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Ligand crosslinking in QD systems has shown promise for developing robust QD films for applications in high-resolution displays. The kinetics and mechanism of ligand crosslinking can be described using experimentally validated kinetic Monte Carlo model.

An inorganic p-type CuInS2 semiconductor was combined with the semiconducting polymer of PNDI3OT-Se1 and PNDI3OT-Se2 with different HOMO/LUMO levels for photoelectrochemical hydrogen production. Charge transfer behaviors at polymer/CuInS2 junctions were investigated by electrochemical impedance spectroscopy. The heterojunction of p-CuInS2 and n-type polymer (both PNDI3OT-Se1 and Se2) successfully made p-n junctions and showed improved charge transfer. However, we found that higher HOMO levels of polymer than valence band maximum (VBM) of CuInS2 spurred charge recombination at interfaces. As a result, CuInS2 /PNDI3OT-Se1/TiO2 /Pt, which has suitable energy levels matched between PNDI3OT-Se1 and CuInS2 , shows photocurrent (-15.67 mA cm-2 ) improved concretely when compared to a CuInS2 /TiO2 /Pt photoelectrode (-7.11 mA cm-2 ) at 0.0 V vs. RHE applied potential. Additionally, the photoelectrochemical stability of CuInS2 /PNDI3OT-Se1/TiO2 /Pt photoelectrode was also investigated.

We report on high-performance polymeric field-effect transistors (PFETs) operating at low voltages (Vop) using a self-assembled monolayer (SAM)-passivated HfOx dielectric layer. A diketopyrrolopyrrole and quaterthiophene-based copolymer (PDPP2DT-T2) was spin-coated in air as an active channel material on top of a HfOx gate dielectric that was passivated with n-octyltrichlorosilane (OTS), n-octadecyltrichlorosilane (ODTS), and n-dodecylphosphonic acid (PAC12) SAMs. The high capacitance and low leakage current of the SAM-passivated HfOx dielectrics enabled the devices to operate at |Vop| of less than 4 V. In particular, the PFETs using ODTS-passivated HfOx demonstrated a high hole mobility (μeffh) of 1.98 cm2 V−1 s−1, a current on/off ratio of 1.4 × 104, and a threshold voltage of −0.8 V despite the fact that the device fabrication and all measurements were conducted under ambient conditions without encapsulation. Moreover, the μeffh value observed in this study is the best for high-k-dielectric-based low-voltage PFETs reported to date. This work demonstrates that our facile modification of high-k dielectrics with SAMs is a highly effective method for realizing high-performance semiconducting copolymer-based transistors working at a low Vop regime with low power consumption.

Electroluminescence from quantum dots (QDs) is a suitable photon source for futuristic displays offering hyper-realistic images with free-form factors. Accordingly, a nondestructive and scalable process capable of rendering multicolored QD patterns on a scale of several micrometers needs to be established. Here, nondestructive direct photopatterning for heavy-metal-free QDs is reported using branched light-driven ligand crosslinkers (LiXers) containing multiple azide units. The branched LiXers effectively interlock QD films via photo-crosslinking native aliphatic QD surface ligands without compromising the intrinsic optoelectronic properties of QDs. Using branched LiXers with six sterically engineered azide units, RGB QD patterns are achieved on the micrometer scale. The photo-crosslinking process does not affect the photoluminescence and electroluminescence characteristics of QDs and extends the device lifetime. This nondestructive method can be readily adapted to industrial processes and make an immediate impact on display technologies, as it uses widely available photolithography facilities and high-quality heavy-metal-free QDs with aliphatic ligands.

