Self-Trapped, Thermally Equilibrated Delayed Fluorescence Enables Low-Reabsorption Luminescent Solar Concentrators Based on Gold-Doped Silver Nanoclusters.

Reabsorption-free luminescent solar concentrators (LSCs) are crucial ingredients for photovoltaic windows. Atomically precise metal nanoclusters (NCs) with large Stokes-shifted photoluminescence (PL) hold great promise for applications in LSCs. However, a fundamental understanding of the PL mechanism, particularly on the excited-state interaction and exciton kinetics, is still lacking. Herein, we studied the exciton-phonon coupling and singlet/triplet exciton dynamics for gold-doped silver NCs in a solid matrix. Following photoexcitation, the excitons can be self-trapped via strong exciton-phonon coupling. Subsequently, rapid thermal equilibration between the singlet and triplet states occurs due to the coexistence of small energy splitting and spin-orbit coupling. Finally, broadband delayed fluorescence with a large Stokes shift can be generated, namely, self-trapped, thermally equilibrated delayed fluorescence (ST-TEDF). Benefiting from superior ST-TEDF, we demonstrated efficient LSCs with minimized reabsorption.

Editorial for focus on manipulations of atomic and molecular layers and its applications in energy, environment sciences and optoelectronic devices.

This Focus aims at showcasing the significance of manipulating atomic and molecular layers for various applications. To this end, this Focus collects 15 original research papers featuring the applications of atomic layer deposition, chemical vapor deposition, wet chemistry, and some other methods for manipulations of atomic and molecular layers in lithium-ion batteries, supercapacitors, catalysis, field-effect transistors, optoelectronics, and others.

Effects of bendable P3CT polymers layer on the photovoltaic performance of perovskite solar cells.

We report on the formation of bendable and edge-on poly[3-(4-carboxybutyl)thiophene-2,5-diyl] (P3CT) polymers thin layer used as a hole modification layer (HML) in the inverted perovskite solar cell. The aggregations of 2D layer-like P3CT polymers in dimethylformamide (DMF) solution can be formed via aromaticπ-πstacking interactions and/or hydrogen-bonding interactions with the different concentration from 0.01 to 0.02 wt%, which highly influences the photovoltaic performance of the inverted perovskite solar cells. The atomic-force microscopic images and water droplet contact angle images show that the P3CT polymers modify the surface properties of the transparent conductive substrate and thereby dominating the formation of perovskite crystalline thin films, which play important roles in the highly efficient and stable perovskite solar cells. It is noted that theVOC(JSC) of the encapsulated solar cells values are maintained to be higher than 1.115 V (22 mA cm-2) after 104 d when an optimizedπ-πstacked and hydrogen-bonded P3CT polymer is used as the HML. On the other hand, the solar cell showed a high long-term stability by maintaining 85% of the initial power conversion efficiency in the ambient air for 103 d.

Multiple Nucleocapsid Structural Forms of Shrimp White Spot Syndrome Virus Suggests a Novel Viral Morphogenetic Pathway.

White spot syndrome virus (WSSV) is a very large dsDNA virus. The accepted shape of the WSSV virion has been as ellipsoidal, with a tail-like extension. However, due to the scarcity of reliable references, the pathogenesis and morphogenesis of WSSV are not well understood. Here, we used transmission electron microscopy (TEM) and cryogenic electron microscopy (Cryo-EM) to address some knowledge gaps. We concluded that mature WSSV virions with a stout oval-like shape do not have tail-like extensions. Furthermore, there were two distinct ends in WSSV nucleocapsids: a portal cap and a closed base. A C14 symmetric structure of the WSSV nucleocapsid was also proposed, according to our Cryo-EM map. Immunoelectron microscopy (IEM) revealed that VP664 proteins, the main components of the 14 assembly units, form a ring-like architecture. Moreover, WSSV nucleocapsids were also observed to undergo unique helical dissociation. Based on these new results, we propose a novel morphogenetic pathway of WSSV.

Effects of drying time on the formation of merged and soft MAPbI3 grains and their photovoltaic responses.

