Hierarchical Transparent Back Contacts for Bifacial CdTe PV.

A hierarchical transparent back contact leveraging an AlGaO passivating layer, TiCT MXene with a high work function, and a transparent cracked film lithography (CFL) templated nanogrid is demonstrated on copper-free cadmium telluride (CdTe) devices. AlGaO improves device open-circuit voltage but reduces the fill factor when using a CFL-templated metal contact. Including a TiCT interlayer improves the fill factor, lowers detrimental Schottky barriers, and enables metallization with CFL by providing transverse conduction into the nanogrid.

LED-based characterization of solar cells for underwater applications.

Improved solar energy harvesting in aquatic environments would allow for superior environmental monitoring. However, developing underwater solar cells is challenging as evaluation typically requires deployment in the field or in large water tanks that can simulate aquatic light conditions. Here, we present a protocol to test underwater solar cells using a light-emitting diode (LED)-based characterization technique usable in a typical laboratory setting.

Towards High-Efficiency Photon Trapping in Thin-Film Perovskite Solar Cells Using Etched Fractal Metadevices.

Reflective loss is one of the main factors contributing to power conversion efficiency limitation in thin-film perovskite solar cells. This issue has been tackled through several approaches, such as anti-reflective coatings, surface texturing, or superficial light-trapping metastructures. We report detailed simulation-based investigations on the photon trapping capabilities of a standard Methylammonium Lead Iodide (MAPbI3) solar cell, with its top layer conveniently designed as a fractal metadevice, to reach a reflection value R<0.

Narrowing the Phase Distribution of Quasi-2D Perovskites for Stable Deep-Blue Electroluminescence.

Solution-processed quasi-2D perovskites contain multiple quantum wells with a broad width distribution. Inhomogeneity results in the charge funneling into the smallest bandgap components, which hinders deep-blue emission and accelerates Auger recombination. Here, a synthetic strategy applied to a range of quasi-2D perovskite systems is reported, that significantly narrows the quantum well dispersity.

Identifying optimal photovoltaic technologies for underwater applications.

Improving solar energy collection in aquatic environments would allow for superior environmental monitoring and remote sensing, but the identification of optimal photovoltaic technologies for such applications is challenging as evaluation requires either field deployment or access to large water tanks. Here, we present a simple bench-top characterization technique that does not require direct access to water and therefore circumvents the need for field testing during initial trials of development. Employing LEDs to simulate underwater solar spectra at various depths, we compare Si and CdTe solar cells, two commercially available technologies, with GaInP cells, a technology with a wide bandgap close to ideal for underwater solar harvesting.

Localizing Tungsten Single Atoms around Tungsten Nitride Nanoparticles for Efficient Oxygen Reduction Electrocatalysis in Metal-Air Batteries.

Combining isolated atomic active sites with those in nanoparticles for synergizing complex multistep catalysis is being actively pursued in the design of new electrocatalyst systems. However, these novel systems have been rarely studied due to the challenges with synthesis and analysis. Herein, a synergistically catalytic performance is demonstrated with a 0.

In Operando Visualization and Dynamic Manipulation of Electrochemical Processes at the Electrode-Solution Interface.

Revealing the dynamic processes at the electrode-solution interface is imperative for understanding electrochemical phenomena. Most techniques have been developed to sense the electrode surface changes at the nanoscale, but provide limited information on potential-induced interfacial ion redistribution at the mesoscale. Herein, we present an in operando visualization method utilizing a microfabricated electrochemical cell combined with a laser scanning confocal microscope to observe high-resolution and fast-response interfacial processes.

CO doping of organic interlayers for perovskite solar cells.

In perovskite solar cells, doped organic semiconductors are often used as charge-extraction interlayers situated between the photoactive layer and the electrodes. The π-conjugated small molecule 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9-spirobifluorene (spiro-OMeTAD) is the most frequently used semiconductor in the hole-conducting layer, and its electrical properties considerably affect the charge collection efficiencies of the solar cell. To enhance the electrical conductivity of spiro-OMeTAD, lithium bis(trifluoromethane)sulfonimide (LiTFSI) is typically used in a doping process, which is conventionally initiated by exposing spiro-OMeTAD:LiTFSI blend films to air and light for several hours.

Weak polyelectrolyte-based multilayers via layer-by-layer assembly: Approaches, properties, and applications.