An inorganic p-type CuInS

Establishing multi-colour patterning technology for colloidal quantum dots is critical for realising high-resolution displays based on the material. Here, we report a solution-based processing method to form patterns of quantum dots using a light-driven ligand crosslinker, ethane-1,2-diyl bis(4-azido-2,3,5,6-tetrafluorobenzoate). The crosslinker with two azide end groups can interlock the ligands of neighbouring quantum dots upon exposure to UV, yielding chemically robust quantum dot films. Exploiting the light-driven crosslinking process, different colour CdSe-based core-shell quantum dots can be photo-patterned; quantum dot patterns of red, green and blue primary colours with a sub-pixel size of 4 μm × 16 μm, corresponding to a resolution of >1400 pixels per inch, are demonstrated. The process is non-destructive, such that photoluminescence and electroluminescence characteristics of quantum dot films are preserved after crosslinking. We demonstrate that red crosslinked quantum dot light-emitting diodes exhibiting an external quantum efficiency as high as 14.6% can be obtained., Designing high-resolution displays based on colloidal quantum dots remains a challenge. Here, the authors demonstrate a photo-patterning method to develop CdSe-based core-shell quantum dots patterns of red, green and blue colours with diameters ranging from 7 to 20 nm and resolution of 1400 pixels per inch.

We designed and synthesized regio-regular alternating diketopyrrolopyrrole (DPP)-based D1–A–D2–A terpolymers (PDPPF2T2DPP-T2, PDPPF2T2DPP-TVT, and PDPPF2T2DPP-DTT) using a primary donor (D1) [3,3′-difluoro-2,2′-bithiophene (F2T2)] and a secondary donor (D2) [2,2′-bithiophene (T2), (E)-1,2-di(thiophen-2-yl)ethene (TVT), or dithieno[3,2-b:2′,3′-d]thiophene (DTT)]. A PDPP2DT-F2T2 D–A polymer was synthesized as well to compare optical, electronic, and photovoltaic properties. The absorption peaks of the terpolymers (PDPPF2T2DPP-T2, PDPPF2T2DPP-TVT, and PDPPF2T2DPP-DTT) were longer (λmax = 801–810 nm) than the peak of the PDPP2DT-F2T2 polymer (λmax = 799 nm), which is associated with the high-lying HOMO levels of the terpolymers (−5.08 to −5.13 eV) compared with the level of the PDPP2DT-F2T2 polymer (−5.38 eV). The photovoltaic properties of these DPP-based polymers were investigated under simulated AM 1.5G sunlight (100 mW cm−2) with a conventional structure (ITO/PEDOT:PSS/polymer:PC71BM/Al). The open-circuit voltages (Voc) of photovoltaic devices containing the terpolymers were slightly lower (0.68–0.70 V) than the Voc of the device containing the PDPP2DT-F2T2 polymer (0.79 V). The short-circuit current (Jsc) of the PDPPF2T2DPP-DTT device was significantly improved (14.14 mA cm−2) compared with that of the PDPP2DT-F2T2 device (8.29 mA cm−2). As a result, the power conversion efficiency (PCE) of the PDPPF2T2DPP-DTT device (6.35%) was increased by 33% compared with that of the simple D–A-type PDPP2DT-F2T2 device (4.78%). The highest Jsc and PCE values (the PDPPF2T2DPP-DTT device) were attributed to an optimal nanoscopically mixed morphology and strong interchain packing with a high face-on orientation in the blend film state. The study demonstrated that our strategy of using multiple donors in a regio-regular alternating fashion could fine-tune the optical, electronic, and morphological properties of D–A-type polymers, enhancing the performance of polymer solar cells.

We developed a patternable synthesis method of wafer-scale NbS2, which can be applied for the fabrication of source and drain electrodes of p- and n-type organic field-effect transistors (OFETs) and logic gates. NbS2 film with high uniformity was synthesized directly on a 2-in Si wafer. NbS2 patterns of various sizes and shapes were readily synthesized onto an entire wafer. OFETs with NbS2 electrodes exhibited superior performances to those with conventional metal electrodes. The superior performance of the former OFETs was primarily a result of the enhanced crystallinity of the organic semiconductor layer deposited onto the NbS2 electrode surface. Furthermore, organic complementary circuits such as NOT, NAND, and NOR gates were successfully assembled using the resulting OFETs as a proof of applicability of these devices to complex logic circuits.