The grain sizes of soft CH3NH3PbI3 (MAPbI3) thin films and the atomic contact strength at the MAPbI3/P3CT-Na interface are manipulated by varying the drying time of the saturated MAPbI3 precursor solutions, which influences the device performance and lifespan of the resultant inverted perovskite photovoltaic cells. The atomic-force microscopy images, cross-sectional scanning electron microscopy images, photoluminescence spectra and absorbance spectra show that the increased short-circuit current density (J SC) and increased fill factor (FF) are mainly due to the formation of merged MAPbI3 grains. Besides, the open-circuit voltage (V OC) of the encapsulated photovoltaic cells largely increases from 1.01 V to 1.15 V, thereby increasing the power conversion efficiency from 17.89% to 19.55% after 30 days, which can be explained as due to the increased carrier density of the MAPbI3 crystalline thin film. It is noted that the use of the optimized drying time during the spin coating process results in the formation of merged MAPbI3 grains while keeping the contact quality at the MAPbI3/P3CT-Na interface, which boosts the device performance and lifespan of the resultant perovskite photovoltaic cells.

QRS Fragmentation in Preserved Ejection Fraction Heart Failure: Functional Insights, Pathological Correlates, and Prognosis.

Background Fragmented QRS (fQRS) morphology as a surrogate marker of the possible presence of myocardial scarring has been shown to confer a higher risk in patients with reduced ejection fraction heart failure. We aimed to investigate the pathophysiological correlates and prognostic implications of fQRS in patients with heart failure with preserved ejection fraction (HFpEF). Methods and Results We consecutively studied 960 patients with HFpEF (76.4±12.7 years, men: 37.2%). fQRS was assessed using a body surface ECG during hospitalization. QRS morphology was available and classified into 3 categories among 960 subjects with HFpEF as non-fQRS, inferior fQRS, and anterior/lateral fQRS groups. Despite comparable clinical features in most baseline demographics among the 3 fQRS categories, anterior/lateral fQRS showed significantly higher B-type natriuretic peptide/troponin levels (both P<0.001), with both the inferior and anterior/lateral fQRS HFpEF groups demonstrating a higher degree of unfavorable cardiac remodeling, greater extent of myocardial perfusion defect, and slower coronary flow phenomenon (all P<0.05). Patients with anterior/lateral fQRS HFpEF exhibited significantly altered cardiac structure/function and more impaired diastolic indices (all P<0.05). During a median of 657 days follow-up, the presence of anterior/lateral fQRS conferred a doubled HF re-admission risk (adjusted hazard ratio 1.90, P<0.001), with both inferior and anterior/lateral fQRS having a higher risk of cardiovascular and all-cause death (all P<0.05) by using Cox regression models. Conclusions The presence of fQRS in HFpEF was associated with more extensive myocardial perfusion defects and worsened mechanics, which possibly denotes a more severe involvement of cardiac damage. Early recognition in such patients with HFpEF likely benefits from targeted therapeutic interventions.

Dislocation characterization inc-plane GaN epitaxial layers on 6 inch Si wafer with a fast second-harmonic generation intensity mapping technique.

Second harmonic generation (SHG) intensity, Raman scattering stress, photoluminescence and reflected interference pattern are used to determine the distributions of threading dislocations (TDs) and horizontal dislocations (HDs) in thec-plane GaN epitaxial layers on 6 inch Si wafer which is a structure of high electron mobility transistor (HEMT). The Raman scattering spectra show that the TD and HD result in the tensile stress and compressive stress in the GaN epitaxial layers, respectively. Besides, the SHG intensity is confirmed that to be proportional to the stress value of GaN epitaxial layers, which explains the spatial distribution of SHG intensity for the first time. It is noted that the dislocation-mediated SHG intensity mapping image of the GaN epitaxial layers on 6 inch Si wafer can be obtained within 2 h, which can be used in the optimization of high-performance GaN based HEMTs.

Stable and efficient soft perovskite crystalline film based solar cells prepared with a facile encapsulation method.

