Achieving High Efficiency and Stability in Organic Photovoltaics with a Nanometer-Scale Twin p-i-n Structured Active Layer.

In pursuing high stability and power conversion efficiency for organic photovoltaics (OPVs), a sequential deposition (SD) approach to fabricate active layers with p-i-n structures (where p, i, and n represent the electron donor, mixed donor:acceptor, and electron acceptor regions, respectively, distinctively different from the bulk heterojunction (BHJ) structure) has emerged. Here, we present a novel approach that by incorporating two polymer donors, and , and one small-molecule acceptor, , into the active layer with sequential deposition, we formed a device with nanometer-scale twin p-i-n structured active layer. The twin p-i-n device involved first depositing a blend under layer and then a top layer and exhibited an improved power conversion efficiency (PCE) value of 18.

MoS Nanoflowers Grown on Plasma-Induced W-Anchored Graphene for Efficient and Stable H Production Through Seawater Electrolysis.

Herein, it is found that 3D transition metal dichalcogenide (TMD)-MoS nanoflowers-grown on 2D tungsten oxide-anchored graphene nanosheets (MoS @W-G) functions as a superior catalyst for the hydrogen evolution reaction (HER) under both acidic and alkaline conditions. The optimized weight ratio of MoS @W-G (MoS :W-G/1.5:1) in 0.

Ion accumulation-induced capacitance elevation in a microporous graphene-based supercapacitor.

High-performance porous 3D graphene-based supercapacitors are one of the most promising and challenging directions for future energy technologies. Microporous graphene has been synthesized by the pyrolysis method. The fabricated lightweight graphene with a few layers (FLG) has an ultra-high surface area of 2266 m g along with various-sized micropores.

Bubble-Channeling Electrophoresis of Honeycomb-Like Chitosan Composites.

A chitosan composite with a vertical array of pore channels is fabricated via an electrophoretic deposition (EPD) technique. The composite consists of chitosan and polyethylene glycol, as well as nanoparticles of silver oxide and silver. The formation of hydrogen bubbles during EPD renders a localized increase of hydroxyl ions that engenders the precipitation of chitosan.

Pentafluoropyridine functionalized novel heteroatom-doped with hierarchical porous 3D cross-linked graphene for supercapacitor applications.

The fabrication with high energy density and superior electrical/electrochemical properties of hierarchical porous 3D cross-linked graphene-based supercapacitors is one of the most urgent challenges for developing high-power energy supplies. We facilely synthesized a simple, eco-friendly, cost-effective heteroatoms (nitrogen, phosphorus, and fluorine) co-doped graphene oxide (NPFG) reduced by hydrothermal functionalization and freeze-drying approach with high specific surface areas and hierarchical pore structures. The effect of different heteroatoms doping on the energy storage performance of the synthesized reduced graphene oxide is investigated extensively.

High-Performance Organic Solar Cells Featuring Double Bulk Heterojunction Structures with Vertical-Gradient Selenium Heterocyclic Nonfullerene Acceptor Concentrations.

In this study, we prepared organic photovoltaics (OPVs) featuring an active layer comprising double bulk heterojunction (BHJ) structures, featuring binary blends of a polymer donor and concentration gradients of two small-molecule acceptors. After forming the first BHJ structure by spin-coating, the second BHJ layer was transfer-printed onto the first using polydimethylsiloxane stamps. A specially designed selenium heterocyclic small-molecule acceptor (Y6-Se-4Cl) was employed as the second acceptor in the BHJ.

High-Performance Organic Photovoltaics Incorporating an Active Layer with a Few Nanometer-Thick Third-Component Layer on a Binary Blend Layer.

In this paper, a universal approach toward constructing a new bilayer device architecture, a few-nanometer-thick third-component layer on a bulk-heterojunction (BHJ) binary blend layer, has been demonstrated in two different state-of-the-art organic photovoltaic (OPV) systems. Through a careful selection of a third component, the power conversion efficiency (PCE) of the device based on PM6/Y6/layered PTQ10 layered third-component structure was 16.8%, being higher than those of corresponding devices incorporating the PM6/Y6/PTQ10 BHJ ternary blend (16.

Incorporating Indium Selenide Nanosheets into a Polymer/Small Molecule Binary Blend Active Layer Enhances the Long-Term Stability and Performance of Its Organic Photovoltaics.

