Highly Stretchable Conjugated Polymer/Elastomer Blend Films with Sandwich Structure.

The physical blending of high-mobility conjugated polymers with ductile elastomers provides a simple way to realize high-performance stretchable films. However, how to control the morphology of the conjugated polymer and elastomer blend film and its response to mechanical fracture processes during stretching are not well understood. Herein, a sandwich structure is constructed in the blend film based on a conjugated polymer poly[(5-fluoro-2,1,3-benzothiadiazole-4,7-diyl)(4,4-dihexadecyl-4H-cyclopenta[2,1-b:3,4-b″]dithiophene-2,6-diyl)(6-fluoro-2,1,3-benzothiadiazole-4,7-diyl)(4,4-dihexadecyl-4H-cyclopenta[2,1-b:3,4-b″]dithiophene-2,6-diyl)] (PCDTFBT) and an elastomer polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS). The sandwich structure is composed of a PCDTFBT:SEBS mixed layer laminated with a PCDTFBT-rich layer at both the top and bottom surfaces. During stretching, the external strain energy can be effectively dissipated by the deformation of the crystalline PCDTFBT domains and amorphous SEBS phases and the recrystallization of the PCDTFBT chains. This endows the blend film with excellent ductility, with a large crack onset strain exceeding 1100%, and minimized the electrical degradation of the blend film at a large strain. This study indicates that the electrical and mechanical performance of conjugated polymer/elastomer blend films can be improved by manipulating their microstructure.

One-stone-for-two-birds strategy to attain beyond 25% perovskite solar cells.

Even though the perovskite solar cell has been so popular for its skyrocketing power conversion efficiency, its further development is still roadblocked by its overall performance, in particular long-term stability, large-area fabrication and stable module efficiency. In essence, the soft component and ionic-electronic nature of metal halide perovskites usually chaperonage large number of anion vacancy defects that act as recombination centers to decrease both the photovoltaic efficiency and operational stability. Herein, we report a one-stone-for-two-birds strategy in which both anion-fixation and associated undercoordinated-Pb passivation are in situ achieved during crystallization by using a single amidino-based ligand, namely 3-amidinopyridine, for metal-halide perovskite to overcome above challenges. The resultant devices attain a power conversion efficiency as high as 25.3% (certified at 24.8%) with substantially improved stability. Moreover, the device without encapsulation retained 92% of its initial efficiency after 5000 h exposure in ambient and the device with encapsulation retained 95% of its initial efficiency after >500 h working at the maximum power point under continuous light irradiation in ambient. It is expected this one-stone-for-two-birds strategy will benefit large-area fabrication that desires for simplicity.

Synergistic Crystallization and Passivation by a Single Molecular Additive for High-Performance Perovskite Solar Cells.

With its power conversion efficiency surpassing those of all other thin-film solar cells only a few years after its invention, the perovskite solar cell has become a superstar. Controlling the intermediate phase of crystallization is a key to obtaining high-quality perovskite films. Herein, a single molecule additive, N,N-dimethylimidodicarbonimidic diamide hydroiodide (DIAI), is incorporated into the perovskite precursor to eliminate the influence of intermediate phases. By taking advantage of the interaction of DIAI and dimethyl sulfoxide (DMSO), the intermediate phase FAI-PbI2 -DMSO complex is eliminated, and δ-FAPbI3 is entirely converted to the desired α-FAPbI3 during the crystallization step, resulting in enlarged grain size and improved crystalline quality. This is the first observation in the solution method that FAPbI3 can be obtained without an intermediate phase for high-performance perovskite solar cells. Furthermore, DIAI is effective at passivating surface defects, resulting in reduced defect density, increased carrier lifetime, and improved device efficiency and stability. The champion device achieves an efficiency of 24.13%. Furthermore, the bare device without any encapsulation maintains 94.1% of its initial efficiency after ambient exposure over 1000h. This work contributes a strategy of synergistic crystallization and passivation to directly form α-FAPbI3 from the precursor solution without the influence of intermediate impurities for high-performance perovskite applications.

Comparison of Anterior Capsule Polishing on the Rate of Neodymium: YAG Laser Capsulotomy After Two Multifocal Intraocular Lens Implantation.

