Organoboron molecules and polymers for organic solar cell applications.

Organic solar cells (OSCs) are emerging as a new photovoltaic technology with the great advantages of low cost, light-weight, flexibility and semi-transparency. They are promising for portable energy-conversion products and building-integrated photovoltaics. Organoboron chemistry offers an important toolbox to design novel organic/polymer optoelectronic materials and to tune their optoelectronic properties for OSC applications. At present, organoboron small molecules and polymers have become an important class of organic photovoltaic materials. Power conversion efficiencies (PCEs) of 16% and 14% have been realized with organoboron polymer electron donors and electron acceptors, respectively. In this review, we summarize the research progress in various kinds of organoboron photovoltaic materials for OSC applications, including organoboron small molecular electron donors, organoboron small molecular electron acceptors, organoboron polymer electron donors and organoboron polymer electron acceptors. This review also discusses how to tune their opto-electronic properties and active layer morphology for enhancing OSC device performance. We also offer our insight into the opportunities and challenges in improving the OSC device performance of organoboron photovoltaic materials.

A New Polymer Electron Acceptor Based on Thiophene-S,S-dioxide Unit for Organic Photovoltaics.

For polymer solar cells (PSCs), efficient polymer electron acceptors are always based on strong electron-withdrawing imide unit or boron-nitrogen coordinative bond (B←N). In this paper, a new polymer electron acceptor based on thiophene-S,S-dioxide (TDO) unit is reported. The polymer electron acceptor, PBDT-TDO, consists of alternating TDO unit and 4,8-bis(alkylthienyl)-2-yl]benzo[1,2-b:4,5-b']dithiophene (BDT) unit. For comparison, a control polymer with alternating BDT unit and thiophene unit has also been synthesized. Replacing thiophene unit with TDO unit in the polymer backbone leads to large downshift of lowest unoccupied molecular orbital/highest occupied molecular orbital energy levels by 0.9 eV/0.4 eV, which is attributed to the dearomatization and electron deficiency of TDO unit. The replacement also leads to redshift of absorption spectra by ≈110 nm. PSC device with PBDT-TDO as the electron acceptor shows photovoltaic response with the preliminary power conversion efficiency of 0.64%. This work suggests a new approach to design polymer electron acceptors using the TDO unit.

Solution-Processable Hyperbranched Conjugated Polymer Nanoparticles Based on C3h -Symmetric Benzotrithiophene for Polymer Solar Cells.

The development of photovoltaic polymers based on C3h -symmetric benzotrithiophene (C3h -BTT), an analogue of the well-known benzodithiophene (BDT) donor unit, has been severely limited due to difficult processability. Here the authors report the preparation of solution-processable C3h -BTT-based hyperbranched conjugated polymer nanoparticles (BTT-HCPNs) with tunable particle sizes via Stille miniemulsion polymerization. Compared with the corresponding star-shaped small molecule (C3h -BTT core with three diketopyrrolopyrrole arms, BTT-3DPP) with a wide bandgap (1.83 eV), both BTT-HCPNs show strong aggregation even in dilute solutions, leading to much-extended absorption (up to ≈1000 nm) and lower bandgaps (1.38 eV). The larger BTT-HCPN particle exhibits stronger aggregation and more extended absorption than the smaller one. As a result, solar cells fabricated from BTT-HCPNs/PC71 BM solutions show a power conversion efficiency up to 1.51% after DIO additive treatment, much higher than that of BTT-3DPP (0.31%).

Triple-crosslinked double-network alginate/dextran/dendrimer hydrogel with tunable mechanical and adhesive properties: A potential candidate for sutureless keratoplasty.

An ideal adhesive hydrogel must possess high adhesion to the native tissue, biocompatibility, eligible biodegradability, and good mechanical compliance with the substrate tissues. We constructed an interpenetrating double-network hydrogel containing polysaccharides (alginate and dextran) and nanosized spherical dendrimer by both physical and chemical crosslinking, thus endowing the hydrogel with a broad range of mechanical properties, adhesive properties, and biological functions. The double-network hydrogel has moderate pore sizes and swelling properties. The chelation of calcium ions significantly enhances the tensile and compressive properties. The incorporation of dendrimer improves both the mechanical and adhesive properties. This multicomponent interpenetrating network hydrogel has excellent biocompatibility, tunable mechanical and adhesive properties, and satisfied multi-functions to meet the complex requirements of wound healing and tissue engineering. The hydrogel exhibits promising corneal adhesion capabilities in vitro, potentially supplanting the need for sutures in corneal stromal surgery and mitigating the risks associated with donor corneal damage and graft rejection during corneal transplantation. This novel polysaccharide and dendrimer hydrogel also shows good results in sutureless keratoplasty, with high efficiency and reliability. Based on the clinical requirements for tissue bonding and wound closure, the hydrogel provides insight into solving the mechanical properties and adhesive strength of tissue adhesives.