Lepton-flavor violation (LFV) has been discovered in the neutrino sector by neutrino oscillation experiments. The minimal extension of the Standard Model (SM) to include neutrino masses allows LFV in the charged sector (CLFV) at the loop level, but at rates that are too small to be experimentally observed. Lepton-number violation (LNV) is explicitly forbidden even in the minimally extended SM, so the observation of an LNV process would be unambiguous evidence of physics beyond the SM. The search for the LNV and CLFV process μ−+N(A,Z)→e++N′(A,Z−2) (referred to as μ−→e+) complements 0νββ decay searches, and is sensitive to potential flavor effects in the neutrino mass-generation mechanism. A theoretical motivation for μ−→e+ is presented along with a review of the status of past μ−→e+ experiments and future prospects. Special attention is paid to an uncertain and potentially dominant background for these searches, namely, radiative muon capture (RMC). The RMC high energy photon spectrum is theoretically understudied and existing measurements insufficiently constrain this portion of the spectrum, leading to potentially significant impacts on current and future μ−→e+ work.

Early detection of internal short circuits (ISC) in Lithium-Ion Batteries (LIBs) is crucial for avoiding potential catastrophes. State-of-the art health monitoring methods fall short in terms of their ability to detect early-stage short circuits and in terms of ease of implementation. We report a unique internal-short circuit detection method, capable of detecting early-stage short circuits. A set of electrochemically curated pulse current probes, activated at predetermined states of charge (SOC), accurately determine the short-induced leakage current by comparing with an on-board physics based electrochemical-thermal reduced order model, that considers characteristic non-linear behaviour of LIBs. These specially designed diagnostic probes act as a ‘treadmill’ test, which detect soft short and estimates the soft short resistance accurately. Importantly, we demonstrate its ability to detect, estimate both internal short and ageing-related battery degradation, even when both are present. Proof-of-concept experiments on commercial batteries show our method's ability to detect soft short (up to 200Ω) and ageing extents (>90%) with >98% accuracy. Anchored in underlying electrochemical processes of the battery, we provide a detailed analysis on how and why this method is uniquely positioned as an accurate, practically implementable health and safety monitoring algorithm on a battery management system.

In this manuscript, the fabrication of polymer nonvolatile memory cells based on one-transistor–one-transistor (1T1T) device geometries is reported. A spin-coated diketopyrrolopyrrole (DPP)-based polymer semiconductor was used as the active channel layer for both the control transistor (CT) and memory transistor (MT); thermally deposited gold nanoparticles (Au NPs) were inserted between the tunneling and blocking gate dielectrics as a charge-trapping layer of the MT. In the 1T1T memory cell, the source electrode of the CT was connected to the gate electrode of the MT, while the drain electrode of the MT was connected to the gate electrode of the CT. The reading and writing processes of the memory cells operated separately, which yielded a nondestructive read-out capability. The fabricated 1T1T polymer memory cells exhibited excellent device performances with a large memory window of 16.1 V, a high programming–erasing current ratio >103, a long retention of 103 s, a cyclic stability of 500 cycles, and a 2-...

High carrier mobilities have recently been achieved in polymer field effect transistors (FETs). However, many of these polymer FET devices require the use of chlorinated solvents such as chloroform (CF), chlorobenzene (CB), and o-dichlorobenzene (DCB) during fabrication. The use of these solvents is highly restricted in industry because of health and environmental issues. Here, we report the synthesis of a low band gap (1.43 eV, 870 nm) semiconducting polymer (PDPP2DT-F2T2) having a planar geometry, which can be readily processable with nonchlorinated solvents such as toluene (TOL), o-xylene (XY), and 1,2,4-trimethylbenzene (TMB). We performed structural characterization of PDPP2DT-F2T2 films prepared from different solvents, and the electrical properties of the films were measured in the context of FETs. The devices exhibited an ambipolar behavior with hole dominant transport. Hole mobilities increased with increasing boiling point (bp) of the nonchlorinated solvents: 0.03, 0.05, and 0.10 cm2 V–1 s–1 for...