Layer-by-layer (LbL) assembly is a nanoscale technique with great versatility, simplicity and molecular-level processing of various nanoscopic materials. Weak polyelectrolytes have been used as major building blocks for LbL assembly providing a fundamental and versatile tool to study the underlying mechanisms and practical applications of LbL assembly due to its pH-responsive charge density and molecular conformation. Because of high-density uncompensated charges and high-chain mobility, weak polyelectrolyte exponential multilayer growth is considered one of the fastest developing areas for organized molecular films.

Electrochemical-Osmotic Process for Simultaneous Recovery of Electric Energy, Water, and Metals from Wastewater.

A highly-efficient, autonomous electrochemical-osmotic system (EOS) is developed for simultaneous recovery of electric energy, water, and metals from wastewater. We demonstrate that the system can generate a maximum electric power density of 10.5 W m using a spontaneous Fe/Cu galvanic cell, while simultaneously achieving copper recovery from wastewater.

High-throughput, combinatorial synthesis of multimetallic nanoclusters.

Multimetallic nanoclusters (MMNCs) offer unique and tailorable surface chemistries that hold great potential for numerous catalytic applications. The efficient exploration of this vast chemical space necessitates an accelerated discovery pipeline that supersedes traditional "trial-and-error" experimentation while guaranteeing uniform microstructures despite compositional complexity. Herein, we report the high-throughput synthesis of an extensive series of ultrafine and homogeneous alloy MMNCs, achieved by 1) a flexible compositional design by formulation in the precursor solution phase and 2) the ultrafast synthesis of alloy MMNCs using thermal shock heating (i.

Mechanically strong and electrically conductive multilayer MXene nanocomposites.

Polymer nanocomposites offer the opportunity to bridge properties of nanomaterials to the macroscale. In this work, layer-by-layer (LbL) assembly is used to demonstrate nanocomposites of 2D titanium carbide nanosheets (MXene) and clay nanoplatelets (montmorillonite) to fabricate freestanding thin films with unique multifunctional properties. These thin films can be tuned by adjusting the thickness to exhibit a tensile strength of 138 MPa-225 MPa, EMI specific shielding effectiveness normalized to thickness and density up to 24 550 dB cm g, and sheet resistance from 855 Ω sq-3.

A Promising Carbon/g-C N Composite Negative Electrode for a Long-Life Sodium-Ion Battery.

2D graphitic carbon nitride (g-C N ) nanosheets are a promising negative electrode candidate for sodium-ion batteries (NIBs) owing to its easy scalability, low cost, chemical stability, and potentially high rate capability. However, intrinsic g-C N exhibits poor electronic conductivity, low reversible Na-storage capacity, and insufficient cyclability. DFT calculations suggest that this could be due to a large Na ion diffusion barrier in the innate g-C N nanosheet.

Recent Advances in Metallic Glass Nanostructures: Synthesis Strategies and Electrocatalytic Applications.

Recent advances in metallic glass nanostructures (MGNs) are reported, covering a wide array of synthesis strategies, computational discovery, and design solutions that provide insight into distinct electrocatalytic applications. A brief introduction to the development and unique features of MGNs with an overview of top-down and bottom-up synthesis strategies is presented. Specifically, the morphology and structural analysis of several examples applying MGNs as electrodes are highlighted.

PEOz-PEDOT:PSS Composite Layer: A Route to Suppressed Hysteresis and Enhanced Open-Circuit Voltage in a Planar Perovskite Solar Cell.

The successful commercialization of perovskite solar cells (Pvs-SCs) calls for the need to find low-temperature processable interlayers with outstanding charge-transport features. In this work, we strategically blend poly(2-ethyl-2-oxazoline) (PEOz) with PEDOT:PSS as the modified hole transport layer (HTL) to achieve high-efficiency P-I-N CHNHPbI Pvs-SCs. The PEOz-PEDOT:PSS HTL exhibits enhanced features over the conventional layer including the following: (1) promoting perovskite with enlarged grain sizes to decrease the perovskite layer's recombination, (2) increasing the work function of the HTL, and (3) decreasing the noncapacitive current in Pvs-SCs.

Spray coating of the PCBM electron transport layer significantly improves the efficiency of p-i-n planar perovskite solar cells.

The p-i-n structure for perovskite solar cells has recently shown significant advantages in minimal hysteresis effects, and scalable manufacturing potential using low-temperature solution processing. However, the power conversion efficiency (PCE) of the perovskite p-i-n structure remains low mainly due to limitations using a flat electron transport layer (ETL). In this work, we demonstrate a new approach using spray coating to fabricate the [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) ETL.

