Printed Organic One‐Time Programmable ROM Array Using Anti‐fuse Capacitor

This paper proposes printed organic one‐time programmable read‐only memory (PROM). The organic PROM cell consists of a capacitor and an organic p‐type metal‐oxide semiconductor (PMOS) transistor. Initially, all organic PROM cells with unbroken capacitors store “0.” Some organic PROM cells are programmed to “1” by electrically breaking each capacitor with a high voltage. After the capacitor breaking, the current flowing through the PROM cell significantly increases. The memory data is read out by sensing the current in the PROM cell. 16‐bit organic PROM cell arrays are fabricated with the printed organic PMOS transistor and capacitor process. The organic PROM cells are programmed with –50 V, and they are read out with –20 V. The area of the 16‐bit organic PROM array is 70.6 mm².     

Concurrent Modulation of Competitive Mechanisms to Design Stimuli‐Responsive Ln‐MOFs: A Light‐Operated Dual‐Mode Assay for Oxidative DNA Damage

The identification of biomolecules for disease diagnosis requires facile analytical technologies with high precision and reliability. Several signal transduction pathways have inspired the development of various bioanalytical systems. However, most systems are greatly limited by a single‐mechanism/mode assay, which easily results in false‐positive/negative results. Herein, a multiple‐mechanism‐driven optical biosensor for 8‐oxo‐2′‐deoxyguanosine (8‐oxo‐dG), an early pathological signature of DNA lesions and various diseases, is designed by assembling adenine as a recognition element, mellitic acid as energy donors and Eu³⁺ as signal reporters into one metal‐organic framework (MOF) system. Significantly, by regulating the delicate competition between the different mechanisms, the fabricated single platform (Eu‐ade‐MOF) concurrently provides two switchable approaches for rapid qualitative (30 s and 4 min) and quantitive (ppb level) recognition of 8‐oxo‐dG in both complex artificial and real human urine environments. Compared with those single‐mechanism/mode‐driven detections, this light‐operated dual‐mode analysis system can inherently boost the analysis reliability and largely minimize the chances of false negatives/positives for a non‐invasive diagnosis of DNA damage and related diseases. This work represents the first effort in designing a luminescent sensor coupling multiple mechanisms in a single interface to determine DNA damage degree and provides a new approach for developing multimode analysis platforms for human health monitoring.     

Single‐Crystal‐to‐Single‐Crystal Transformation of a Europium(III) Metal–Organic Framework Producing a Multi‐responsive Luminescent Sensor

A sensor with a red‐emission signal is successfully obtained by the solvothermal reaction of Eu³⁺ and heterofunctional ligand bpydbH₂ (4,4′‐(4,4′‐bipyridine‐2,6‐diyl) dibenzoic acid), followed by terminal‐ligand exchange in a single‐crystal‐to‐single‐crystal transformation. As a result of treatments both before and after the metal–organic framework formation, accessible Lewis‐base sites and coordinated water molecules are successfully anchored onto the host material, and they act as signal transmission media for the recognition of analytes at the molecular level. This is the first reported sensor based on a metal–organic framework (MOF) with multi‐responsive optical sensing properties. It is capable of sensing small organic molecules and inorganic ions, and unprecedentedly it can discriminate among the homologues and isomers of aliphatic alcohols as well as detect highly explosive 2,4,6‐trinitrophenol (TNP) in water or in the vapor phase. This work highlights the practical application of luminescent MOFs as sensors, and it paves the way toward other multi‐responsive sensors by demonstrating the incorporation of various functional groups into a single framework.     

Rapid Detection of the Biomarkers for Carcinoid Tumors by a Water Stable Luminescent Lanthanide Metal–Organic Framework Sensor

Serotonin (5‐hydroxytryptamine, HT), a neurotransmitter, and its main metabolite 5‐hydroxyindole‐3‐acetic acid (HIAA) are biomarkers for carcinoid tumors. They can be quantitatively detected by a new luminescent sensor based on a water stable lanthanide metal–organic framework (Ln‐MOF). This Ln‐MOF features a (3,4)‐connected topology containing 1D channels occupied by lattice water molecules. Luminescent studies reveal that high luminescence quenching efficiency occurs upon the addition of HT and HIAA. The Ln‐MOF also displays excellent sensitivity with fast response within 1 min, good reusability, and detection limits as low as 0.66 and 0.54 × 10^?6m for HT and HIAA, respectively. In addition, the sensing function exhibits excellent selectivity even in the presence of other neurotransmitters and the main coexisting species in blood plasma and urine.     