Red-emitting dendritic iridium(III) complexes for solution processable phosphorescent organic light-emitting diodes.

Functionalization of a red phosphorescent iridium(III) complex core surrounded by rigid polyphenylene dendrons with a hole-transporting triphenylamine surface allows to prevent the intermolecular aggregation-induced emission quenching, improves charge recombination, and therefore enhances photo- and electroluminescence efficiencies of dendrimer in solid state. These multifunctional shape-persistent dendrimers provide a new pathway to design highly efficient solution processable materials for phosphorescent organic light-emitting diodes (PhOLEDs).

[Kirschner wire combined with PEEK anchor for the treatment of Wagstaffeâ ¡fracture].

OBJECTIVE: To explore clinical effect of Kirschner wire combined with PEEK anchor with thread to fix fibula bone block in WagstaffeⅡfracture. METHODS: From January 2018 to December 2020, 29 patients with WagstaffeⅡfracture of ankle joint were treated with Kirschner wire fixation of avulsed fibular bone block, PEEK with thread anchor repair and reinforcement, and plaster external fixation, including 18 males and 11 females, aged from 27 to 69 years old with an average of (46.3±10.2) years old. All of them were unilateral operations, and the time from injury to operation ranged from 3 to 5 days with an average of(4.05±0.63) days. Clinical efficacy was evaluated by using American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot functional scoring system and visual analogue scaleat scoring system before and after operation at 6 months. RESULTS: All patients were followed up from 6 to 12 months with an average of (9.7±2.1) months. Two patients occurred pain of ankle joint during walking, which was relieved after strengthening rehabilitation exercise and anti-nflammatory and analgesic drug treatment. AOFAS score was incrased from(62.16±19.73) preoperativyly to(91.35±6.37) at 6 months after operation (t=5.51, P<0.01);15 patients got excellent results, 12 moderate and 2 good. VAS was decreased (5.91±1.57) preoperativly to (0.41±0.37) at 6 months after operation(t=10.54, P<0.01). CONCLUSION: Kirschner wire combined with PEEK anchor with thread to fix fibula bone block in WagstaffeⅡfracture strengthen repair of inferior tibiofibular syndesmosis ligament and anterior talofibular ligament, and effectively relieved ankle joint pain, obtain good function recovery, the avulsion fracture block was fixed securely, and receive good clinical effect.

Microplastics in 48 wastewater treatment plants reveal regional differences in physical characteristics and shape-dependent removal in the transition zone between North and South China.

This study investigated the physical characteristics and removal efficiency of microplastics in wastewater from regions with different climatic conditions and economic development levels. Microplastics with different shapes and sizes were analyzed from the influent and effluent of 48 wastewater treatment plants in three regions of Shaanxi Province (China). Results indicated that the abundance of microplastics in the influent samples was higher in the region with less regional water resources. However, the per capita microplastics emissions was higher in the region with higher economic development level. There were less fibers and more foams and beads in the more developed region. The removal efficiency of microplastics was related to their shape and size. Particularly, the removal efficiency showed a significant negative correlation with the percentage of foams, while it had a significant positive relationship with the proportions of films and fibers. The highest removal efficiency was obtained when the size of microplastics was ranged from 0.5 to 1.0 mm. This study suggests, compared to improving the removal efficiency of microplastics, that reducing the input at source is a more scientific and promising method.

Tuning the donor-acceptor strength of low-bandgap platinum-acetylide polymers for near-infrared photovoltaic applications.

Two near-infrared (NIR) absorbing metallopolyynes of platinum (P1 and P2) functionalized with a weakly electron-donating fluorene unit and two strong electron acceptors (viz. benzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) and [1,2,5]thiadiazolo[3,4-i]dibenzo[a,c]phenazine) were synthesized and applied for NIR photovoltaic applications. With these designed weak donor-strong acceptor electronic traits, these metallopolymers possess narrow bandgaps of 1.54 and 1.65 eV and a low HOMO level of about 5.50 eV, thus inducing a power conversion efficiency up to 1% for bulk heterojunction solar cells at the NIR wavelength.

Development of L-carnosine functionalized iron oxide nanoparticles loaded with dexamethasone for simultaneous therapeutic potential of blood brain barrier crossing and ischemic stroke treatment.

