Mosaic Charge Distribution-Based Sliding and Pressing Triboelectrification under Wavy Configuration.

As high-voltage output and fast response devices, triboelectric nanogenerators (TENGs) are widely used for sensors with fast and high-sensitivity performance. As a primary electrical signal, the waveform output provides an accurate and rapid response to external stimulus parameters such as press and slide. Here, based on mosaic charging and residual charge theories, the contact charging principle of TENGs is further discussed. Moreover, a wavy structure is obtained in the vertical contact separation and lateral sliding modes to further study the influence of external parameters applied to TENGs, which thus helps further the understanding of the output waveforms. The experimental results show that wavy TENGs have output properties that are excellent compared to those of TENGs with flat structures, such as longer charging and discharging times and more complex waveforms. By researching the waveform in depth, our work will provide new prospects for application in various sensors of interactive wearable systems, intelligent robots, and optoelectronic devices based on TENGs.

Polyferrocenylsilane Semicrystalline Polymer Additive for Solution-Processed p-Channel Organic Thin Film Transistors.

In this study, we demonstrated for the first time that a metal-containing semicrystalline polymer was used as an additive to mediate the thin film morphology of solution-grown, small-molecule organic semiconductors. By mixing polyferrocenylsilane (PFS) with an extensively-studied organic semiconductor 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene), PFS as a semicrystalline polymer independently forms nucleation and crystallization while simultaneously ameliorating diffusivity of the blend system and tuning the surface energies as a result of its partially amorphous property. We discovered that the resultant blend film exhibited a 6-fold reduction in crystal misorientation angle and a 3-fold enlargement in average grain width. Enhanced crystal orientation considerably reduces mobility variation, while minimized defects and trap centers located at grain boundaries lessen the adverse impact on the charge transport. Consequently, bottom-gate, top-contact organic thin film transistors (OTFTs) based on the TIPS pentacene/PFS mixture yielded a 40% increase in performance consistency (represented by the ratio of average mobility to the standard deviation of mobility). The PFS semicrystalline polymer-controlled crystallization can be used to regulate the thin film morphology of other high-performance organic semiconductors and shed light on applications in organic electronic devices.

Dynamic photonic perovskite light-emitting diodes with post-treatment-enhanced crystallization as writable and wipeable inscribers.

Controllable photonic patterns have attracted great attention for various applications in displays, smart sensors, and communications. Conventional patterned light-emitting-diode (LED) systems require complicated design, complex procedure, and advanced equipment. Moreover, permanent properties of the fabricated patterns on LED restrict it from various important applications. Herein, we present an innovative writable and wipeable perovskite light-emitting-diode (WWPeLED) device, which tactfully utilizes the large variation of turn-on voltage originating from the external quantum efficiency (EQE) difference under controllable thermal treatment. The turn-on voltages with/without thermal-treatment devices exhibit a large gap of over 5 V, and the thermal-treatment electroluminescence intensity is more than 10 times higher than that of non-thermal-treatment devices. The new phenomena open up an effective way of controlling illumination with desired pattern designs. Additionally, the distinct handwriting fonts and habits as well as printing patterns with illumination WWPeLED are also realized. Furthermore, these written and printed features can be totally wiped out with an 11 V cleaning voltage, turning the devices as a regular fully bright PeLED. The stability and repeatability tests prove the robustness of WWPeLED in both mechanical and electroluminescence performance after a long period of operations. The innovative WWPeLED devices may find prospective applications in various optoelectronic devices and flexible integrated systems.

Photo-Triggered Logic Circuits Assembled on Integrated Illuminants and Resonant Nanowires.

High-performance photo-triggered electronic devices have already become an abiding target of optoelectronics. Current results, involving high-sensitivity phototransistors with the enhancement of material properties or the modification of electrical field, need an independent external light-source system. Nevertheless, few research studies inform of circuits in which the logic channel can be directly light controlled by a fully integrated photogate. In this paper, nanowire-based photon-effect transistors (PETs) combined with organic light-emitting diode (OLED) gates, and the photo-triggered nanowire circuits (PTNCs) are exhibited. The nanowire channels are manifested as high-quality optical cavities coupled by reflective electrodes for forming standing wave resonance. With the function of resonance, the nanowire channel under the illumination of the OLED gate can reach a high on/off ratio of ∼107, and under the different interconnected configuration of OLED gates, the functions of PETs can separately be realized as P-type and N-type of CMOS-like transistors. Then, a PTNC inverter that includes two nanowire channels with the respective OLED gates is operated utilizing electrical input voltage and logic opposite output signal. NAND and NOR gates as PTNC have also been demonstrated and indicate their corresponding outstanding arithmetic logic operation. PTNCs can effectively represent an innovative step toward multipurpose photonic circuits as to programmable logic components and photo-triggered computing.

High Performance and Efficiency Resonant Photo-Effect-Transistor by Near-Field Nano-Strip-Controlled Organic Light Emitting Diode Gate.

Phototriggered devices have attracted attention due to their exceptional characteristics, advanced multifunctionalities and unprecedented applications in optoelectronic systems. Here, we report a pioneer structural device, a resonant photoeffect-transistor (RPET) with a functionalized nanowire (NW) charge transport channel, modulated by a near-field nanostrip organic light emitting diode (OLED) and controlled by a gate bias to realize exceptional photoelectric properties. The RPET presents high-quality nanowire channel characteristics due to tunable optical cavities manifesting strong standing wave resonance under controlled light emission. To enhance performance, methodical analyses were carried out to determine the effects of the structural design, electric field distribution and charge carrier generation on photoresponsivity when light traverses a single or multiple nanoslit masks. The developed RPET yields stable photocurrents in the 105 range and generates current on/off ratios upward of 106 under the influence of intense electromagnetic distribution, effectively lending itself to promising opportunities in fully integrated optoelectronic devices.

