Scalable CIGS Solar Cells Employing a New Device Design of Nontoxic Buffer Layer and Microgrid Electrode.

The efficiency of copper indium gallium selenide (CIGS) solar cells that use transparent conductive oxide (TCO) as the top electrode decreases significantly as the device area increases owing to the poor electrical properties of TCO. Therefore, high-efficiency, large-area CIGS solar cells require the development of a novel top electrode with high transmittance and conductivity. In this study, a microgrid/TCO hybrid electrode is designed to minimize the optical and resistive losses that may occur in the top electrode of a CIGS solar cell.

Effects of the Electrical Properties of SnO and C60 on the Carrier Transport Characteristics of p-i-n-Structured Semitransparent Perovskite Solar Cells.

Recently, metal halide perovskite-based top cells have shown significant potential for use in inexpensive and high-performance tandem solar cells. In state-of-the-art p-i-n perovskite/Si tandem devices, atomic-layer-deposited SnO has been widely used as a buffer layer in the top cells because it enables conformal, pinhole-free, and highly transparent buffer layer formation. In this work, the effects of various electrical properties of SnO and C60 layers on the carrier transport characteristics and the performance of the final devices were investigated using a numerical simulation method, which was established based on real experimental data to increase the validity of the model.

Application of Bifacial Semitransparent CuInSe Absorber to the Bottom Cell in Bifacial Semitransparent Perovskite/CuInSe Tandem Solar Cell for Albedo Environment.

Although various types of bifacial solar cells exist, few studies have been conducted on bifacial semitransparent CuInSe solar cells (BS-CISe SCs) despite the attractive potential in power generation from both sides in an albedo environment. The optimized BS-CISe SCs with 300 and 800 nm-thick absorber via a streamlined single-stage co-evaporation process exhibit a power conversion efficiency (PCE) of 6.32% and 10.

YAP governs cellular adaptation to perturbation of glutamine metabolism by regulating ATF4-mediated stress response.

Proliferating cells have metabolic dependence on glutamine to fuel anabolic pathways and to refill the mitochondrial carbon pool. The Hippo pathway is essential for coordinating cell survival and growth with nutrient availability, but no molecular connection to glutamine deprivation has been reported. Here, we identify a non-canonical role of YAP, a key effector of the Hippo pathway, in cellular adaptation to perturbation of glutamine metabolism.

Suppression of fatty acid oxidation supports pancreatic cancer growth and survival under hypoxic conditions through autophagy induction.

Hypoxia, one of the key features of solid tumors, induces autophagy, which acts as an important adaptive mechanism for tumor progression under hypoxic environment. Cellular metabolic reprogramming has been correlated with hypoxia, but the molecular connection to the induction of autophagy remains obscure. Here, we show that suppression of fatty acid oxidation (FAO) by hypoxia induces autophagy in human pancreatic ductal adenocarcinoma (PDAC) cells that is required for their growth and survival.

Atom-Scale Chemistry in Chalcopyrite-Based Photovoltaic Materials Visualized by Atom Probe Tomography.

Chalcopyrite-based materials for photovoltaic devices tend to exhibit complex structural imperfections originating from their polycrystalline nature; nevertheless, properly controlled devices are surprisingly irrelevant to them in terms of resulting device performances. The present work uses atom probe tomography to characterize co-evaporated high-quality Cu(In,Ga)Se (CIGS) films on flexible polyimide substrates either with or without doping with Na or doping with Na followed by K via a post-deposition treatment. The intent is to elucidate the unique characteristics of the grain boundaries (GBs) in CIGS, in particular the correlations/anti-correlations between matrix elements and the alkali dopants.

Tailored Band Structure of Cu(In,Ga)Se Thin-Film Heterojunction Solar Cells: Depth Profiling of Defects and the Work Function.

An efficient carrier transport is essential for enhancing the performance of thin-film solar cells, in particular Cu(In,Ga)Se (CIGS) solar cells, because of their great sensitivities to not only the interface but also the film bulk. Conventional methods to investigate the outcoming carriers and their transport properties measure the current and voltage either under illumination or dark conditions. However, the evaluation of current and voltage changes along the cross-section of the devices presents several limitations.

Mitochondrial Glutamine Metabolism Determines Senescence Induction After Chemotherapy.

Background/aim: Cellular senescence is an important tumor-suppressive mechanism that arrests the cell cycle of damaged cells after diverse stresses. This study aimed to elucidate the role of mitochondrial glutamine (Gln) metabolism in senescence cell-fate decision after DNA damage.

Materials And Methods: β-galactosidase staining was used to determine senescence induction.

Optimal CdS Buffer Thickness to Form High-Quality CdS/Cu(In,Ga)Se Junctions in Solar Cells without Plasma Damage and Shunt Paths.

CdS has been known to be one of the best junction partners for Cu(In,Ga)Se (CIGS) in CIGS solar cells. However, the use of thick CdS buffer decreases the short-circuit current density of CIGS solar cells. There are two obstacles that limit the use of ultrathin CdS.

Passivation of Deep-Level Defects by Cesium Fluoride Post-Deposition Treatment for Improved Device Performance of Cu(In,Ga)Se Solar Cells.

Heavy-alkali post-deposition treatments (PDTs) utilizing Cs or Rb has become an indispensable step in producing high-performance Cu(In,Ga)Se (CIGS) solar cells. However, full understanding of the mechanism behind the improvements of device performance by heavy-alkali treatments, particularly in terms of potential modification of defect characteristics, has not been reached yet. Here, we present an extensive study on the effects of CsF-PDT on material properties of CIGS absorbers and the performance of the final solar devices.