Plasmon‐Induced Sub‐Bandgap Photodetection with Organic Schottky Diodes

Organic materials for near‐infrared (NIR) photodetection are in the focus for developing organic optical‐sensing devices. The choice of materials for bulk‐type organic photodetectors is limited due to effects like high nonradiative recombination rates for low‐gap materials. Here, an organic Schottky barrier photodetector with an integrated plasmonic nanohole electrode is proposed, enabling structure‐dependent, sub‐bandgap photodetection in the NIR. Photons are detected via internal photoemission (IPE) process over a metal/organic semiconductor Schottky barrier. The efficiency of IPE is improved by exciting localized surface plasmon resonances, which are further enhanced by coupling to an out‐of‐plane Fabry–Pérot cavity within the metal/organic/metal device configuration. The device allows large on/off ratio (>1000) and the selective control of individual pixels by modulating the Schottky barrier height. The concept opens up new design and application possibilities for organic NIR photodetectors.     

Flexible Near‐Infrared Plastic Phototransistors with Conjugated Polymer Gate‐Sensing Layers

Flexible near‐infrared (NIR) light‐sensing detectors are strongly required in the fast‐growing flexible electronics era, because they can serve as a vision system like eyes in various innovative applications including humanoid robots. Recently, keen interest has been paid to organic phototransistors due to their unique signal amplification and active matrix driving features over organic photodiodes. However, conventional NIR‐sensing organic phototransistors suffer from the limited use of organic materials because the channel layers play a dual role in both charge transport and sensing so that organic semiconducting materials with reasonably high charge mobility can be applied only. Here, it is demonstrated that a conjugated polymer, poly[{2,5‐bis‐(2‐ethylhexyl)‐3,6‐bis‐(thien‐2‐yl)‐pyrrolo[3,4‐c]pyrrole‐1,4‐diyl}‐co‐{2,2′‐(2,1,3‐benzothiadiazole)]‐5,5′‐diyl}] (PEHTPPD‐BT), which exhibits no transistor performance as a channel layer, can stably detect a NIR light (up to 1000 nm) as a gate‐sensing layer (GSL) when it is placed between gate‐insulating layers and gate electrodes. The flexible array (10 × 10) detectors with the PEHTPPD‐BT GSLs could effectively sense NIR light without visible light interference by applying visible light cut films.     

Durable Ultraflexible Organic Photovoltaics with Novel Metal‐Oxide‐Free Cathode

Flexible and stretchable organic photovoltaics (OPVs) are promising as a power source for wearable devices with multifunctions ranging from sensing to locomotion. Achieving mechanical robustness and high power conversion efficiency for ultraflexible OPVs is essential for their successful application. However, it is challenging to simultaneously achieve these features by the difficulty to maintain stable performance under a microscale bending radius. Ultraflexible OPVs are proposed by employing a novel metal‐oxide‐free cathode that consists of a printed ultrathin metallic transparent electrode and an organic electron transport layer to achieve high electron‐collecting capabilities and mechanical robustness. In fact, the proposed ultraflexible OPV achieves a power conversion efficiency of 9.7% and durability with 74% efficiency retention after 500 cycles of deformation at 37% compression through buckling. The proposed approach can be applied to active layers with different morphologies, thus suggesting its universality and potential for high‐performance ultraflexible OPV devices.     

Tuning Contact Resistance in Top‐Contact p‐Type and n‐Type Organic Field Effect Transistors by Self‐Generated Interlayers

Contact resistance significantly limits the performance of organic field‐effect transistors (OFETs). Positioning interlayers at the metal/organic interface can tune the effective work‐function and reduce contact resistance. Myriad techniques offer interlayer processing onto the metal pads in bottom‐contact OFETs. However, most methods are not suitable for deposition on organic films and incompatible with top‐contact OFET architectures. Here, a simple and versatile methodology is demonstrated for interlayer processing in both p‐ and n‐type devices that is also suitable for top‐contact OFETs. In this approach, judiciously selected interlayer molecules are co‐deposited as additives in the semiconducting polymer active layer. During top contact deposition, the additive molecules migrate from within the bulk film to the organic/metal interface due to additive‐metal interactions. Migration continues until a thin continuous interlayer is completed. Formation of the interlayer is confirmed by X‐ray photoelectron spectroscopy (XPS) and cross‐section scanning transmission electron microscopy (STEM), and its effect on contact resistance by device measurements and transfer line method (TLM) analysis. It is shown that self‐generated interlayers that reduce contact resistance in p‐type devices, increase that of n‐type devices, and vice versa, confirming the role of additives as interlayer materials that modulate the effective work‐function of the organic/metal interface.     

