Organic field‐effect transistors based on aligned small molecule semiconductors have shown high charge carrier mobilities in excess of 10 cm2 V−1 s−1. This makes them a viable alternative to ...amorphous inorganic semiconductors especially if a high reproducibility can be achieved. Here, the optimization of high mobility organic field‐effect transistors based on the organic semiconductor 2,7‐dioctyl1benzothieno3,2‐b benzothiophene (C8‐BTBT) via the addition of a polymer additive to the printing solution is reported. Specifically, films and devices are compared based on solutions of the neat semiconductor and the blend with polystyrene and shear‐coated devices with excellent device characteristics and gate‐voltage‐independent mobility values reaching 12 cm2 V−1 s−1 are shown, which are the highest reported values for C8‐BTBT‐based films prepared by a scalable, solution‐based process.
Organic field‐effect transistors with semiconductor films prepared by solution shearing and high charge carrier mobilities are presented. By blending the small molecule semiconductor 2,7‐dioctyl1benzothieno3,2‐b benzothiophene (C8‐BTBT) with polystyrene, both the carrier mobility and the reproducibility of the devices are improved compared to devices with the neat semiconductor.
Metal-halide perovskite thin monocrystals featuring efficient carrier collection and transport capabilities are well suited for radiation detectors, yet their growth in a generic, well-controlled ...manner remains challenging. Here, we reveal that mass transfer is one major limiting factor during solution growth of perovskite thin monocrystals. A general approach is developed to overcome synthetic limitation by using a high solute flux system, in which mass diffusion coefficient is improved from 1.7×10
to 5.4×10
m
s
by suppressing monomer aggregation. The generality of this approach is validated by the synthesis of 29 types of perovskite thin monocrystals at 40-90 °C with the growth velocity up to 27.2 μm min
. The as-grown perovskite monocrystals deliver a high X-ray sensitivity of 1.74×10
µC Gy
cm
without applied bias. The findings regarding limited mass transfer and high-flux crystallization are crucial towards advancing the preparation and application of perovskite thin monocrystals.
Organic-inorganic halide perovskite has attracted significant interest in being switching medium for resistive random access memory (RRAM), yet the in-depth understanding of ion spatial distribution ...and transport kinetics—which is responsible for the filament formation and normally suffers from a paradox between stochasticity and dynamics—remains limited. Herein, we show evidence of space-confined, fast extrinsic ion transport within grain boundaries (GBs) of two-dimensional perovskite films through systematic
ex-situ
and
in-situ
studies. The filament growth can be dominated by the geometrical feature of GBs that act as the channel for cation transport in the dielectric film. By tailoring the structure of perovskite GBs, electroforming-free RRAM devices are fabricated with an ultralow set voltage of 0.09 V (1.8kVcm
−1
) and small temporal/spatial variations (<10%). The devices can also be integrated with flexible substrates for multifunctional applications, including multilevel writing and light erasing. Our work may open new perspectives for regulating filament formation kinetics in RRAMs and provides a reliable building block for future applications in electronic and photonic circuits.
Low‐voltage organic field‐effect transistors (OFETs) are of great interest for organic electronics applications that require low power consumption such as wearable electronics, biomedical ...applications, or mobile electronics. In this work, an approach leading to transistors fabricated from solution with high charge carrier mobilities operating at voltages < 1 V is presented. By blending the small‐molecule semiconductor 6,13‐bis(triisopropylsilyl‐ethynyl)pentacene (TIPS‐pentacene) with polystyrene it is possible to achieve good film coverage and uniformity as well as ultrathin semiconductor films. This reduction in thickness relative to neat films results in a high fraction of the high‐mobility polymorph of TIPS‐pentacene and excellent film morphologies with continuous highly crystalline domains. OFETs using SiO2 as the dielectric with average hole mobilities as high as 8.3 cm2 V−1 s−1 and maximum mobilities of up to 12.3 cm2 V−1 s−1 which favorably compares with the previous record for TIPS‐pentacene, especially when considering the simplicity of the approach, are demonstrated. By depositing the optimized semiconductor blends on solution‐based polymer dielectric layers of polyvinylphenol, cross‐linked with 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, a record‐high mobility of 4.2 cm2 V−1 s−1 for solution‐processed, ultralow‐voltage OFET devices (operating at <1 V) is obtained.
The best charge carrier mobility for solution‐processed organic field‐effect transistors operating at ultralow voltage is reported herein. The fabrication process and characterization of optimized shear coating blends of 6,13‐bis(triisopropylsilylethynyl)pentacene and polystyrene are shown, obtaining average charge carrier mobilities of 4.2 cm2 V−1 s−1 for devices operating under 1 V.
The emergence of lead halide perovskites as light absorbers has enabled low cost and efficient photovoltaics via a simple solution, high‐throughout process. However, the perovskite materials suffer ...from instability under various environmental stressors, including moisture, oxygen, heat, and irradiation, which heavily hinders the practical application of perovskite solar cells (PSCs). In this review, the structural and performance instability of perovskites and their degradation causes and mechanisms under different conditions are discussed. The state‐of‐the‐art strategies that stabilize the perovskite layer in solar cells are then summarized; moreover, the microscopic reasons for the improved environmental tolerance are elucidated. Due to the structural tunability of perovskites, the environmental tolerance, which is influenced by defects and extended imperfections in the polycrystalline films, can be enhanced by varying intrinsic factors of component, dimensionality, and crystallinity. Furthermore, the extrinsic factors to improve the environmental tolerance of perovskites are portrayed in terms of surface functionalized molecules, barrier layers, and encapsulants. The mechanism of each method in reducing the environmental sensitivity is highlighted to provide potential guidance in extending the lifetime of perovskite devices.
