Single stranded 1D-helical Cu coordination polymer for ultra-sensitive ammonia sensing at room temperature.

With the increasing demand for ammonia applications, there is a significant focus on improving NH detection performance at room temperature. In this study, we introduce a groundbreaking NH gas sensor based on Cu(I)-based coordination polymers, featuring semiconducting, single stranded 1D-helical nanowires constructed from Cu-Cl and -methylthiourea (MTCP). The MTCP demonstrates an exceptional response to NH gas (>900% at 100 ppm) and superior selectivity at room temperature compared to current materials.

Ultrathin, High-Aspect-Ratio Bismuth Sulfohalide Nanowire Bundles for Solution-Processed Flexible Photodetectors.

In this study, a novel synthesis of ultrathin, highly uniform colloidal bismuth sulfohalide (BiSX where X = Cl, Br, I) nanowires (NWs) and NW bundles (NBs) for room-temperature and solution-processed flexible photodetectors are presented. High-aspect-ratio bismuth sulfobromide (BiSBr) NWs are synthesized via a heat-up method using bismuth bromide and elemental S as precursors and 1-dodecanethiol as a solvent. Bundling of the BiSBr NWs occurs upon the addition of 1-octadecene as a co-solvent.

Synthesis and Characteristics of Mesoporous Copper Cobalt Oxides Using the Inverse Micelle Method Fabricated for Supercapacitors.

Mesoporous materials have gained considerable attention in the fabrication of supercapacitor electrodes because of their large surface areas and controlled porosities. This study reports the synthesis of mesoporous CuCoO powders using the inverse micelle method. X-ray diffraction, N sorption measurement, transmission electron microscopy, and X-ray photoelectron spectroscopy were performed to investigate the properties of the powders.

Photonic control of ligand nanospacing in self-assembly regulates stem cell fate.

Extracellular matrix (ECM) undergoes dynamic inflation that dynamically changes ligand nanospacing but has not been explored. Here we utilize ECM-mimicking photocontrolled supramolecular ligand-tunable Azo self-assembly composed of azobenzene derivatives (Azo) stacked via cation-π interactions and stabilized with RGD ligand-bearing poly(acrylic acid). Near-infrared-upconverted-ultraviolet light induces -Azo-mediated inflation that suppresses cation-π interactions, thereby inflating liganded self-assembly.

An ultra-sensitive colloidal quantum dot infrared photodiode exceeding 100 000% external quantum efficiency photomultiplication.

In this study, we present ultrasensitive infrared photodiodes based on PbS colloidal quantum dots (CQDs) using a double photomultiplication strategy that utilizes the accumulation of both electron and hole carriers. While electron accumulation was induced by ZnO trap states that were created by treatment in a humid atmosphere, hole accumulation was achieved using a long-chain ligand that increased the barrier to hole collection. Interestingly, we obtained the highest responsivity in photo-multiplicative devices with the long ligands, which contradicts the conventional belief that shorter ligands are more effective for optoelectronic devices.

Smart building block with colored radiative cooling devices and quantum dot light emitting diodes.

In this study, we design a smart building block with quantum-dot light-emitting diode (QLED) and colored radiative cooling devices. A smart light-emitting building block is fabricated using a bottom-inverted QLED that emits green light, an insulating layer, and a top radiative cooling structure that emits mid-infrared light. The heat generated during QLED operation is measured and analyzed to investigate the correlation between heat and QLED degradation.

Vivid Colored Cooling Structure Managing Full Solar Spectrum via Near-Infrared Reflection and Photoluminescence.

Colored radiative cooling (CRC) offers an attractive alternative for surface and space cooling, while preserving the aesthetics of an object. However, there has been no study on the CRC using phosphors in regard to vivid coloration, sophisticated performance investigation, retention of properties, functionality, and structural flexibility all at once. Thus, to manage the entire solar spectrum, a colored cooling structure comprising a near-infrared (NIR)-reflective bottom layer and a top colored layer with a phosphor-embedded polymer matrix is proposed.

Ultra-Low Noise Level Infrared Quantum Dot Photodiodes with Self-Screenable Polymeric Optical Window.

Quantum dot photodiodes (QPDs) have garnered significant attention because of their unparalleled near-infrared (NIR) detection capabilities, primarily attributable to their size-dependent bandgap tunability. Nevertheless, the broadband absorption spectrum of QPD engenders substantial noise floor within superfluous visible light regions, notably hindering their use in several emerging applications necessitating the detection of faint micro-light signals. To overcome these hurdles, a self-screenable NIR QPD featuring an internal optical filter with a thick polymeric interlayer to reduce electronic noise is demonstrated.

Understanding Colloidal Quantum Dot Device Characteristics with a Physical Model.

Colloidal quantum dots (CQDs) are finding increasing applications in optoelectronic devices, such as photodetectors and solar cells, because of their high material quality, unique and attractive properties, and process flexibility without the constraints of lattice match and thermal budget. However, there is no adequate device model for colloidal quantum dot heterojunctions, and the popular Shockley-Quiesser diode model does not capture the underlying physics of CQD junctions. Here, we develop a compact, easy-to-use model for CQD devices rooted in physics.

