Guests for Conductors Thin films of metal-organic framework (MOF) compounds are generally poor conductors because the linking organic groups usually insulators with little π-orbital conjugation. Talin et al. (p. 66 , published online 5 December) show that infiltrating copper-based MOF HKUST-1 conjugated molecule 7,7,8,8-tetracyanoquinododimethane created an air-stable material conductivities as high 7 siemens per meter.

Radial n+–p+ junction solar cells composed of densely packed pillar arrays, 25-μm-tall and 7.5 μm in diameter, fabricated from p-type silicon substrates with extremely short minority carrier diffusion lengths are investigated compared to planar cells. To understand the two times higher AM 1.5 efficiencies array cells, dark light I-V characteristics as well spectral responses presented for structures. The cell due larger short-circuit currents photon absorption thickness shorter collection...

Single molecular monolayers of oligoaniline dimers were integrated into sub-40-nm-diameter metal nanowires to form in-wire junctions. These junctions exhibited reproducible room temperature bistable switching with zero-bias high- low-current state conductance ratios up 50, threshold voltages approximately ±1.5 V, and no measurable decay in the high-state current over 22 h. Such was not observed similarly fabricated saturated dodecane (C12) or conjugated oligo(phenylene ethynylene) (OPE) The...

Polycrystalline CdS/CdTe thin-film solar cells in the superstrate configuration have been studied by spectroscopic ellipsometry (SE) using glass side illumination. In this measurement method, first reflection from ambient/glass interface is rejected, whereas second glass/film-stack collected; higher order reflections are also rejected. The SE analysis incorporates parameterized dielectric functions ε for cell component materials obtained situ and variable-angle SE. of complete cells, a...

We report a crossed-nanowire molecular junction array platform that enables direct measurement of current-voltage-temperature characteristics simultaneously with inelastic electron tunneling and Raman vibrational spectra on the same junction. Measurements dithiol-terminated oligo(phenylene-ethynylene) junctions show both spectroscopies interrogate gap-confined molecules to reveal distinct features. This versatile allows investigation advanced phenomena such as switching cooperative effects...

The binding process of quantum dots and DNA origami was monitored using a 3D, real-time, single-particle tracking system. Single-molecule events were directly observed precise measurements the diffusion coefficient second-order photon correlation function, g(2)(τ), combined to distinguish free from different conjugates nQdot-origami.

Improving the power conversion efficiency of photovoltaic (PV) devices is challenging because generation, separation and collection electron-hole pairs are strongly dependent on details nanoscale chemical composition defects which often poorly known. In this work, two novel scanning probe nano-spectroscopy techniques, direct-transmission near-field optical microscopy (dt-NSOM) photothermal induced resonance (PTIR), implemented to distribution bandgap variation in thin lamellae extracted from...

Electron beam induced current (EBIC) is a powerful characterization technique which offers the high spatial resolution needed to study polycrystalline solar cells. Current models of EBIC assume that excitations in p-n junction depletion region result perfect charge collection efficiency. However, we find CdTe and Si samples prepared by focused ion (FIB) milling, there reduced nonuniform lineshape for region. Motivated this, present model response includes effects surface recombination from...

Three-dimensionally (3D) structured photoelectrodes offer a number of potential benefits for solar fuels production compared to conventional planar photoelectrodes, including decreased optical losses, higher surface area catalysis, easier removal product species, and enhanced carrier collection efficiency. However, 3D structures can also present challenges, such as lower photovoltage larger recombination. Quantifying understanding the advantages disadvantages structuring maximize benefits,...

Solar cells made of polycrystalline thin-films can outperform their single-crystalline counterparts despite the presence grain boundaries (GBs). To unveil influence GBs, high spatial resolution characterization techniques are needed to measure local properties in vicinity. However, results obtained using single technique may provide limited aspects about GB effect. Here, we employ two techniques, near-field scanning photocurrent microscopy (NSPM) and transmission electron microscope based...

We report a fast, versatile photocurrent imaging technique to visualize the local photo response of solar energy devices and optoelectronics using near-field cathodoluminescence (CL) from homogeneous quantum dot layer. This approach is quantitatively compared with direct measurements high-resolution Electron Beam Induced Current (EBIC) thin film cell (n-CdS / p-CdTe). Qualitatively, observed image contrast similar, showing strong enhancement carrier collection efficiency at p-n junction near...

Electron beam induced current (EBIC) is a powerful technique which measures the charge collection efficiency of photovoltaics with sub-micron spatial resolution. The exciting electron results in high generation rate density electron–hole pairs, may drive system into nonlinear regimes. An analytic model presented describes EBIC response when total pair exceeds at carriers are extracted by photovoltaic cell, and accumulation screening occur. provides simple estimate onset injection regime...