The quasi Fermi level for electrons in a soft perovskite crystalline thin film and the contact qualities at the PCBM/perovskite and perovskite/P3CT-Na interfaces can be increased using a facile encapsulation method, which improves the device performance and stability of the resultant perovskite solar cells. In the encapsulated perovskite solar cells, the averaged open-circuit voltage (VOC) largely increases from 0.981 V to 1.090 V after 9 days mainly due to the increased quasi Fermi levels. Besides, the reflectance and photoluminescence (PL) spectra show improved contact qualities at the PCBM/perovskite and perovskite/P3CT-Na interfaces, which can be used to explain the increase in the short-circuit current density (JSC) from 21.68 mA cm-2 to 23.48 mA cm-2 after the encapsulation process. Besides, nanosecond time-resolved PL and temperature-dependent PL spectra can be used to explain the increased VOC, which is mainly due to the increased shallow defect density and thereby increasing the exciton binding energy of the encapsulated perovskite sample. It is noted that the averaged power conversion efficiency (PCE) slowly decreases from 18.24% to 16.52% within 45 days.

Both epicardial and peri-aortic adipose tissue blunt heart rate recovery beyond body fat mass.

Background: Epicardial adipose tissue (EAT) as a marker of metabolic disorders has been shown to be closely associated with a variety of unfavorable cardiovascular events and cardiac arrhythmias. Data on regional-specific visceral adiposity outside the heart and its modulation on autonomic dysfunction, particularly heart rate recovery after exercise, remain obscure. Methods: We studied 156 consecutive subjects (mean age: 49.3 ± 8.0 years) who underwent annual health surveys and completed treadmill tests. Multi-detector computed tomography-based visceral adiposity, including EAT and peri-aortic fat (PAF) tissue, was quantified using dedicated software (Aquarius 3D Workstation, TeraRecon, San Mateo, CA, USA). We further correlated EAT and PAF with blood pressure and heart rate (HR) recovery information from an exercise treadmill test. Metabolic abnormalities were scored by anthropometrics in combination with biochemical data. Results: Increased EAT and PAF were both associated with a smaller reduction in systolic blood pressure during the hyperventilation stage before exercise compared to supine status (ß-coefficient (coef.): -0.19 and -0.23, respectively, both p < 0.05). Both visceral adipose tissue mediated an inverted relationship with heart rate recovery at 3 (EAT: ß-coef.: -0.3; PAF: ß-coef.: -0.36) and 6 min (EAT: ß-coef.: -0.32; PAF: ß-coef.: -0.34) after peak exercise, even after adjusting for baseline clinical variables and body fat composition (all p < 0.05). Conclusion: Excessive visceral adiposity, whether proximal or distal to the heart, may modulate the autonomic response by lowering the rate of HR recovery from exercise after accounting for clinical metabolic index. Cardiac autonomic dysfunction may partly explain the increase in cardiovascular morbidity and mortality related to both visceral fats.

Improving the photovoltaic performance of inverted perovskite solar cells via manipulating the molecular packing structure of PCBM.

In this study, the molecular packing structure of solution-processed phenyl-C61-butyric acid methyl ester (PCBM) thin film was manipulated by varying the volume ratio of chlorobenzene (CB) to bromobenzene (BrB) from 100:0 to 50:50, which largely influences the device performance of the PCBM/perovskite heterojunction solar cells. Absorbance spectra, photoluminescence spectra, atomic force microscopic images and contact angle images were used to investigate the molecular packing structure effects of the PCBM thin films on the device performance of the inverted perovskite solar cells. Our experimental results show that the formation of PCBM aggregates and the contact quality at the PCBM/perovksite interface significantly influence the open-circuit voltage, short-circuit current density and fill factor of the resultant solar cells simultaneously. It is noted that the PCE of the encapsulated inverted CH3NH3PbI3(MAPbI3) solar cells exhibited a stable and high power conversion efficiency of 18%.

Improving device performance of MAPbI3photovoltaic cells by manipulating the crystal orientation of tetragonal perovskites.