Solution‐Processed,Alkali Metal‐Salt‐Doped,Electron‐Transport Layers for High‐Performance Phosphorescent Organic Light‐Emitting Diodes

High‐performance, blue, phosphorescent organic light‐emitting diodes (PhOLEDs) are achieved by orthogonal solution‐processing of small‐molecule electron‐transport material doped with an alkali metal salt, including cesium carbonate (Cs₂CO₃) or lithium carbonate (Li₂CO₃). Blue PhOLEDs with solution‐processed 4,7‐diphenyl‐1,10‐phenanthroline (BPhen) electron‐transport layer (ETL) doped with Cs₂CO₃ show a luminous efficiency (LE) of 35.1 cd A^?1 with an external quantum efficiency (EQE) of 17.9%, which are two‐fold higher efficiency than a BPhen ETL without a dopant. These solution‐processed blue PhOLEDs are much superior compared to devices with vacuum‐deposited BPhen ETL/alkali metal salt cathode interfacial layer. Blue PhOLEDs with solution‐processed 1,3,5‐tris(m‐pyrid‐3‐yl‐phenyl)benzene (TmPyPB) ETL doped with Cs₂CO₃ have a luminous efficiency of 37.7 cd A^?1 with an EQE of 19.0%, which is the best performance observed to date in all‐solution‐processed blue PhOLEDs. The results show that a small‐molecule ETL doped with alkali metal salt can be realized by solution‐processing to enhance overall device performance. The solution‐processed metal salt‐doped ETLs exhibit a unique rough surface morphology that facilitates enhanced charge‐injection and transport in the devices. These results demonstrate that orthogonal solution‐processing of metal salt‐doped electron‐transport materials is a promising strategy for applications in various solution‐processed multilayered organic electronic devices.     

Intercalation‐Induced Tunable Stimuli‐Responsive Color‐Change Properties of Crystalline Organic Layered Compound

Layered structures accommodate guest molecules and ions in the interlayer space through intercalation. Organic layered compounds, such as layered polymers, have both intercalation and dynamic properties. Here intercalation‐induced tunable temperature‐ and mechanical‐stress‐responsive color‐change properties of crystalline layered polydiacetylene (PDA) as an organic layered compound are reported. In general, organic materials with stimuli responsivity are developed by molecular design and synthesis. In the present work, intercalation of guest metal cations in the layered PDA directs tuning of the stimuli‐responsive color‐change properties, such as color, responsivity, and reversibility. Whereas PDA without intercalation of metal ions distinctly changes the color from blue to red at the threshold temperature, the PDA with intercalation of the divalent metal ions (PDA‐M²⁺) shows a variety of color‐change properties. The present study indicates that intercalation has versatile potentials for functionalization of organic layered compounds.     

Unidirectional High‐Power Generation via Stress‐Induced Dipole Alignment from ZnSnO3 Nanocubes/Polymer Hybrid Piezoelectric Nanogenerator

The extremely stable high‐power generation from hybrid piezoelectric nanogenerator (HP‐NG) based on a composite of single‐crystalline piezoelectric perovskite zinc stannate (ZnSnO₃) nanocubes and polydimethylsiloxane without any electrical poling treatment is reported. The HP‐NG generates large power output under only vertical compression, while there is negligible power generation with other configurations of applied strain, such as bending and folding. This unique high unidirectionality of power generation behavior of the HP‐NG provides desirable features for large‐area piezoelectric power generation based on vertical mechanical compression such as moving vehicles, railway transport, and human walking. The HP‐NGs of ZnSnO₃ nanocubes exhibit high mechanical durability, excellent robustness, and high power‐generation performance. A large recordable output voltage of about 20 V and an output current density value of about 1 μA cm^?2 are successfully achived, using a single cell of HP‐NG obtained under rolling of a vehicle tire.     

Development of a Unique Class of Spiro‐Type Two‐Photon Functional Fluorescent Dyes and Their Applications for Sensing and Bioimaging

Spiro compounds with rigid structures have attracted significant attention in the recent years due to their useful applications in diverse fields such as asymmetric catalysis and organic optoelectronic materials. However, spiro cores have not yet been employed as the spiro‐type two‐photon fluorescent dyes in the aspects of sensing and bioimaging. Therefore, the spiro‐type two‐photon fluorescent dyes with excellent two‐photon properties are highly sought after. Here, a unique class of spiro‐type two‐photon fluorescent dyes ( STP ) is engineered and applied in sensing and bioimaging. The studies indicate that the novel STP fluorescent dyes have favorable two‐photon properties from the point view of spiro compounds. By exploiting the superior two‐photon optical properties of the STP dyes, the first two‐photon ratiometric HOCl fluorescent probe STP‐HClO for sensing and imaging HOCl in the living cells and living tissues is constructed, demonstrating the profound value of the new STP dyes for the unprecedented development of the sprio‐type fluorescent sensing and imaging agents. It is believed that the innovative STP dyes may pave the way for designing more efficient spiro‐type two‐photon fluorescent probes and organic optoelectronic materials as well.     