Three-Phase Morphology Evolution in Sequentially Solution-Processed Polymer Photodetector: Toward Low Dark Current and High Photodetectivity.

Sequentially solution-processed polymer photodetectors (SSP PPDs) based on poly(3-hexylthiophene-2,5-diyl) (P3HT)/[6,6]-phenyl C-butyric acid methyl ester (PCBM) are fabricated by depositing the top layers of PCBM from an appropriate cosolvent of 2-chlorophenol (2-CP)/o-dichlorobenzene (ODCB) onto the predeposited bottom layers of P3HT. By adjusting the ratio of 2-CP/ODCB in the top PCBM layers, the resulting SSP PPD shows a decreased dark current and an increased photocurrent, leading to a maximum detectivity of 1.23 × 10 Jones at a wavelength of 550 nm.

Charge Transfer from Carbon Nanotubes to Silicon in Flexible Carbon Nanotube/Silicon Solar Cells.

Mechanical fragility and insufficient light absorption are two major challenges for thin flexible crystalline Si-based solar cells. Flexible hybrid single-walled carbon nanotube (SWNT)/Si solar cells are demonstrated by applying scalable room-temperature processes for the fabrication of solar-cell components (e.g.

Nanopatterned Bulk Metallic Glass Biosensors.

Nanopatterning as a surface area enhancement method has the potential to increase signal and sensitivity of biosensors. Platinum-based bulk metallic glass (Pt-BMG) is a biocompatible material with electrical properties conducive for biosensor electrode applications, which can be processed in air at comparably low temperatures to produce nonrandom topography at the nanoscale. Work presented here employs nanopatterned Pt-BMG electrodes functionalized with glucose oxidase enzyme to explore the impact of nonrandom and highly reproducible nanoscale surface area enhancement on glucose biosensor performance.

Exploring a wider range of Mg-Ca-Zn metallic glass as biocompatible alloys using combinatorial sputtering.

In order to bypass the limitation of bulk metallic glasses fabrication, we synthesized thin film metallic glasses to study the corrosion characteristics of a wide atomic% composition range, Mg(35.9-63%)Ca(4.1-21%)Zn(17.

Perovskite solar cells with a DMSO-treated PEDOT:PSS hole transport layer exhibit higher photovoltaic performance and enhanced durability.

Despite being the most commonly used hole transport layer for p-i-n perovskite solar cells, the conventional PEDOT:PSS layer is far from being optimal for the best photovoltaic performance. Herein, we demonstrate highly conductive thin DMSO-doped PEDOT:PSS layers which significantly enhance the light harvesting, charge extraction, and photocurrent production of organo-lead iodide devices. Both imaging and X-ray analysis reveal that the perovskite thin films grown on DMSO-doped PEDOT:PSS exhibit larger grains with increased crystallinity.

Heme biomolecule as redox mediator and oxygen shuttle for efficient charging of lithium-oxygen batteries.

One of the greatest challenges with lithium-oxygen batteries involves identifying catalysts that facilitate the growth and evolution of cathode species on an oxygen electrode. Heterogeneous solid catalysts cannot adequately address the problematic overpotentials when the surfaces become passivated. However, there exists a class of biomolecules which have been designed by nature to guide complex solution-based oxygen chemistries.

Solution-processed titanium carbide MXene films examined as highly transparent conductors.

MXenes, a new family of two-dimensional structures, have recently gained significant attention due to their unique physical properties suitable for a wide range of potential applications. Here we introduce TiCT delaminated monolayers as ultrathin transparent conductors with properties exceeding comparable reduced graphene oxide films. Solution processed TiCT films exhibit sheet resistances as low as 437 Ω sq with 77% transmittance at 550 nm.

A New Design Strategy for Observing Lithium Oxide Growth-Evolution Interactions Using Geometric Catalyst Positioning.

Understanding the catalyzed formation and evolution of lithium-oxide products in Li-O2 batteries is central to the development of next-generation energy storage technology. Catalytic sites, while effective in lowering reaction barriers, often become deactivated when placed on the surface of an oxygen electrode due to passivation by solid products. Here we investigate a mechanism for alleviating catalyst deactivation by dispersing Pd catalytic sites away from the oxygen electrode surface in a well-structured anodic aluminum oxide (AAO) porous membrane interlayer.