The properties of CH3NH3PbI3(MAPbI3) crystalline thin films and the device performance of highly efficient MAPbI3photovoltaic cells are investigated by varying the temperature of the antisolvent from 20 °C to 50 °C during the washing enhanced nucleation (WEN) process. The surface, structural, optoelectronic and defect properties of the perovskite thin films are characterized through atomic-force microscopy, X-ray diffractometry and photoluminescence spectrometry. The experimental results show that changing the temperature of the antisolvent during the WEN process can manipulate the MAPbI3crystalline thin films from the (110)-(002) complex phase to a (002) preferred phase. It is noted that the highest power conversion efficient of the inverted MAPbI3photovoltaic cells is 19.30%, mainly due to the increased carrier collection efficiency and reduced carrier recombination when the temperature of the antisolvent is 30 °C.

Insights on Distinct Left Atrial Remodeling Between Atrial Fibrillation and Heart Failure With Preserved Ejection Fraction.

Background: Heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF) commonly coexist with overlapping pathophysiology like left atrial (LA) remodeling, which might differ given different underlying mechanisms. Objectives: We sought to investigate the different patterns of LA wall remodeling in AF vs. HFpEF. Methods: We compared LA wall characteristics including wall volume (LAWV), wall thickness (LAWT), and wall thickness heterogeneity (LAWT[SD]) and LA structure, function among the controls (without AF or HFpEF, n = 115), HFpEF alone (n = 59), AF alone (n = 37), and HFpEF+AF (n = 38) groups using multi-detector computed tomography and echocardiography. Results: LA wall remodeling was most predominant and peak atrial longitudinal strain (PALS) was worst in HFpEF+AF patients as compared to the rest. Despite lower E/e' (9.8 ± 3.8 vs. 13.4 ± 6.4) yet comparable LA volume, LAWT and PALS in AF alone vs. HFpEF alone, LAWV [12.6 (11.6-15.3) vs. 12.0 (10.2-13.7); p = 0.01] and LAWT(SD) [0.68 (0.61-0.71) vs. 0.60 (0.56-0.65); p < 0.001] were significantly greater in AF alone vs. HFpEF alone even after multi-variate adjustment and propensity matching. After excluding the HFpEF+AF group, both LAWV and LAWT [SD] provided incremental values when added to PALS or LAVi (all p for net reclassification improvement <0.05) in discriminating AF alone, with LAWT[SD] yielding the largest C-statistic (0.78, 95% CI: 0.70-0.86) among all LA wall indices. Conclusions: Despite a similar extent of LA enlargement and dysfunction in HFpEF vs. AF alone, larger LAWV and LAWT [SD] can distinguish AF from HFpEF alone, suggesting the distinct underlying pathophysiological mechanism of LA remodeling in AF vs. HFpEF.

Safety and Efficacy of Submuscular Implantation With Resterilized Cardiac Implantable Electronic Device in Patients With Device Infection: A Retrospective Observational Study in Taiwan.

Background: Reuse of cardiac implantable electronic devices (CIEDs) can reduce the cost of using these expensive devices. However, whether resterilized CIEDs will increase the risk of reinfection in patients with previous device infection remains unknown. The aim of the present study is to compare the reinfection rates in patients who had initial CIED infection and underwent reimplantation of resterilized CIEDs or new devices. Methods: Data from patients with initial CIED infection who received debridement of the infected pocket and underwent reimplantation of new or resterilized CIEDs at MacKay Memorial Hospital, Taipei, Taiwan, between January 2014 and June 2019 were retrospectively analyzed. Patient characteristics, relapse rates of infection, and potential contributing factors to the infection risk were examined. Results: Twenty-seven patients with initial CIED infection and reimplanted new CIEDs (n = 11) or resterilized CIEDs (n = 16) were included. During the 2-year follow-up, there were 1 (9.1%) and 2 (12.5%) infection relapses in the new and resterilized CIED groups, respectively. No relapse occurred for either group if the lead was completely removed or cut short. The median duration between debridement and device reimplantation in patients with infection relapse vs patients without relapse was 97 vs 4.5 days for all included patients, and 97 vs 2 days and 50.5 vs 5.5 days for the new and resterilized CIED groups, respectively. Conclusions: Subpectoral reimplanting of resterilized CIEDs in patients with previous device infection is safe and efficacious. With delicate debridement and complete extraction of the leads, the CIED pocket infection relapse risk can be greatly decreased.