Large‐Scale Fabrication of Three‐Dimensional Surface Patterns Using Template‐Defined Electrochemical Deposition

A new strategy to achieve large‐scale, three‐dimensional (3D) micro‐ and nanostructured surface patterns through selective electrochemical growth on monolayer colloidal crystal (MCC) templates is reported. This method can effectively create large‐area (>1 cm²), 3D surface patterns with well‐defined structures in a cost‐effective and time‐saving manner (<30 min). A variety of 3D surface patterns, including semishells, Janus particles, microcups, and mushroom‐like clusters, is generated. Most importantly, our method can be used to prepare surface patterns with prescribed compositions, such as metals, metal oxides, organic materials, or composites (e.g., metal/metal oxide, metal/polymer). The 3D surface patterns produced by our method can be valuable in a wide range of applications, such as biosensing, data storage, and plasmonics. In a proof‐of‐concept study, we investigated, both experimentally and theoretically, the surface‐enhanced Raman scattering (SERS) performance of the fabricated silver 3D semishell arrays.     

Supramolecular Assembly of Perylene Bisimide with β‐Cyclodextrin Grafts as a Solid‐State Fluorescence Sensor for Vapor Detection

A nanoscopic supramolecular aggregate is constructed from perylene bisimide‐bridged bis‐(permethyl‐β‐cyclodextrins) 1 via π–π stacking interactions. Its self‐assembly behavior in organic and aqueous solutions is investigated by UV–Vis, fluorescence, and ¹H NMR spectroscopy. Transmission electron microscopy and scanning electron microscopy images show the 1D nanorod aggregation of 1 , which is birefringent under crossed polarizer conditions and strongly fluorescent as depicted in the fluorescence microscopy image. X‐ray powder diffraction measurements indicate that 1 forms a well‐ordered crystalline arrangement with a π–π stacking distance of 4.02 Å. Furthermore, the solid‐state fluorescence sensing is explored by utilizing the poly(vinylidene fluoride) membrane‐embedded 1 , giving that 1 , as a novel vapor detecting material, can probe several kinds of volatile organic compounds and, especially, exhibits high sensitivity to organic amines.     

The Swiss‐Army‐Knife Self‐Assembled Monolayer: Improving Electron Injection,Stability, and Wettability of Metal Electrodes with a One‐Minute Process

A novel Self‐assembled Monolayer (SAM) forming molecule bisjulolidyldisulfide (9,9'‐disulfanediylbis(2,3,6,7‐tetrahydro‐1H,5H‐pyrido[3,2,1‐ij]quinoline)) is demonstrated which lowers the work function of metal surfaces by ≈1.2 eV and can be deposited in a 1 min process. Bisjulolidyldisulfide exists in a stable disulfide configuration prior to surface exposure and can therefore be stored, handled, and processed in ambient conditions. SAM from bisjulolidyldisulfide are deposited on metal surfaces (Au and Ag), including inkjet printed Ag on polyethylene terephthalate substrates, investigated by photoelectron and infrared spectroscopy, and used as electrodes in n‐type organic field effect transistor (OFET). Treatment of electrodes in OFET devices with with bisjulolidyldisulfide‐SAMs reduces the contact resistance by two orders of magnitude and improves shelf life with respect to pristine metal electrodes. The presented treatment also increases the surfaces wettability and thereby facilitates solution processing of a subsequent layer. These beneficial properties for device performance, processing, and stability, combined with ease of preparation and handling, render this SAM‐forming molecule an excellent candidate for the high‐throughput production of flexible electronic devices.     

Optimal Structure for High‐Performance and Low‐Contact‐Resistance Organic Field‐Effect Transistors Using Contact‐Doped Coplanar and Pseudo‐Staggered Device Architectures

A low contact resistance achieved on top‐gated organic field‐effect transistors by using coplanar and pseudo‐staggered device architectures, as well as the introduction of a dopant layer, is reported. The top‐gated structure effectively minimizes the access resistance from the contact to the channel region and the charge‐injection barrier is suppressed by doping of iron(III)trichloride at the metal/organic semiconductor interface. Compared with conventional bottom‐gated staggered devices, a remarkably low contact resistance of 0.1–0.2 kΩ cm is extracted from the top‐gated devices by the modified transfer line method. The top‐gated devices using thienoacene compound as a semiconductor exhibit a high average field‐effect mobility of 5.5–5.7 cm² V^?1 s^?1 and an acceptable subthreshold swing of 0.23–0.24 V dec^?1 without degradation in the on/off ratio of ≈10⁹. Based on these experimental achievements, an optimal device structure for a high‐performance organic transistor is proposed.     