Purpose: To compare the impact of anterior capsule polishing (ACP) during cataract surgery on the rate of neodymium: YAG (Nd: YAG) laser capsulotomy in pseudophakic eyes with two multifocal intraocular lenses (MIOLs). Methods: Data were collected on patients who underwent cataract surgery and implanted segmental refractive MIOLs (SBL-3, Lenstec) or diffracted MIOLs (AT LISA tri 839MP, Carl Zeiss Meditec). The participants were divided into ACP and non-ACP groups based on whether the anterior capsule was polished. The primary outcome measure was whether Nd: YAG capsulotomy was performed during the 3 years follow-up. We used Kaplan-Meier survival curves to determine the time from IOL implantation to Nd: YAG laser capsulotomy. Results: ACP and non-ACP groups comprised 70 and 60 eyes, respectively. One year postoperatively, 7.14% of ACP group eyes and 8.33% of non-ACP group required Nd: YAG laser capsulotomy (P > 0.99). After 2 years, it was 24.29 and 18.33%, respectively (P = 0.52), while after 3 years, it reached 30.0 and 28.33% (P = 0.85). No distinct difference existed in the probability of using Nd: YAG laser in both groups evaluated using Kaplan-Meier survival curves (P = 0.81). Patients with diffractive MIOLs (AT LISA tri 839MP) implantation were more likely to require Nd: YAG laser capsulotomy (P < 0.01). Conclusion: Polishing the anterior capsule had no remarkable effect on reducing the rate of Nd: YAG laser capsulotomy following phacoemulsification in MIOLs. Patients with diffractive MIOLs implantation had a high probability of requiring Nd: YAG laser capsulotomy.

Visual Performance Following Bilateral Implantation of Refractive Rotationally Asymmetric Bifocal Intraocular Lens (LS-313 MF30) or Apodized Diffractive Bifocal Intraocular Lens (ReSTOR SN6AD1).

PURPOSE: This study compared the clinical outcomes after cataract surgery with implantation of refractive rotationally asymmetric bifocal intraocular lens (IOL) (LS-313 MF30) and apodized diffractive bifocal IOL (ReSTOR SN6AD1). METHODS: This was a prospective, non-randomized, controlled study, where patients diagnosed with age-related cataracts were selected for phacoemulsification combined with bilateral IOL implantation. Based on the type of IOL voluntarily implanted, the patients were divided into two groups, ie, refractive and diffractive groups. In total, 30 cases (60 eyes) were in a refractive group, while 30 cases (60 eyes) were in diffractive group. Three months after surgery, we examined the uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), defocus curve, objective visual quality, and subjective questionnaire. RESULTS: Three months after surgery, the UIVA of the refractive group (0.18 ± 0.08) logMAR was better than that of the diffractive group (0.29 ± 0.16) logMAR (P < 0.05). No significant difference in UDVA and UNVA was noted between the two groups. For a 4mm pupil diameter, the intraocular and total eye aberration, higher-order aberration (HOA), coma, spherical aberration, and trefoil in the refractive group were significantly higher than those in diffractive group (P < 0.05). The intraocular modulation transfer function (MTF), intraocular strehl ratio (SR), total eye MTF, and total eye SR in the refractive group were lower than those in diffractive group (P < 0.05). No significant difference in glare incidence, spectacle independence rate, and patient satisfaction was observed between the two groups (P > 0.05). The halos incidence in the refractive group was lower than the diffractive group (P < 0.05). CONCLUSION: Both bifocal IOLs obtained satisfactory UDVA and UNVA, with higher patient satisfaction. Unlike the apodized diffractive bifocal IOL, the refractive rotationally asymmetric bifocal IOL yielded slightly better UIVA, lower halos incidence, whereas the apodized diffractive bifocal IOL showed a better objective visual quality.

Effective Phase-Alignment for 2D Halide Perovskites Incorporating Symmetric Diammonium Ion for Photovoltaics.

New structural type of 2D AA'n -1 Mn X3 n +1 type halide perovskites stabilized by symmetric diammonium cations has attracted research attention recently due to the short interlayer distance and better charge-transport for high-performance solar cells (PSCs). However, the distribution control of quantum wells (QWs) and its influence on optoelectronic properties are largely underexplored. Here effective phase-alignment is reported through dynamical control of film formation to improve charge transfer between quantum wells (QWs) for 2D perovskite (BDA)(MA)n -1 Pbn I3 n +1 (BDA = 1,4-butanediamine, 〈n〉 = 4) film. The in situ optical spectra reveal a significantly prolonged crystallization window during the perovskite deposition via additive strategy. It is found that finer thickness gradient by n values in the direction orthogonal to the substrate leads to more efficient charge transport between QWs and suppressed charge recombination in the additive-treated film. As a result, a power conversion efficiency of 14.4% is achieved, which is not only 21% higher than the control one without additive treatment, but also one of the high efficiencies of the low-n (n ≤ 4) AA'n -1 Mn X3 n +1 PSCs. Furthermore, the bare device retains 92% of its initial PCE without any encapsulation after ambient exposure for 1200 h.