Two-Dimensional Self-Assembly of Boric Acid-Functionalized Graphene Quantum Dots: Tunable and Superior Optical Properties for Efficient Eco-Friendly Luminescent Solar Concentrators.

Carbon-based nanomaterials hold promise for eco-friendly alternatives to heavy-metal-containing quantum dots (QDs) in optoelectronic applications. Here, boric acid-functionalized graphene quantum dots (B-GQDs) were prepared using bottom-up molecular fusion based on nitrated pyrenes and boric acid. Such B-GQDs with crystalline graphitic structures and hydrogen-bonding functionalities would be suitable model systems for unraveling the photoluminescence (PL) mechanism, while serving as versatile building blocks for supramolecular self-assembly. Unlike conventional GQDs with multiple emissive states, the B-GQDs exhibited excitation-wavelength-independent, vibronic-coupled excitonic emission. Interestingly, their PL spectra can be tuned without largely sacrificing the quantum yield (QY) due to two-dimensional self-assembly. In addition, such B-GQDs in a polystyrene matrix possessed an ultrahigh QY (∼90%) and large exciton binding energy (∼300 meV). Benefiting from broadband absorption, ultrahigh QY, and long-wavelength emission, efficient laminated luminescent solar concentrators (100 × 100 × 6.3 mm3) were fabricated, yielding a high power conversion efficiency (1.4%).

Understanding the PEDOT:PSS, PTAA and P3CT-X Hole-Transport-Layer-Based Inverted Perovskite Solar Cells.

The power conversion efficiencies (PCEs) of metal-oxide-based regular perovskite solar cells have been higher than 25% for more than 2 years. Up to now, the PCEs of polymer-based inverted perovskite solar cells are widely lower than 23%. PEDOT:PSS thin films, modified PTAA thin films and P3CT thin films are widely used as the hole transport layer or hole modification layer of the highlyefficient inverted perovskite solar cells. Compared with regular perovskite solar cells, polymer-based inverted perovskite solar cells can be fabricated under relatively low temperatures. However, the intrinsic characteristics of carrier transportation in the two types of solar cells are different, which limits the photovoltaic performance of inverted perovskite solar cells. Thanks to the low activation energies for the formation of high-quality perovskite crystalline thin films, it is possible to manipulate the optoelectronic properties by controlling the crystal orientation with the different polymer-modified ITO/glass substrates. To achieve the higher PCE, the effects of polymer-modified ITO/glass substrates on the optoelectronic properties and the formation of perovskite crystalline thin films have to be completely understood simultaneously.

Improvement of interfacial contact for efficient PCBM/MAPbI3planar heterojunction solar cells with a binary antisolvent mixture treatment.

Atomic-force microscopic images, x-ray diffraction patterns, Urbach energies and photoluminescence quenching experiments show that the interfacial contact quality between the hydrophobic [6,6]-phenyl-C61-buttric acid methyl ester (PCBM) thin film and hydrophilic CH3NH3PbI3(MAPbI3) thin film can be effectively improved by using a binary antisolvent mixture (toluene:dichloromethane or chlorobenzene:dichloromethane) in the anti-solvent mixture-mediated nucleation process, which increases the averaged power conversion efficiency of the resultant PEDOT:PSS (P3CT-Na) thin film based MAPbI3solar cells from 13.18% (18.52%) to 13.80% (19.55%). Beside, the use of 10% dichloromethane (DCM) in the binary antisolvent mixture results in a nano-textured MAPbI3thin film with multicrystalline micrometer-sized grains and thereby increasing the short-circuit current density and fill factor (FF) of the resultant solar cells. It is noted that a remarkable FF of 80.33% is achieved, which can be used to explain the stable photovoltaic performance without additional encapsulations.

Aggregation-induced negative differential resistance in graphene oxide quantum dots.

Negative differential resistance (NDR) devices have attracted considerable interest due to their potential applications in switches, memory devices, and analog-to-digital converters. Modulation of the NDR is an essential issue for the development of NDR-based devices. In this study, we successfully synthesized graphene oxide quantum dots (GOQDs) using graphene oxide, cysteine, and H2O2. The current-voltage characteristics of the GOQDs exhibit a clear NDR in the ambient environment at room temperature. A peak-to-valley ratio as high as 4.7 has been achieved under an applied voltage sweep from -6 to 6 V. The behavior of the NDR and its corresponding peak-to-valley ratio can be controlled by adjusting the range of applied voltages, air pressure, and relative humidity. Also, the NDR is sensitive to the the concentration of H2O2 added in the synthesis. The charge carrier injection through the trapping states, induced by the GOQD aggregation, could be responsible for the NDR behavior in GOQDs.