Electrowetting‐Induced Morphological Evolution of Metal‐Organic Inverse Opals toward a Water‐Lithography Approach

This paper presents a unique morphological evolution of metal‐organic inverse opals (Pb(NO₃)₂‐poly(St‐MMA‐AA)) subjected to an electrowetting process. The morphology of the building blocks changes from interconnected pores to separated hollow spheres during the electrowetting process, accompanied by an unusual blue‐shift of the stopband position and the decreased wettability of the film. This morphology evolution is attributed to the simultaneous collapse/reconstruction of the metal‐organic frame owing to the partial dissolution of the metal salt and the interfacial assembly of the metal‐organic coordination around the skeleton. The adjustable morphology can be developed as a novel and simple water‐lithography approach for the creation of the photonic crystal pattern.     

Metal‐Organic‐Framework‐Coated Optical Fibers as Light‐Triggered Drug Delivery Vehicles

Physical delivery of anticancer drugs in controlled anatomic locations can complement the advances being made in chemo‐selective therapies. To this end, an optical fiber catheter is coated in a thin layer of metal organic framework UiO‐66 and the anticancer drug 5‐Fluorouracil (5‐FU) is deposited within the pores. Delivery of light of appropriate wavelength through the fiber catheter is found to trigger the release of 5‐FU on demand, offering a new route to localized drug administration. The system exhibits great potential with as much as 110 × 10^?6 m of 5‐FU delivered within 1 min from one fiber.     

Fabrication of Sub‐10 nm Metallic Lines of Low Line‐Width Roughness by Hydrogen Reduction of Patterned Metal–Organic Materials

The fabrication of very narrow metal lines by the lift‐off technique, especially below sub‐10 nm, is challenging due to thinner resist requirements in order to achieve the lithographic resolution. At such small length scales, when the grain size becomes comparable with the line‐width, the built‐in stress in the metal film can cause a break to occur at a grain boundary. Moreover, the line‐width roughness (LWR) from the patterned resist can result in deposited metal lines with a very high LWR, leading to an adverse change in device characteristics. Here a new approach that is not based on the lift‐off technique but rather on low temperature hydrogen reduction of electron‐beam patterned metal naphthenates is demonstrated. This not only enables the fabrication of sub‐10 nm metal lines of good integrity, but also of low LWR, below the limit of 3.2 nm discussed in the International Technology Roadmap for Semiconductors. Using this method, sub‐10 nm nickel wires are obtained by reducing patterned nickel naphthenate lines in a hydrogen‐rich atmosphere at 500 °C for 1 h. The LWR (i.e., 3 σ_LWR) of these nickel nanolines was found to be 2.9 nm. The technique is general and is likely to be suitable for fabrication of nanostructures of most commonly used metals (and their alloys), such as iron, cobalt, nickel, copper, tungsten, molybdenum, and so on, from their respective metal–organic compounds.     

Single‐Step Deposition of Au‐ and Pt‐Nanoparticle‐Functionalized Tungsten Oxide Nanoneedles Synthesized Via Aerosol‐Assisted CVD,and Used for Fabrication of Selective Gas Microsensor Arrays

Tungsten oxide nanostructures functionalized with gold or platinum NPs are synthesized and integrated, using a single‐step method via aerosol‐assisted chemical vapour deposition, onto micro‐electromechanical system (MEMS)‐based gas‐sensor platforms. This co‐deposition method is demonstrated to be an effective route to incorporate metal nanoparticles (NP) or combinations of metal NPs into nanostructured materials, resulting in an attractive way of tuning functionality in metal oxides (MOX). The results show variations in electronic and sensing properties of tungsten oxide according to the metal NPs introduced, which are used to discriminate effectively analytes (C₂H₅OH, H₂, and CO) that are present in proton‐exchange fuel cells. Improved sensing characteristics, in particular to H₂, are observed at 250 °C with Pt‐functionalized tungsten oxide films, whereas non‐functionalized tungsten oxide films show responses to low concentrations of CO at low temperatures. Differences in the sensing characteristics of these films are attributed to the different reactivities of metal NPs (Au and Pt), and to the degree of electronic interaction at the MOX/metal NP interface. The method presented in this work has advantages over other methods of integrating nanomaterials and devices, of having fewer processing steps, relatively low processing temperature, and no requirement for substrate pre‐treatment.