Perovskite Solar Cells toward Eco-Friendly Printing.

Eco-friendly printing is important for mass manufacturing of thin-film photovoltaic (PV) devices to preserve human safety and the environment and to reduce energy consumption and capital expense. However, it is challenging for perovskite PVs due to the lack of eco-friendly solvents for ambient fast printing. In this study, we demonstrate for the first time an eco-friendly printing concept for high-performance perovskite solar cells. Both the perovskite and charge transport layers were fabricated from eco-friendly solvents via scalable fast blade coating under ambient conditions. The perovskite dynamic crystallization during blade coating investigated using in situ grazing incidence wide-angle X-ray scattering (GIWAXS) reveals a long sol-gel window prior to phase transformation and a strong interaction between the precursors and the eco-friendly solvents. The insights enable the achievement of high quality coatings for both the perovskite and charge transport layers by controlling film formation during scalable coating. The excellent optoelectronic properties of these coatings translate to a power conversion efficiency of 18.26% for eco-friendly printed solar cells, which is on par with the conventional devices fabricated via spin coating from toxic solvents under inert atmosphere. The eco-friendly printing paradigm presented in this work paves the way for future green and high-throughput fabrication on an industrial scale for perovskite PVs.

Ascorbic Acid Promotes the Stemness of Corneal Epithelial Stem/Progenitor Cells and Accelerates Epithelial Wound Healing in the Cornea.

High concentration of ascorbic acid (vitamin C) has been found in corneal epithelium of various species. However, the specific functions and mechanisms of ascorbic acid in the repair of corneal epithelium are not clear. In this study, it was found that ascorbic acid accelerates corneal epithelial wound healing in vivo in mouse. In addition, ascorbic acid enhanced the stemness of cultured mouse corneal epithelial stem/progenitor cells (TKE2) in vitro, as shown by elevated clone formation ability and increased expression of stemness markers (especially p63 and SOX2). The contribution of ascorbic acid on the stemness enhancement was not dependent on the promotion of Akt phosphorylation, as concluded by using Akt inhibitor, nor was the stemness found to be dependent on the regulation of oxidative stress, as seen by the use of two other antioxidants (GMEE and NAC). However, ascorbic acid was found to promote extracellular matrix (ECM) production, and by using two collagen synthesis inhibitors (AzC and CIS), the increased expression of p63 and SOX2 by ascorbic acid was decreased by around 50%, showing that the increased stemness by ascorbic acid can be attributed to its regulation of ECM components. Moreover, the expression of p63 and SOX2 was elevated when TKE2 cells were cultured on collagen I coated plates, a situation that mimics the in vivo situation as collagen I is the main component in the corneal stroma. This study shows direct therapeutic benefits of ascorbic acid on corneal epithelial wound healing and provides new insights into the mechanisms involved. Stem Cells Translational Medicine 2017;6:1356-1365.

Active Pedicle Epithelial Flap Transposition Combined with Amniotic Membrane Transplantation for Treatment of Nonhealing Corneal Ulcers.

Introduction. The objective was to evaluate the efficacy of active pedicle epithelial flap transposition combined with amniotic membrane transplantation (AMT) in treating nonhealing corneal ulcers. Material and Methods. Eleven patients (11 eyes) with nonhealing corneal ulcer who underwent the combined surgery were included. Postoperatively, ulcer healing time was detected by corneal fluorescein staining. Visual acuity, intraocular pressure, surgical complications, and recurrence were recorded. Corneal status was inspected by the laser scanning confocal microscopy and anterior segment optical coherence tomography (AS-OCT). Results. The primary diseases were herpes simplex keratitis (8 eyes), corneal graft ulcer (2 eyes), and Stevens-Johnson syndrome (1 eye). All epithelial flaps were intact following surgery, without shedding or displacement. Mean ulcer healing time was 10.8 ± 3.1 days, with a healing rate of 91%. Vision significantly improved from 1.70 to 0.82 log MAR (P = 0.001). A significant decrease in inflammatory cell infiltration and corneal stromal edema was revealed 2 months postoperatively by confocal microscopy and AS-OCT. Corneal ulcer recurred in 1 eye. None of the patients developed major complications. Conclusion. Active pedicle epithelial flap transposition combined with AMT is a simple and effective treatment for nonhealing corneal ulcers.