently, the PCE of PSCs reached 7.3% without any additional treatment (annealing, solvent additive, etc.) in the polymer containing difluorinated BT (PDFBT) that is much higher than nonfluorinated BT (PBT ∼ 1%) and monofluorinated BT (PFBT ∼ 6%).

Effect of revascularization strategy in patients with acute myocardial infarction and renal insufficiency with multivessel disease.

BACKGROUND/AIMS: The aim of this study was to compare the risk of complications and outcome between infarct-related artery (IRA)-only revascularization and multivessel (MV) revascularization in patients with acute myocardial infarction (MI) with renal insufficiency and MV disease. METHODS: A total of 1,031 acute MI patients with renal insufficiency and MV disease who were registered in the Korea Working Group on Myocardial Infarction were enrolled. They were divided into two groups (IRA-only revascularization group, n = 404; MV revascularization group, n = 627), and investigated the cumulative incidence of major adverse cardiac events (MACE) and the incidence of complications after percutaneous coronary intervention (PCI). RESULTS: Complications after PCI occurred in 19.9% of all patients (206/1,031). Complications after PCI occurred more frequently in the MV revascularization group compared with the IRA-only revascularization group (20.1% [126/627] vs. 15.3% [62/404], respectively; p = 0.029]. The overall in-hospital mortality rate was 6.3%, and there was no significant difference between the groups (5.2% in the IRA-only revascularization group vs. 7.0% in the MV revascularization group; p = 0.241). The total incidence of MACE was 11.1%, and there was no significant difference between the groups (11.6% in the IRA-only revascularization group vs. 10.7% in the MV revascularization group; p = 0.636). CONCLUSIONS: The incidence of complications after PCI was significantly lower in the IRA-only revascularization group compared with the MV revascularization group. However, there were no significant difference in the 12-month outcomes between groups in patients with acute MI and renal insufficiency with MV disease.

One-year clinical impact of cardiac arrest in patients with first onset acute ST-segment elevation myocardial infarction.

BACKGROUND: Cardiac arrest complicating acute ST elevation myocardial infarction (STEMI) is known to be associated with increased in-hospital mortality. However, little is known about the long-term outcomes after cardiac arrest complicating first onset STEMI in contemporary percutaneous coronary intervention (PCI) era. METHODS: We analyzed 7942 consecutive patients who were diagnosed with STEMI and had no previous history of MI. They were divided into two groups according to the presence of cardiac arrest (group I, patients with cardiac arrest; n=481, group II, patients without cardiac arrest; n=7641). RESULTS: In a stepwise multivariate model, previous history of chronic kidney disease, high serum level of glucose and low high density lipoprotein-cholesterol was an independent predictor of cardiac arrest complicating STEMI. Group I had significantly higher in-hospital mortality (adjusted hazard ratio [HR] 3.06, 95% confidence interval [CI] 2.08-4.51, p<0.001) and 30-day mortality after hospital discharge (adjusted HR 2.92, 95% CI 1.86-4.58, log-rank p<0.001). However, there was no significant increase in mortality beyond 30 days (6-month, adjusted HR 1.46, 95% CI 0.45-4.77, log rank p=0.382; 1-year, adjusted HR 1.84, 95% CI 0.83-4.05, log-rank p=0.107). Also, there were no significant differences in 6-month and 1-year major adverse cardiac events in 30-day survivors. Performing PCI was associated with decreased 12-month mortality in 30-day survivors. CONCLUSIONS: Although patients with cardiac arrest complicating first onset STEMI had higher in-hospital and 30-day mortality after hospital discharge, cardiac arrest itself did not have any residual impact on mortality as well as clinical outcomes.

Characteristics, in-hospital and long-term clinical outcomes of nonagenarian compared with octogenarian acute myocardial infarction patients.

We compared clinical characteristics, management, and clinical outcomes of nonagenarian acute myocardial infarction (AMI) patients (n=270, 92.3 ± 2.3 yr old) with octogenarian AMI patients (n=2,145, 83.5 ± 2.7 yr old) enrolled in Korean AMI Registry (KAMIR). Nonagenarians were less likely to have hypertension, diabetes and less likely to be prescribed with beta-blockers, statins, and glycoprotein IIb/IIIa inhibitors compared with octogenarians. Although percutaneous coronary intervention (PCI) was preferred in octogenarians than nonagenarians, the success rate of PCI between the two groups was comparable. In-hospital mortality, the composite of in-hospital adverse outcomes and one year mortality were higher in nonagenarians than in octogenarians. However, the composite of the one year major adverse cardiac events (MACEs) was comparable between the two groups without differences in MI or re-PCI rate. PCI improved 1-yr mortality (adjusted hazard ratio [HR], 0.50; 95% confidence interval [CI], 0.36-0.69, P<0.001) and MACEs (adjusted HR, 0.47; 95% CI, 0.37-0.61, P<0.001) without significant complications both in nonagenarians and octogenarians. In conclusion, nonagenarians had similar 1-yr MACEs rates despite of higher in-hospital and 1-yr mortality compared with octogenarian AMI patients. PCI in nonagenarian AMI patients was associated to better 1-yr clinical outcomes.

The association of socioeconomic status with three-year clinical outcomes in patients with acute myocardial infarction who underwent percutaneous coronary intervention.

The aim of this study was to evaluate whether the clinical outcomes were associated with socioeconomic status (SES) in patients with acute myocardial infarction (AMI) who underwent percutaneous coronary intervention (PCI). The author analyzed 2,358 patients (64.9 ± 12.3 yr old, 71.5% male) hospitalized with AMI between November 2005 and June 2010. SES was measured by the self-reported education (years of schooling), the residential address (social deprivation index), and the national health insurance status (medical aid beneficiaries). Sequential multivariable modeling assessed the relationship of SES factors with 3-yr major adverse cardiovascular events (MACEs) and mortality after the adjustment for demographic and clinical factors. During the 3-yr follow-up, 630 (26.7%) MACEs and 322 (13.7%) all-cause deaths occurred in 2,358 patients. In multivariate Cox proportional hazards regression modeling, the only lower education of SES variables was associated with MACEs (hazard ratio [HR], 1.41; 95% confidence interval [CI], 1.04-1.91) and mortality (HR, 1.93; 95% CI, 1.16-3.20) in the patients with AMI who underwent PCI. The study results indicate that the lower education is a significant associated factor to increased poor clinical outcomes in patients with AMI who underwent PCI.