Efficiency improvement of P3CT-Na based MAPbI3solar cells with a simple wetting process.

The averaged power conversion efficiency of polyelectrolytes (P3CT-Na) based MAPbI3solar cells can be increased from 14.94% to 17.46% with a wetting method before the spin-coating process of MAPbI3precursor solutions. The effects of the wetting process on the surface, structural, optical and excitonic properties of MAPbI3thin films are investigated by using the atomic-force microscopic images, x-ray diffraction patterns, transmittance spectra, photoluminescence spectra and Raman scattering spectra. The experimental results show that the wetting process of MAPbI3precursor solution on top of the P3CT-Na/ITO/glass substrate can be used to manipulate the molecular packing structure of the P3CT-Na thin film, which determines the formation of MAPbI3thin films.

19% Efficient P3CT-Na Based MAPbI3 Solar Cells with a Simple Double-Filtering Process.

A high-efficiency inverted-type CH3NH3PbI3 (MAPbI3) solar cell was fabricated by using a ultrathin poly[3-(4-carboxybutyl)thiophene-2,5-diyl]-Na (P3CT-Na) film as the hole transport layer. The averaged power conversion efficiency (PCE) can be largely increased from 11.72 to 18.92% with a double-filtering process of the P3CT-Na solution mainly due to the increase in short-circuit current density (JSC) from 19.43 to 23.88 mA/cm2, which means that the molecular packing structure of P3CT-Na thin film can influence the formation of the MAPbI3 thin film and the contact quality at the MAPbI3/P3CT-Na interface. Zeta potentials, atomic-force microscopic images, absorbance spectra, photoluminescence spectra, X-ray diffraction patterns, and Raman scattering spectra are used to understand the improvement in the JSC. Besides, the light intensity-dependent and wavelength-dependent photovoltaic performance of the MAPbI3 solar cells shows that the P3CT-Na thin film is not only used as the hole transport layer but also plays an important role during the formation of a high-quality MAPbI3 thin film. It is noted that the PCE values of the best P3CT-Na based MAPbI3 solar cell are higher than 30% in the yellow-to-near infrared wavelength range under low light intensities. On the other hand, it is predicted that the double-filtering method can be readily used to increase the PCE of polymer based solar cells.

Utilizing host-guest interaction enables the simultaneous enhancement of the quantum yield and Stokes shift in organosilane-functionalized, nitrogen-containing carbon dots for laminated luminescent solar concentrators.

Solar energy can be harvested using luminescent solar concentrators (LSCs) incorporated with edge-mounted solar cells without sacrificing their see-through visibility, thus facilitating the development of solar windows. Eco-friendly carbon dots (CDs) are promising alternatives to heavy-metal-containing quantum dots in LSC applications. Unfortunately, their solid-state quantum yield (QY) at high optical density (required by laminated LSCs) is still low (<30%) and the Stokes shift is only moderate (<100 nm). Here, we studied the host-guest interaction between aminosilane-functionalized, nitrogen-containing CDs (Si-NCDs) and a silica matrix for preparing efficient laminated LSCs. We found that a sol-gel-derived silica matrix with vacuum treatment can efficiently suppress the direct nonradiative transition of the absorbing states and selectively enhance the long-wavelength-emitting surface states. Therefore, the formed Si-NCDs@silica composites simultaneously exhibited high QYs (>60%) and large Stokes shifts (>200 nm) even at a high loading content (∼10 wt%), while still exhibiting high optical transparency. Moreover, unlike conventional QY reduction upon increasing the excitation wavelengths, such high QY values can be maintained over all excitation wavelengths in the absorption region. Benefiting from these photophysical properties, efficient laminated LSCs were simply prepared, yielding a high optical efficiency of ∼4.4%.