Conjugated Polymer Controlled Morphology and Charge Transport of Small-Molecule Organic Semiconductors.

In this study, we report an effective approach to tune the crystallization, microstructure and charge transport of solution-processed organic semiconductors by blending with a conjugated polymer additive poly(3-hexylthiophene) (P3HT). When 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) was used as a model semiconductor material to mix with different amount of P3HT, their intermolecular interactions led to distinctive TIPS pentacene film morphologies, including randomly-oriented crystal ribbons, elongated needles with enhanced long-range order, and grass-like curved microwires with interlinkages. Each type of morphology was found to further correlate to considerably different charge transport and device performance. As compared to pristine TIPS pentacene devices, bottom-gate, top-contact OTFTs with 2% in weight P3HT additive showed a 2-fold and 5-fold improvement of average field-effect mobility and performance consistency (defined as the ratio of average mobility to the standard deviation), respectively. The improvement in transistor electrical performance can be attributed to the combined effect of enhanced crystal orientation and uniformity, as well as increased areal coverage. This work can be applied beyond the particular example demonstrated in this study and to tune the charge transport of other small-molecule organic semiconductors in general.

Modifying Electrical and Magnetic Properties of Single-Walled Carbon Nanotubes by Decorating with Iron Oxide Nanoparticles.

In this work, we report a facile approach to modify the magnetic and electrical property of Hipco single-walled carbon nanotubes (SWCNTs) by attaching iron oxide nanoparticles (FeNPs). The Raman spectra of FeNP-SWCNTs revealed an apparent intensity reduction of metallic peaks in Radial breathing mode (RBM) region, which indicates the ratio change between the metallic and semiconducting component of SWCNTs after modification. Distinctive magnetic and electric resistance properties of FeNP-SWCNTs were found to be associated with the different shapes of FeNPs. The specific FeNP examples as showcased in this work can be applied to tune the electric and magnetic properties of other nanostructured materials in general and shed light on various electronic and magnetic applications.

Retracted Article: Wavelength modulation of ZnO nanowire based organic light-emitting diodes with ultraviolet electroluminescence.

Although organic light emitting diodes (OLEDs) can find important applications in display-related fields, it still remains a challenge to fabricate high-efficiency ultraviolet (UV) OLEDs with tunable wavelength. In this work, we demonstrate a facile method to adjust the electroluminescence (EL) peak from an inverted UV-OLED device that has zinc oxide nanowires (ZnO NWs) as an electron injection layer. The organic-inorganic interface between ZnO NWs and the 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ) emission layer employed in this work allows a reduction of the diffusion length of excitons, which further results in a hampered relaxation process of higher energy states as well as a blue shift of the EL spectrum. As a result, the emission peaks of the UV-OLED can be easily adjusted from 383 nm to 374 nm by tuning both the length of the ZnO NWs and the thickness of the TAZ emission layer. Our work reveals an important correlation between emission peaks and exciton diffusion, and presents a novel approach to fabricate high-performance UV-OLEDs with the capability of facilely modifying the emission wavelength.

Retraction: Wavelength modulation of ZnO nanowire based organic light-emitting diodes with ultraviolet electroluminescence.

[This retracts the article DOI: 10.1039/D0RA04058D.].

Polymer additive controlled morphology for high performance organic thin film transistors.

Solution-crystallizable small-molecule organic semiconductors, such as 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS pentacene), 5,11-bis(triethylgermylethynyl)anthradithiophene (diF-TEG-ADT), 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT), and N,N'-1H,1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN2), demonstrate various practical advantages including high mobility, air stability and solution processibility. In this article, we review various polymer additive based approaches to control the crystal morphology and the resultant charge transport of some bench-mark, high performance, solution crystallizable, small-molecule organic semiconductors. The polymer additives are discussed under the categories of non-conjugated polymers and conjugated polymers. The approaches and structure-performance correlations that we discussed here may be applied far beyond the examples shown in this review and have important implications for high performance organic semiconductors in general.

Layer-dependent anisotropic frictional behavior in two-dimensional monolayer hybrid perovskite/ITO layered heterojunctions.

Two-dimensional (2D) organic-inorganic hybrid perovskites, which possess outstanding optical and electrical properties, are promising semiconductor materials that have attracted significant interest in widespread applications. The frictional behavior of 2D perovskite materials with other transparent conductive materials, such as indium tin oxide (ITO), offers promising developments in optoelectronic devices. Therefore, the understanding of this frictional behavior is essential. Atomic force microscopy (AFM) is employed here to measure the frictional behavior between the (001) plane of the 2D organic-inorganic hybrid (C4H9NH3)2PbBr4 perovskite and the (111) plane of the ITO. The experimental analyses characterizing the nature of the friction in a single-crystalline heterojunction are reported. Based on the results of the analyses of interfaces between 2D monolayer perovskites and ITO, a strong anisotropy of friction is clearly demonstrated. The anisotropy of friction is observed as a four-fold symmetry with low a frictional coefficient, 0.035, in misaligned contacts, and, 0.015, in aligned contacts in the heterojunction configuration. In addition, atomistic simulations reveal underlying frictional mechanisms in the dynamical regimes. A new phenomenon discovered in the studies establishes that the measured frictional anisotropy surprisingly depends on the number of atomic layers in the 2D perovskite. The frictional anisotropy decreases significantly with the increase in the number of layers up to 16 layers, and then it becomes independent of the thickness. Our results are predicted to be of a general nature and should be applicable to other 2D hybrid perovskite heterojunction configurations, and thus, furthers the development of adaptive and stretchable optoelectronic nanodevices.