In this report, we demonstrated that the incorporation of 15 wt % two-dimensional transition-metal dichalcogenide materials indium selenide (InSe) nanosheets into a polymer (PM6)/small molecule (Y6) active layer not only increased its light absorption but also enhanced the long-term stability of the PM6/Y6/InSe ternary blend organic photovoltaic (OPV) devices. The power conversion efficiency (PCE) of the device was improved from 15.7 to 16.

Transparent Hole-Transporting Frameworks: A Unique Strategy to Design High-Performance Semitransparent Organic Photovoltaics.

Thanks to the nature of molecular orbitals, the absorption spectra of organic semiconductors are not continuous like those in traditional inorganic semiconductors, which offers a unique application of organic photovoltaics (OPVs): semitransparent OPVs. Recently, the exciting progress of materials design has promoted the development of semitransparent OPVs. However, in the perspective of device engineering, almost all reported works reduce the thickness of back/reflected electrode to obtain high average visible transmittance (AVT), which is a trade-off between power conversion efficiency (PCE) and the transmittance of the whole solar spectrum (visible and infrared), and therefore limit the further development.

Enabling High-Performance Tandem Organic Photovoltaic Cells by Balancing the Front and Rear Subcells.

In tandem organic photovoltaics, the front subcell is based on large-bandgap materials, whereas the case of the rear subcell is more complicated. The rear subcell is generally composed of a narrow-bandgap acceptor for infrared absorption but a large-bandgap donor to realize a high open-circuit voltage. Unfortunately, most of the ultraviolet-visible part of the photons are absorbed by the front subcell; as a result, in the rear subcell, the number of excitons generated on large-bandgap donors will be reduced significantly.

Synthesis of IrO decorated core-shell PS@PPyNH microspheres for bio-interface application.

In this paper, an effective approach is demonstrated for the fabrication of IrO-decorated polystyrene@functionalized polypyrrole (core@shell; PS@PPyNH) microspheres. The synthesis begins with the preparation of monodispersive PS microspheres with a diameter of 490 nm, by a process of emulsifier-free emulsion polymerization, followed by a copolymerization process involving pyrrole and PyNH monomers in a PS microsphere aqueous suspension, to produce uniform PS@PPyNH microspheres with a diameter of 536 nm. The loading of 2 nm IrO nanoparticles onto the PS@PPyNH microspheres can be easily adjusted by tuning the pH value of the IrO colloidal solution and the PS@PPyNH suspension.

Transparent Flexible Heteroepitaxy of NiO Coated AZO Nanorods Arrays on Muscovites for Enhanced Energy Storage Application.

Transparent flexible energy storage devices are considered as important chains in the next-generation, which are able to store and supply energy for electronic devices. Here, aluminum-doped zinc oxide (AZO) nanorods (NRs) and nickel oxide (NiO)-coated AZO NRs on muscovites are fabricated by a radio frequency (RF) magnetron sputtering deposition method. Interestingly, AZO NRs and AZO/NiO NRs are excellent electrodes for energy storage application with high optical transparency, high conductivity, large surface area, stability under compressive and tensile strain down to a bending radius of 5 mm with 1000 bending cycles.

Plasma-Induced Exfoliation Provides Onion-Like Graphene-Surrounded MoS Nanosheets for a Highly Efficient Hydrogen Evolution Reaction.

With the goal of obtaining sustainable earth-abundant electrocatalyst materials displaying high performance in the hydrogen evolution reaction (HER), here we propose a facile one-pot plasma-induced electrochemical process for the fabrication of new core-shell structures of ultrathin MoS nanosheets engulfed within onion-like graphene nanosheets (OGNs@MoS). The resultant OGNs@MoS structures not only increased the number of active sites of the semiconducting MoS nanosheets but also enhanced their conductivity. Our OGNs@MoS composites exhibited high HER performance, characterized by a low overpotential of 118 mV at a current density of 10 mA cm, a Tafel slope of 73 mV dec, and long-time stability of 10 s without degradation; this performance is much better than that of the sheet-like graphene-wrapped MoS composite GNs@MoS (182 mV, 82 mV dec) and is among the best ever reported for composites involving MoS and graphene nanosheets prepared through a simple one-batch process and using a low temperature and a short time for the HER.

Potassium-Presenting Zinc Oxide Surfaces Induce Vertical Phase Separation in Fullerene-Free Organic Photovoltaics.

Bulk heterojunction (BHJ) structure based organic photovoltaics (OPVs) have recently showed great potential for achieving high power conversion efficiencies (PCEs). An ideal BHJ structure would feature large donor/acceptor interfacial areas for efficient exciton dissociation and gradient distributions with high donor and acceptor concentrations near the anode and cathode, respectively, for efficient charge extraction. However, the random mixing of donors and acceptors in the BHJ often suffers the severe charge recombination in the interface, resulting in poor charge extraction.