The development of suitable drug delivery carriers is significant in biomedical applications to improve the therapeutic efficiency. Recent progress in nanotechnological fields, paved the way for the formulation of variety of drug carriers. The brain disorders such as ischemic stroke, brain cancer, and CNS disorders were poorly treated due to the presence of blood brain barrier that hinders the passage of drugs to the brain. Hence, the formulated drugs should have the ability to cross the blood-brain barrier (BBB) for ischemic stroke treatment. In the present work, we have synthesized PLGA functionalized magnetic Fe3O4 nanoparticle (MNP) with L-carnosine peptide (LMNP) composite loaded with dexamethasone (dm@LMNP) and demonstrated as efficient drug delivery platform for simultaneous BBB crossing and treatment of ischemic stroke. The surface morphology, particles size and zeta potential of the prepared material was studied from SEM, PSD, PDI and TEM analyses. The drug loading of dexamethasone in LMNP (dm@LMNP) vesicles was found to be 95.6 ± 0.2%. The in vitro drug release kinetics displayed that prepared composited LMNP material provides controlled and sustainable releasing efficiency at pH 7.4 and 5.8 when compared to the PLGA NPs and free dexamethasone drug molecules. The cytotoxicity and the biocompatibility test results were found to be satisfactory. The L-carnosine loaded nano-formulation has been greatly leads to effective BBB crossing to access the brain tissues. These results showed that the Fe3O4 nanoparticles/PLGA polymer can be used as an effective drug carrier for the treatment of stroke and simultaneous blood brain barrier crossing.

The Need for Ocular Protection for Health Care Workers During SARS-CoV-2 Outbreak and a Hypothesis for a Potential Personal Protective Equipment.

SARS-CoV-2 is a coronavirus with high infectivity and has caused dramatic pressure on health systems all over the world. Appropriate personal protection for medical staffs is critical. For ocular protection, there is ongoing hot debate and concern for potential ocular transmission of SARS-CoV-2. Ocular manifestations and positive detection of viral RNA in ocular samples were only reported in very small number of patients infected with SARS-CoV-2. However, health care workers need to face patients more closely and have higher risk of aerosol contamination. Thus, appropriate ocular protection for medical workers is still recommended by organizations such as WHO and American Academy of Ophthalmology. Although eye goggles provide excellent protection and are mandatory for medical practitioners with high risk of exposure, they are not ideal for common clinical practice, because they can disturb vision due to extensive formation of water droplets and frequently cause moderate to severe discomfort after longtime wearing, which have been reported to interfere with working status. For the majority of medical workers who don't deal with high risk patients, they are not advised to wear goggles in daily practice. However, they also face the risk of infection due to the presence of asymptomatic carriers. Especially in situations with high risk of ocular exposure, such as close physical examination, eye surgery, dental clinics and surgery, ocular protection may be needed. Griffithsin has been shown to directly bind to spike proteins and has anti-viral activity against a broad spectrum of viruses, including coronavirus. Griffithsin is found to inhibit the entry of SARS-CoV at relatively low concentration and is stable and non-toxic. SARS-CoV-2 and SARS-CoV share the same entry receptors and their spike proteins are similar in conformation. We hypothesize that contact lenses containing nanoparticles loaded with griffithsin may provide sufficient ocular protection for medical staffs without high risk of exposure during the outbreak period of SARS-CoV-2. If proven effective, griffithsin-loaded contact lens can be considered as a supplementary ocular protective equipment for medical workers who can tolerate well. The daily disposable contact lens should be applied as needed and refrain from extended wearing in order to reduce potential side effects.

Fluorescent switch constructed based on hemin-sensitive anionic conjugated polymer and its applications in DNA-related sensors.

Here, a fluorescent switch is constructed combining hemin, hemin aptamer, and a newly synthesized anionic conjugated polymer (ACP), poly(9,9-bis(6'-phosphatehexyl) fluorenealt-1,4-phenylene) sodium salt (PFHPNa/PFP). In the "off-state", the fluorescence of PFP is sensitively quenched by hemin, with a high K(sv) value of approximately 10(7). While in the "on-state", the formation of the aptamer/hemin complex recovers the fluorescence intensity. The fluorescent switch is sensitive and selective to hemin. To testify the universality and practicality of the fluorescent switch, a series of label-free DNA-related sensing platforms are developed, containing three DNA sensing strategies and one ATP recognition strategy. The fluorescent switch developed is simple, sensitive, and universal, which extends applications of the anionic conjugated polymers.

Non-triggered sequential-release liposomes enhance anti-breast cancer efficacy of STS and celastrol-based microemulsion.

A codelivery system that sequentially releases its contents is an effective strategy to enhance anticancer efficacy. Here, we fabricated multicomponent-based liposomes (T/CM-L) loaded with sodium tanshinone IIA sulfonate (STS) and a small-sized microemulsion of celastrol (CM), which shows synergistic anti-breast cancer activity through the initial release of STS for modulation of the tumor microenvironment, and subsequent release of CM (and its payloads) for eradication of tumor tissues. In vitro studies exhibited that T/CM-L induced massive apoptosis of MCF-7 cells, indicating a coordinated cytotoxicity against cancer cells. Once the liposomes had accumulated at the tumor site, STS was released from T/CM-L in the first place to repair abnormal vessels as well as to decrease the level of fibroblasts. Owing to the barriers of the microemulsion and the liposomes, the celastrol was then unloaded at a moderate rate to kill the tumor cells, which resulted in the shrinkage of the tumor size. Furthermore, T/CM-L displayed diminished systemic toxicity compared to celastrol used alone. Our work offers a novel strategy for combination anticancer treatment and holds promising potential not only for breast cancer treatment, but also for the treatment of other solid tumors.