Organic–inorganic hybrid perovskite solar cells (PSCs) have emerged as a promising technology for the next‐generation photovoltaic. The instability of PSCs is addressed as the major barrier to commercialization. This review covers the recent progress on strategies of stabilizing perovskite layers and discusses the microscopic mechanism for improved environmental tolerance. A personal perspective on the research direction of stable PSCs is provided.
Accurate forecasting of wind power is crucial for efficiently scheduling power grids that incorporate wind energy. However, distribution instability of time-varying data can undermine the ...generalization capability of forecasting models in future periods. This paper introduces a transfer learning approach incorporating adversarial training and temporal convolution to address wind power forecasting from the distribution-centric perspective. The proposed approach can be divided into two joint modules: the temporal domain split and domain-adversarial temporal convolutional network. The former segregates training data into temporal domains characterized by the most significant distribution differences, while the latter aims is designed to learn shared knowledge from the segmented temporal domains. The shared knowledge is independent of distribution shifts, which can be generalized to future testing well. Specifically, the domain-adversarial temporal convolutional network is composed of a base model incorporating temporal convolutional network and a domain classifier. Both components are jointly optimized by minimizing power prediction loss and maximizing temporal domain classification loss. The data from actual wind turbines are employed to validate the proposed approach. Experimental results show that the superior performance of the proposed approach compared to benchmark models, achieving a remarkable 24.56% improvement in accuracy by introducing adversarial training.
Abstract Multispectral imaging that captures multiple band information for effective environmental or object identification is of great interest in medical, vision, military, and space applications. ...Monolithic stacked detectors based on epitaxial electronics have been the principal option for infrared dual‐band imagers. However, the integration of these single‐band units would inevitably lead to performance reduction, high fabrication cost, and low reproducibility yield, which limits the widespread application of such technology. Here, a high‐throughput blade coating process is demonstrated to fabricate monolithic double‐perovskite‐layer photodiodes with preferential crystallographic morphology and high reproductivity. The device delivers electrically switchable dual‐band response with a dark current below 10 −9 mA cm −2 , a selective spectral response of 300–1100 nm, and bandwidths of 16.5/>20 MHz for two distinct bands. Furthermore, such device configuration can concurrently capture dual‐color spectral information under an AC‐driven mode, enabling the complementary dual‐spectral imaging for bioimaging and environmental monitoring.
Understanding the degradation mechanism of perovskite solar cells (PSCs) is of particular importance to solve their instability issue, which is one of the major hindrances toward commercialization. ...Here, it is shown that a halide diffusion equilibrium exists at the heterointerface of perovskite devices, which strongly impacts the evolution of device performance. The combined experimental and theoretical studies reveal that halide components diffuse from perovskite to fullerene layers in a p‐i‐n PSC device and equilibrate with an iodine density of 1018–1019 cm−3 within 80 h under dark aging condition. It is found that there is a strong correction between the device efficiency and halide diffusion equilibrium of PSCs, as the diffused halides can chemically dope the transport layer and result in the nonstoichiometric perovskite surface, leading to both initial enhancement and long‐term loss of the photovoltaic efficiency of solar cells. In response to this issue, a predoping strategy is developed to attain the halide diffusion equilibrium once the device is fabricated, thereby avoiding the further halide migration and initial efficiency variations. As a result, the as‐prepared PSC achieved an efficiency of 23.13% as well as stable power output under continuous one sun illumination.
The halide diffusion from perovskite can chemically dope the electron transport layer and bring forth the nonstoichiometric surface, leading to initial enhancement but long‐term loss of the photovoltaic efficiency of p‐i‐n cells. A predoping strategy is developed to reach the diffusion equilibrium state for the fresh‐fabricated device and delivers a power conversion efficiency of 23.13% with stable power output.
Organic electronic devices such as light-emitting diodes, solar cells or rectifying diodes normally have a sandwich layer architecture stacked between the electrodes in a crossbar layout. Often ...however, the side effects of operating the devices in such an arrangement are either ignored or give rise to misinterpretations regarding the device performance or layer quality. For the sake of simplicity, device currents are typically assumed to exclusively flow in the direction vertical to the substrate, even though the conductivity of doped organic layers is high and gives rise to significant lateral current flows. Here, we study the vertical and lateral charge up along the n-doped and the p-doped layers as well as the resulting capacitance increase of charging the intrinsic layer outside the active area. We observe that controlling such lateral charging by structuring the doped layers can reduce the leakage current dramatically. We employ impedance spectroscopy to investigate the lateral charging responsibility for the capacitance increase at low frequencies. Modeling of the devices by a distributed RC circuit model yields information about the thickness, the conductivity, and the corresponding activation energy of both, the n-doped and the p-doped layers, simultaneously. We demonstrate that the capacitive effects from lateral charging can easily be misinterpreted as trap states in capacitance frequency characteristics. However, correct analysis with the proposed model actually yields rich and detailed post-fabrication information which can be utilized in device failure and degradation tests. Moreover, our results will aid the design and characterization of new electronic devices where lateral charge flow is part of the device concept.
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•Centimeter scale lateral charging due to doped layers is studied.•Low leakage current is achieved by structuring the doped layers.•An RC circuit model describes the low frequency capacitance increase.•The conductivity of the doped layers is measured for finished OLEDs.
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