Fabrication of Robust Nanoscale Contact between a Silver Nanowire Electrode and CdS Buffer Layer in Cu(In,Ga)Se2 Thin-film Solar Cells.

Silver nanowire transparent electrodes have been employed as window layers for Cu(In,Ga)Se2 thin-film solar cells. Bare silver nanowire electrodes normally result in very poor cell performance. Embedding or sandwiching silver nanowires using moderately conductive transparent materials, such as indium tin oxide or zinc oxide, can improve cell performance.

Mitochondrial GPT2 plays a pivotal role in metabolic adaptation to the perturbation of mitochondrial glutamine metabolism.

Cancer cells exhibit metabolic dependence on mitochondrial glutamine metabolism that provides them with the substrates required for rapid proliferation. Despite the extensive efforts to target this glutamine addiction for therapeutic purposes, the adaptive metabolic responses and the mechanisms whereby cells maintain their unlimited growth remain areas of active investigation. Here we report that mitochondrial glutamate-pyruvate transaminase 2 (GPT2) contributes to cell survival and growth by sustaining the tricarboxylic acid (TCA) cycle anaplerosis after the inhibition of glutaminase (GLS), the first enzyme for mitochondrial glutamine metabolism.

PGC1α is required for the induction of contact inhibition by suppressing ROS.

Contact inhibition (CI) is an important tumor-suppressive mechanism that arrests cell cycle when cells reach high density. Indeed, CI is aberrantly absent in cancer cells and the dysregulation of this can contribute to tumorigenesis. Previously, it has been shown that reactive oxygen species (ROS) levels are repressed at high cell density, which is required for CI, but no molecular mechanism of this ROS regulation has been reported.

Carbon-Impurity Affected Depth Elemental Distribution in Solution-Processed Inorganic Thin Films for Solar Cell Application.

A common feature of the inorganic thin films including Cu(In,Ga)(S,Se)2 fabricated by nonvacuum solution-based approaches is the doubled-layered structure, with a top dense inorganic film and a bottom carbon-containing residual layer. Although the latter has been considered to be the main efficiency limiting factor, (as a source of high series resistance), the exact influence of this layer is still not clear, and contradictory views are present. In this study, using a CISe as a model system, we report experimental evidence indicating that the carbon residual layer itself is electrically benign to the device performance.

Carbon- and oxygen-free Cu(InGa)(SSe)₂ solar cell with a 4.63% conversion efficiency by electrostatic spray deposition.

We have demonstrated the first example of carbon- and oxygen-free Cu(In,Ga)(SSe)2 (CIGSSe) absorber layers prepared by electrospraying a CuInGa (CIG) precursor followed by annealing, sulfurization, and selenization at elevated temperature. X-ray diffraction and scanning electron microscopy showed that the amorphous as-deposited (CIG) precursor film was converted into polycrystalline CIGSSe with a flat-grained morphology after post-treatment. The optimal post-treatment temperature was 300 °C for annealing and 500 °C for both sulfurization and selenization, with a ramp rate of 5 °C/min.

Amorphous Cu-In-S nanoparticles as precursors for CuInSe2 thin-film solar cells with a high efficiency.

CuInSe2 (CISe) absorber layers for thin-film solar cells were fabricated through the selenization of amorphous Cu-In-S nanoparticles, which were prepared by using a low-temperature colloidal process within one minute without any external heating. Two strategies for obtaining highly dense CISe absorber films were used in this work; the first was the modification of nanoparticle surface through chelate complexation with ethanolamine, and the second strategy utilized the lattice expansion that occurred when S atoms in the precursor particles were replaced with Se during selenization. The synergy of these two strategies allowed formation of highly dense CISe thin films, and devices fabricated using the absorber layer demonstrated efficiencies of up to 7.

CuInSe₂ thin-film solar cells with 7.72 % efficiency prepared via direct coating of a metal salts/alcohol-based precursor solution.

A simple direct solution coating process for forming CuInSe₂ (CIS) thin films was described, employing a low-cost and environmentally friendly precursor solution. The precursor solution was prepared by mixing metal acetates, ethanol, and ethanolamine. The facile formation of a precursor solution without the need to prefabricate nanoparticles enables a rapid and easy processing, and the high stability of the solution in air further ensures the precursor preparation and the film deposition in ambient conditions without a glove box.

Microfabrication and optical properties of highly ordered silver nanostructures.

Using thermal evaporation, we fabricated five uniform and regular arrays of Ag nanostructures with different shapes that were based on an anodized aluminum oxide template and analyzed their optical properties. Round-top-shaped structures are obtained readily, whereas to obtain needle-on-round-top-shaped and needle-shaped structures, control of the directionality of evaporation, pore size, length, temperature of the substrate, etc., was required.

CuInSe2 (CIS) thin films prepared from amorphous Cu-In-Se nanoparticle precursors for solar cell application.

CuInSe(2) (CIS) absorber layers for thin film solar cells were formed via a nonvacuum route using nanoparticle precursors. A low-temperature colloidal process was used to prepare nanoparticles by which amorphous Cu-In-Se nanoparticles were formed within 1 min of reaction without any external heating. Raman spectra of the particles revealed that they were presumably mixtures of amorphous Cu-Se and In-Se binaries.

Biomolecular embossing.

The replica molding and embossing of DNA texture has been achieved using a conventional polyurethane mold. The final process requires no additional or separate extraction phases. The polyurethane replica is stable up to 150 degrees C and possesses a good longevity and a capacity to emboss a biological entity into a thermosetting plastic such as poly(ethylene terephthalate).