Design Rule of Electron- and Hole-Selective Contacts for Polycrystalline Silicon-Based Passivating Contact Solar Cells.

A crystalline silicon (c-Si) solar cell with a polycrystalline silicon/SiO (poly-Si/SiO) structure, incorporating both electron and hole contacts, is an attractive choice for achieving ideal carrier selectivity and serving as a fundamental component in high-efficiency perovskite/Si tandem and interdigitated back-contact solar cells. However, our understanding of the carrier transport mechanism of hole contacts remains limited owing to insufficient studies dedicated to its investigation. There is also a lack of comparative studies on the poly-Si/SiO electron and hole contacts for ideal carrier-selective solar cells.

Ultrasensitive Near-Infrared InAs Colloidal Quantum Dot-ZnON Hybrid Phototransistor Based on a Gradated Band Structure.

Amorphous metal oxide semiconductor phototransistors (MOTPs) integrated with colloidal quantum dots (QDs) (QD-MOTPs) are promising infrared photodetectors owing to their high photoconductive gain, low off-current level, and high compatibility with pixel circuits. However, to date, the poor mobility of conventional MOTPs, such as indium gallium zinc oxide (IGZO), and the toxicity of lead (Pb)-based QDs, such as lead sulfide and lead selenide, has limited the commercial applications of QD-MOTPs. Herein, an ultrasensitive QD-MOTP fabricated by integrating a high-mobility zinc oxynitride (ZnON)-based MOTP and lead-free indium arsenide (InAs) QDs is demonstrated.

Charge transport transition of PEDOT:PSS thin films for temperature-insensitive wearable strain sensors.

In this study, a temperature-insensitive strain sensor that detects only the strain without responding to the temperature was designed. The transport mechanism and associated temperature coefficient of resistance (TCR) of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin film were modified through secondary doping with dimethyl sulfoxide (DMSO). Upon DMSO-doping, the carrier transport mechanism of the PEDOT:PSS thin film transitioned from hopping to band-like transport, with a morphological change.

Contact Enhancement in Nanoparticle Assemblies through Electrophoretic Deposition.

A strong interparticle connection needs to be realized to harvest unique nanoscale features of colloidal nanoparticles (NPs) in film structures. Constructing a strong contact and adhesion of NPs on a substrate is an essential process for improved NP film properties, and therefore, its key factors should be determined by understanding the NP deposition mechanism. Herein, we investigated the critical factors leading to the robust and strong adherence of the film structure and revealed that the NP deposition mechanism involved the role of surfactant ligands during electrophoretic deposition (EPD).

Contribution of Sub-Gap States to Broadband Infrared Response in Organic Bulk Heterojunctions.

This work studied a series of infrared detectors comprised of organic bulk heterojunctions to explain the origin of their broadband spectral response from the visible to the infrared spanning 1 to 8 μm and the transition from photonic to bolometric operation. Through comparisons of the detector current and the sub-bandgap density of states, the mid- and long-wave infrared response was attributed to charge trap-and-release processes that impact thermal charge generation and the activation energy of charge mobility. We further demonstrate how the sub-bandgap characteristics, mobility activation energy, and effective bandgap are key design parameters for controlling the device temperature coefficient of resistance, which reached up to -7%/K, better than other thin-film materials such as amorphous silicon and vanadium oxide.

Acid-Base Reaction-Assisted Quantum Dot Patterning via Ligand Engineering and Photolithography.

The integration of quantum dots (QDs) into device arrays for high-resolution display and imaging sensor systems remains a significant challenge in research and industry because of issues associated with the QD patterning process. It is difficult for conventional patterning processes such as stamping, inkjet printing, and photolithography to employ QDs and fabricate high-resolution patterns without degrading the properties of QDs. Here, we introduce a novel strategy for the QD patterning process by treating QDs with a bifunctional ligand for acid-base reaction-assisted photolithography.

Surface-Dominated HfO Nanorod-Based Memristor Exhibiting Highly Linear and Symmetrical Conductance Modulation for High-Precision Neuromorphic Computing.

The switching characteristics and performance of oxide-based memristors are predominately determined by oxygen- or oxygen-vacancy-mediated redox reactions and the consequent formation of conducting filaments (CFs). Devices using oxide thin films as the switching layer usually require an electroforming process for subsequent switching operations, which induces large device-to-device variations. In addition, the hard-to-control redox reaction during repeated switching causes random fluctuations or degradation of each resistance state, hindering reliable switching operations.

Designing a self-classifying smart device with sensor, display, and radiative cooling functions spectrum-selective response.

This paper presents a self-classifying smart device that intelligently differentiates and operates three functions: electroluminescence display, ultraviolet light sensor, and thermal management radiative cooling. The optical and electrical properties of the materials and structures are designed to achieve a spectrum-selective response, which enables the integration of the aforementioned functions into one device without any noise or interference. Spectrum-selective materials that absorb, emit, and radiate light with ultraviolet to mid-infrared wavelengths and device structures designed to prevent interference are achieved by using thin metal films, dielectric layers, and nanocrystals.