Thin film fabricated from solution-dispersible porous hyperbranched conjugated polymer nanoparticles without surfactants.

Porous hyperbranched conjugated polymer nanoparticles with an average particle size of 20-60 nm and a specific surface area of 225 m(2) g(-1) have been prepared through Suzuki polymerization in a miniemulsion, which could be stably dispersed in common organic solvents after complete removal of surfactants. Furthermore, a simple spin-coating method for the preparation of homogeneous transparent thin films of the nanoparticle has been developed. Bright blue emission of the porous nanoparticle films could be reversibly quenched by nitroaromatics with enhanced sensitivity compared to dense films of the linear conjugated polymer analogue.

Interface-induced crystalline ordering and favorable morphology for efficient annealing-free poly(3-hexylthiophene): fullerene derivative solar cells.

A simple approach to fabricate high-efficiency annealing-free poly(3-hexylthiophene): [6,6]-phenyl C(61)-butyric acid methyl ester (P3HT:PCBM) solar cells is reported by using p-type CuI to substitute PEDOT:PSS as anode buffer layer. It is found that the P3HT:PCBM blend films deposited on CuI surface show different orientation of crystalline P3HT domains and phase separation from those deposited on PEDOT:PSS surface. A nanoscale phase separation of P3HT and PCBM with domain sizes about 10-30 nm is formed for the P3HT:PCBM blend films deposited on CuI surface. Absorption and grazing incidence X-ray diffraction (GIXRD) experiments indicate that the CuI layer not only induces the self-organization of P3HT chains into well-ordered structure but also results in the vertical orientation of π-π stacking planes of P3HT with respect to the substrate which is favorable for the hole collection in polymer solar cells. Hole-transport investigation discloses that hole mobility of the as-spincast P3HT:PCBM blend film on CuI surface is increased with 3 orders of magnitude compared to the P3HT:PCBM film deposited on PEDOT:PSS. A power conversion efficiency of 3.1% for the as-spincast P3HT:PCBM solar cell with CuI buffer layer is about 4-fold enhancement compared to 0.83% of the control device with PEDOT:PSS, and is comparable to the reported P3HT:PCBM solar cells subjected to post thermal treatments. This work implies that interfacial engineering is a promising approach for manipulating morphology of active layer and can potentially simplify the process and shorten the fabrication time of polymer solar cells in low-cost roll-to-roll manufacturing.

Spiro-linked hyperbranched architecture in electrophosphorescent conjugated polymers for tailoring triplet energy back transfer.

A spiro-linked hyperbranched architecture has been incorporated into electrophosphorescent conjugated polymers for the first time, aiming at simultaneously tailoring the intra- and intermolecular triplet energy back transfer from the phosphorescent guest to the conjugated polymer host. Based on a prototype with this unique structure, slower decay of triplet excitons, and 5-8 fold enhancement of device efficiencies are obtained compared with the conventional blending counterpart.

High-efficiency inverted polymer solar cells with transparent and work-function tunable MoO(3)-Al composite film as cathode buffer layer.

High-efficiency inverted polymer solar cells based on PCDTBT:PC(70)BM blend with the MoO(3)-Al composite film as the cathode buffer layer and the MoO(3)/Al as the anode have been demonstrated. A V(OC) of 0.88 V, a J(SC) of 10.88 mA cm(-2), a FF of 70.7% and a PCE of 6.77% are achieved. The MoO(3)-Al composite films are highly transparent with adjustable work functions which can be fine tuned based on the Al content in the composite, thus allowing us to optimize the interfacial property at cathode buffer layer/BHJ interfaces to reduce recombination loss and to improve the photovoltaic performance. This new approach has simplified the device fabrication and will render economizing in large scale applications.

High-efficiency single emissive layer white organic light-emitting diodes based on solution-processed dendritic host and new orange-emitting iridium complex.

An extremely high-efficiency solution-processed white organic light-emitting diode (WOLED) is successfully developed by simultaneously using an ideal dendritic host material and a novel efficient orange phosphorescent iridium complex. The optimized device exhibits forward-viewing efficiencies of 70.6 cd A(-1) , 26.0%, and 47.6 lm W(-1) at a luminance of 100 cd m(-2) , respectively, promising the low-cost solution-processed WOLEDs a bright future as the next generation of illumination sources.