Abstract We fabricate thin epitaxial crystal silicon solar cells on display glass and fused silica substrates overcoated with a seed layer. To confirm the quality of hot‐wire chemical vapor deposition epitaxy, we grow 2‐µm‐thick absorber (100) monocrystalline Si layer transfer achieve 6.5% efficiency an open circuit voltage (V OC ) 586 mV without light‐trapping features. This device enables evaluation layers glass. Using polycrystalline seeds formed from amorphous by laser‐induced mixed...

Focused ion beam (FIB) techniques have been frequently used to section metal-halide perovskites for microstructural investigations. However, the beams directly irradiating sample surface may alter its properties far different from those of pristine, potentially leading modified deterioration mechanisms under aging stressors. Here, we combine complementary approaches measure subsurface characteristics polished and identify chemical species responsible measured properties. Analysis...

Abstract Recent advances in device design and process optimizations have enabled the production of CdTe devices on flexible substrates, but necessary high‐temperature processing (>450 °C) to recrystallize grains limits use alternative lightweight substrates. Here, a new synthesis method is reported create freestanding CdS/CdTe film by combining depositions (CdS/CdTe Si/SiO 2 ) simple lift‐off water environment at room temperature. Analysis results indicate that delamination facilitated...

Micro/nano pillar arrays are a promising architecture for high-efficiency solar cells that employ inexpensive photovoltaic materials with short minority carrier diffusion lengths (L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n, p</sub> ). To investigate design tradeoffs of the radial junction array cells, we fabricated 25 μm tall c-Si devices having different diameters and filling ratios. The high-aspect-ratio n <sup...

Recent progress achieved in metal-assisted chemical etching (MACE) has enabled the production of high-quality micropillar arrays for various optoelectronic applications. Si micropillars produced by MACE often show a porous Si/SiOx shell on crystalline pillar cores introduced local electrochemical reactions. In this paper, we report distinct characteristics correlated to their compositions. Local photoluminescent (PL) images obtained with an immersion oil objective lens confocal microscopy...

Abstract Leading photovoltaic technologies such as multicrystalline Si, CdTe, Cu(In,Ga)Se 2 , and lead halide perovskites are polycrystalline, yet achieve relatively high performance. At the moment polycrystalline stand at a juncture where further advances in device performance reliability necessitate additional characterization modeling to include nanoscale property variations. Properties implications of grain boundaries previously studied, chemistry variations along individual its not...

Recent advances in fabrication have enabled radial-junction architectures for cost-effective and high-performance optoelectronic devices. Unlike a planar PN junction, geometry maximizes the optical interaction three-dimensional (3D) structures, while effectively extracting generated carriers via conformal junction. In this paper, we report characterizations of radial junctions that consist p-type Si micropillars created by deep reactive-ion etching (DRIE) an n-type layer formed phosphorus...

We investigate local electronic properties of CdTe solar cells using electron beam to excite electron-hole pairs and evaluate spatially resolved photocurrent characteristics. Standard semiconductor processes were used fabricate Ohmic metal contacts on the surface p-type / n-type CdS device extracted from a commercial panel. An ion milling process was prepare cross-sections devices. Local injection carriers controlled by an acceleration voltage (1 kV 30 kV) in scanning microscope, results...

We report on the fabrication of large-area, vertically aligned GaN epitaxial core-shell micropillar arrays. The two-step process consists inductively coupled plasma (ICP) etching lithographically patterned GaN-on-Si substrate to produce an array micropillars followed by selective growth shells over these pillars using Hydride Vapor Phase Epitaxy (HVPE). most significant aspect study is demonstration sidewall facet control in shells, ranging from {11̄01} semi-polar {11̄00} non-polar planes,...

A model for interpreting electron beam induced current (EBIC) measurements is presented, which applies when recombination within the depletion region substantial. This motivated by cross-sectional EBIC experiments on CdS-CdTe photovoltaic cells (prepared cleaving, or focused ion milling). The experimental results clearly show that maximum efficiency of carrier collection less than 100 % and varies throughout region, contrary to assumptions most models used interpret data. We describe a...

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We report an application of a pulsed ultraviolet (UV) laser ( λ = 355 nm) in producing translucent Si solar cells. This process efficiently generates densely packed microhole array on fully fabricated P‐N junction cell just few minutes. Herein, prototype cells with nominal diameter 23 μm spacing between 60 and 300 are fabricated. High‐resolution electron‐beam microscopy reveals that the UV beam introduces amorphized silicon oxide (SiO x ) proximity to patterned microholes via localized...