Role of precursors mixing sequence on the properties of CoMnO cathode materials and their application in pseudocapacitor.

In this study, the effect of oxygen vacancy in the CoMnO on pseudocapacitive characteristics was examined, and two tetragonal CoMnO spinel compounds with different oxygen vacancy concentrations and morphologies were synthesized by controlling the mixing sequence of the Co and Mn precursors. The mixing sequence was changed; thus, morphologies were changed from spherical nanoparticles to nanoflakes and oxygen vacancies were increased. Electrochemical studies have revealed that tetragonal CoMnO spinels with a higher number of oxygen vacancies exhibit a higher specific capacitance of 1709 F g than those with a lower number of oxygen vacancies, which have a higher specific capacitance of 990 F g.

Rational Tuning of Molecular Interaction and Energy Level Alignment Enables High-Performance Organic Photovoltaics.

The performance of organic photovoltaics (OPVs) has rapidly improved over the past years. Recent work in material design has primarily focused on developing near-infrared nonfullerene acceptors with broadening absorption that pair with commercialized donor polymers; in the meanwhile, the influence of the morphology of the blend film and the energy level alignment on the efficiency of charge separation needs to be synthetically considered. Herein, the selection rule of the donor/acceptor blend is demonstrated by rationally considering the molecular interaction and energy level alignment, and highly efficient OPV devices using both-fluorinated or both-nonfluorinated donor/acceptor blends are realized.

Realizing Efficient Charge/Energy Transfer and Charge Extraction in Fullerene-Free Organic Photovoltaics via a Versatile Third Component.

Solution-processed organic photovoltaics (OPVs) based on bulk-heterojunctions have gained significant attention to alleviate the increasing demend of fossil fuel in the past two decades. OPVs combined of a wide bandgap polymer donor and a narrow bandgap nonfullerene acceptor show potential to achieve high performance. However, there are still two reasons to limit the OPVs performance.

Using Different Ions to Tune Graphene Stack Structures from Sheet- to Onion-Like During Plasma Exfoliation, with Supercapacitor Applications.

In this article, we report a facile and simple approach for tuning graphene nanosheet structures (GNS) with different ions in the electrolytes through cathodic plasma exfoliation process in electrochemical reactions. We obtained sheet- and onion-like GNS when aqueous electrolyte NaOH and HSO, respectively, were present during plasma exfoliation in the electrochemical reactions, as evidenced from scanning electron microscopy and transmission electron microscopy images. Moreover, the onion-like GNS exhibited a specific surface area of 464 m g and a supercapacitive performance of 67.

New Simultaneous Exfoliation and Doping Process for Generating MX Nanosheets for Electrocatalytic Hydrogen Evolution Reaction.

Doping nonmetal atoms into layered transition metal dichalcogenide MX structures has emerged as a promising strategy for enhancing their catalytic activities for the hydrogen evolution reaction. In this study, we developed a new and efficient one-step approach that involves simultaneous plasma-induced doping and exfoliating of MX bulk into nanosheets-such as MoSe, WSe, MoS, and WS nanosheets-within a short time and at a low temperature (ca. 80 °C).

Enhanced Photocarrier Generation with Selectable Wavelengths by M-Decorated-CuInS Nanocrystals (M = Au and Pt) Synthesized in a Single Surfactant Process on MoS Bilayers.

A facile approach for the synthesis of Au- and Pt-decorated CuInS nanocrystals (CIS NCs) as sensitizer materials on the top of MoS bilayers is demonstrated. A single surfactant (oleylamine) is used to prepare such heterostructured noble metal decorated CIS NCs from the pristine CIS. Such a feasible way to synthesize heterostructured noble metal decorated CIS NCs from the single surfactant can stimulate the development of the functionalized heterostructured NCs in large scale for practical applications such as solar cells and photodetectors.

Unraveling Sunlight by Transparent Organic Semiconductors toward Photovoltaic and Photosynthesis.

Because the visible and the infrared (IR) regions take up ∼47% and ∼51% of the energy in the solar spectrum (AM 1.5G standard), respectively, utilizing the visible light for plant growth and the IR light for power generation is potentially extremely exciting. IR-absorbing organic semiconductors, with localized IR absorption and visible-light transmittance, would be promising materials for this purpose.