A continuum-based approach for describing the plastic hardening behavior of magnesium alloy sheets subjected to non-proportional strain path changes at room temperature is presented. The constitutive model is based on an anisotropic distortional yield function that combines a stable component and a fluctuating component. The stable component initiates the yield criterion that characterizes the typical strength differential (SD) effect between tension and compression in magnesium alloys at room temperature. The evolution of the fluctuating component is reformulated based on its cubic metal counterpart to represent the deformation behavior of magnesium alloys, which consists of slip- and twinning-dominant deformation modes. To validate the proposed model, a predictor–corrector numerical algorithm was implemented in a finite element (FE) program by using a user material subroutine, and its numerical accuracy was evaluated by iso-error map analysis. Comparison of the experimental and simulated results obtained for various loading path changes showed that, although the model was not formulated using the kinematic hardening concept, the model could reproduce complex features of the stress–strain responses of an AZ31B magnesium alloy sheet under non-proportional loading paths, i.e., asymmetric hardening behavior under tension and compression, the sigmoidal nature of the hardening curve during monotonic compression and compression followed by tension.

Negative differential resistance/transconductance (NDR/NDT) has been attracting significant attention as a key functionality in the development of multivalued logic (MVL) systems that can overcome the limits of conventional binary logic devices. A high peak-to-valley current ratio (PVCR) and more than double-peak transfer characteristics are required to achieve a stable MVL operation. In this study, an organic NDR (ONDR) device with double-peak transfer characteristics and a high peak-to-valley current ratio (PVCR;10

An FPGA-based online trigger system has been developed for the COMET Phase-I experiment. This experiment searches for muon-to-electron conversion, which has never been observed yet. A drift chamber and trigger counters detect a mono-energetic electron from the conversion process in a 1-T solenoidal magnetic field. A highly intense muon source is applied to reach unprecedented experimental sensitivity. It also generates undesirable background particles, and a trigger rate due to these particles is expected to be much higher than an acceptable trigger rate in the data acquisition system. By using hit information from the drift chamber too, the online trigger system efficiently suppresses a background trigger rate while keeping signal-event acceptance large. A characteristic of this system is the utilization of the machine learning technique in the form of look-up tables on hardware. An initial simulation study indicates that the signal-event acceptance of the online trigger is 96% while the background trigger rate is reduced from over $90\,\mathrm{kHz}$ to $13\,\mathrm{kHz}$. For this scenario, we have produced trigger-related electronics that construct a distributed trigger architecture. The total latency of the trigger system was estimated to be $3.2\,\mathrm{\mu s}$, and the first operation test was carried out by using a part of the drift-chamber readout region., Comment: IEEE Real Time 2020 Conference, 7 pages

We designed and synthesized regio-regular alternating diketopyrrolopyrrole (DPP)-based D

Track finding with GPU-implemented fourth order Runge-Kutta (RK) method is investigated to track electrons from muon decay in the COMET drift chamber. In the COMET drift chamber, about 30-40 \% of signal events are composed of multiple turns where the right hit assignments to each turn partition are significant in the track finding. Scanning all possible track seeds can resolve the hit-to-track assignment problem with a high robustness about the noise hits, but requires a huge computational cost because of two reasons: 1) The adaptive RK method to propagate the electron track needs small global errors, corresponding to small step sizes. 2) Initial track seeds $(\theta, z, p_{x}, p_{y}, p_{z})$ have broad uncertainties, so many initial seeds should be tried and compared. In this presentation, these problems of massive computations are mitigated with 1) the parallel computing of RK track propagation, which assigns each track to each GPU block unit, 2) a better initial guess on the track seeds using the Hough transform and the geometrical property of the cylindrical drift chamber.

Electron donor (D)–acceptor (A)-type conjugated polymers (CPs) have emerged as promising semiconductor candidates for organic field-effect transistors. Despite their high charge carrier mobilities, optimization of electrical properties of D–A-type CPs generally suffers from complicated post-deposition treatments such as high-temperature thermal annealing or solvent-vapor annealing. In this work, we report a high-mobility diketopyrrolopyrrole-based D–A-type CP nanowires, self-assembled by a simple but very effective solvent engineering method that requires no additional processes after film deposition. In situ grown uniform nanowires at room temperature were shown to possess distinct edge-on chain orientation that is beneficial for lateral charge transport between source and drain electrodes in FETs. FETs based on the polymer nanowire networks exhibit impressive hole mobility of up to 4.0 cm2 V–1 s–1. Moreover, nanowire FETs showed excellent operational stability in high temperature up to 200 °C because of...

The Mu2e experiment will search for neutrinoless conversion of muons into electrons in the field of an aluminum nucleus. Precise and robust measurement of the outgoing electron momentum is an essential element to the experiment. We describe the design of a low mass tracking system to meet this requirement. We have chosen to use about 20,000 thin-walled Mylar straws held under tension to avoid the need for supports within the active volume. The electronics system enables the time-division technique to measure hit position along the wire. Charge will be measured using ADCs to provide particle identification capability.

We report high-performance top-gate bottom-contact flexible polymer field-effect transistors (FETs) fabricated by flow-coating diketopyrrolopyrrole (DPP)-based and naphthalene diimide (NDI)-based polymers (P(DPP2DT-T2), P(DPP2DT-TT), P(DPP2DT-DTT), P(NDI2OD-T2), P(NDI2OD-F2T2), and P(NDI2OD-Se2)) as semiconducting channel materials. All of the polymers displayed good FET characteristics with on/off current ratios exceeding 107. The highest hole mobility of 1.51 cm2 V–1 s–1 and the highest electron mobility of 0.85 cm2 V–1 s–1 were obtained from the P(DPP2DT-T2) and P(NDI2OD-Se2) polymer FETs, respectively. The impacts of the polymer structures on the FET performance are well-explained by the interplay between the crystallinity, the tendency of the polymer backbone to adopt an edge-on orientation, and the interconnectivity of polymer fibrils in the film state. Additionally, we demonstrated that all of the flexible polymer-based FETs were highly resistant to tensile stress, with negligible changes in their ...

The conservation of lepton flavor and total lepton number are no longer guaranteed in the Standard Model after the discovery of neutrino oscillations. The ${\ensuremath{\mu}}^{\ensuremath{-}}+N(A,Z)\ensuremath{\rightarrow}{e}^{+}+N(A,Z\ensuremath{-}2)$ conversion in a muonic atom is one of the most promising channels to investigate the lepton number violation processes, and measurement of the ${\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{-}{e}^{+}$ conversion is planned in future ${\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{-}{e}^{\ensuremath{-}}$ conversion experiments with a muonic atom in a muon-stopping target. This article discusses experimental strategies to maximize the sensitivity of the ${\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{-}{e}^{+}$ conversion experiment by introducing the new requirement of the mass relation of $M(A,Z\ensuremath{-}2)lM(A,Z\ensuremath{-}1)$, where $M(A,Z)$ is the mass of the muon-stopping target nucleus, to eliminate the backgrounds from radiative muon capture. The sensitivity of the ${\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{-}{e}^{+}$ conversion is expected to be improved by 4 orders of magnitude in forthcoming experiments using a proper target nucleus that satisfies the mass relation. The most promising isotopes found are $^{40}\mathrm{Ca}$ and $^{32}\mathrm{S}$.

In this Article, low-bandgap pTTDPP-BT polymers based on electron-accepting pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DPP) and benzothiadiazole (BT) and electron-donating thienothiophene (TT) moieties were synthesized. Phototransistors have been fabricated using ambipolar-behaving pTTDPP-BT polymers as active channel materials. The electrical and photoresponsive properties of the pTTDPP-BT phototransistors were strongly dependent on the film annealing temperature. As-spun pTTDPP-BT phototransistors exhibited a low hole mobility of 0.007 cm2/(V·s) and a low electron mobility of 0.005 cm2/(V·s), which resulted in low photocurrent detection due to the limited transport of the charge carriers. Thermal treatment of the polymer thin films led to a significant enhancement in the carrier mobilities (hole and electron mobilities of 0.066 and 0.115 cm2/(V·s), respectively, for 200 °C annealing) and thus significantly improved photoresponsive properties. The 200 °C-annealed phototransistors showed a wide-range wavelen...