technology because of its higher brightness, lower power consumption, and faster response than OLED and LCD technologies. [1-5] They are expected to be suited for many applications in the brightnesssensitive or power-sensitive environments such as wearable devices, optogenetics, outdoor displays, and AR/VR. [6-13] Despite these attractive advantages, fabricating high-resolution micro-LED displays is proven to be very challenging because accurately assembling millions of micro-LEDs onto a driving circuit requires complicated transfer and bonding process. [3,14] A scalable active-driven micro-LED display device is primarily composed of two major parts: a micro-LED array, and a driver backplane. [14-20] In order to generate any display pattern, the micro-LED array must be electrically connected to the pads on the driver backplane. This is most commonly achieved by flip-chip bonding technologies such as bump bonding and anisotropic conductive film (ACF) bonding, [13] whereas in some cases it can be done using via filling or metal wiring technology. [3,4,21] The latter technology is not preferred, because for high-resolution display, both metal wires and vias occupy extra space. In the course of bonding, the small chip size may incur serious registration/alignment errors, resulting in forming display defects. Therefore, the fabrication of a micro-LED display device involves two challenging processes: i) assembling millions of micro-LED chips in a fast, accurate, and low-cost manner, and ii) reliably bonding the micro-LEDs onto the driver circuit with minimized displacement. Micro-LED arrays can be made in a monolithic manner, without using tedious pick-and-place technology. [12] In a monolithic approach, an array of micropixels is formed simultaneously on the same native substrate using only a lithography process, and all these pixels on the same substrate are then integrated onto a driver backplane via one-time flip-chip bonding. Optionally, the sapphire can be taken off by laser liftoff (LLO), [21,22] in order to suppress the optical crosstalk and beam divergence induced by the thick substrate. [23,24] Flip-chip bonding is a proven technology which is fast and compatible with wafer-level bonding. Furthermore, it can improve the light-emitting efficiency because of less light absorption caused The development of micro-sized light emitting diode (LED) displays has driven the research of micro-LED mass-transfer technology. To date, various transfer technologies are proposed, but ample room for improvements in the transfer yield and transfer accuracy still remains. Furthermore, whether these techniques are suited for the subsequent bonding process is not well investigated, which is essential for achieving a good electric connection between micro-LEDs and driver electronics. Here a systematical solution, termed as "tape-assisted laser transfer," which is not only suited for high-yield micro-LED transfer but also well compatible with subsequent bonding process, is developed. Using a low-cost adhesive tape as the support s...

Large-area, programmable assembly of diverse micro-objects onto arbitrary substrates is a fundamental yet challenging task. Herein a simple wafer-level micro-assembly technique based on the light-triggered change in both surface topography and interfacial adhesion of a soft photo-sensitive polymer is proposed. In particular, the light-regulated polymer growth creates locally indented and elevated zones on the stamp surface. The light-mediated adhesion reduction, on the other hand, facilitates the inks to be released from the polymer. The interplay of these two effects makes it feasible for the programmable assembly of ultra-small components onto various substrates coated with supplementary adhesive layers. The fidelity of this technique is validated by assembling diverse materials and functional devices, with the printing size up to 4-inch. This work provides a rational strategy for large-scale and programmable assembly of diverse delicate micro-objects, bypassing the common issues of some existing techniques such as poor transfer uniformity, small printing area, and high cost.

In this work, we performed a systematic study of the physical properties of amorphous Indium–Gallium–Zinc Oxide (a-IGZO) films prepared under various deposition pressures, O2/(Ar+O2) flow ratios, and annealing temperatures. X-ray reflectivity (XRR) and microwave photoconductivity decay (μ-PCD) measurements were conducted to evaluate the quality of a-IGZO films. The results showed that the process conditions have a substantial impact on the film densities and defect states, which in turn affect the performance of the final thin-film transistors (TFT) device. By optimizing the IGZO film deposition conditions, high-performance TFT was able to be demonstrated, with a saturation mobility of 8.4 cm2/Vs, a threshold voltage of 0.9 V, and a subthreshold swing of 0.16 V/dec.

Inorganic metal halide perovskite quantum dots (QDs) have emerged as a new class of solution-processable semiconductor materials for the next-generation display. However, such QDs commonly suffer from surface defects, resulting...

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As an important source of new drug molecules, secondary metabolites (SMs) produced by microorganisms possess important biological activities, such as antibacterial, anti-inflammatory, and hypoglycemic effects. However, the true potential of microbial synthesis of SMs has not been fully elucidated as the SM gene clusters remain silent under laboratory culture conditions. Herein, we evaluated the inhibitory effect of Staphylococcus aureus by co-culture of Eurotium amstelodami and three Bacillus species, including Bacillus licheniformis, Bacillus subtilis, and Bacillus amyloliquefaciens. In addition, a non-target approach based on ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOF-MS) was used to detect differences in extracellular and intracellular metabolites. Notably, the co-culture of E. amstelodami and Bacillus spices significantly improved the inhibitory effect against S. aureus, with the combination of E. amstelodami and B. licheniformis showing best performance. Metabolomics data further revealed that the abundant SMs, such as Nummularine B, Lucidenic acid E2, Elatoside G, Aspergillic acid, 4-Hydroxycyclohexylcarboxylic acid, Copaene, and Pipecolic acid were significantly enhanced in co-culture. Intracellularly, the differential metabolites were involved in the metabolism of amino acids, nucleic acids, and glycerophospholipid. Overall, this work demonstrates that the co-culture strategy is beneficial for inducing biosynthesis of active metabolites in E. amstelodami and B. licheniformis.

Nanocrystal (NC) CuInSe2 thin-film transistors (TFTs), consisting of nontoxic and relatively abundant elements, have great potential in environment-friendly and low-cost electronic devices. However, the high-performance CuInSe2 NC TFTs reported so far utilize toxic compounds, such as CdSe and hydrazine, which often require tedious and complex procedures. TFTs using directly synthesized CuInSe2 NCs as channel layers exhibit promising device performances but are still not comparable to the counterparts of cadmium and lead chalcogenide-based NCs. In this work, an efficient solution-based colloidal synthesis and ligand-exchange process have been developed to effectively remove bulky surfactant ligands from CuInSe2 NCs and produce unique inorganically connected NCs through metal-sulfide bonding using simple metal-free chalcogenide compounds. Such inorganically connected CuInSe2 NC thin films, combined with surface treatment, substantially affect charge transport through trap states and tunneling transport mechanism. The carriers tunneling through the barrier between neighboring NCs with much shorter interparticle distances significantly enhance electronic coupling and improve the electrical transport properties. CuInSe2 NC TFT exhibits the electrical performance with a mobility of 9.6 cm2/(V s), on/off current ratio over 104, and negligible hysteresis at low operating voltages, comparable to those for state-of-the-art II–VI- and IV–VI-type NC TFTs. As a proof of concept, the CuInSe2 NC TFTs are used as building blocks of integrated inverters to demonstrate their promise for low process temperature-fabricated NC circuits.

We report the featured gated field electron emission devices of Si nano-tips with individually integrated Si nano-channels and the interpretation of the related physics. A rational procedure was developed to fabricate the uniform integrated devices. The electrical and thermal conduction tests demonstrated that the Si nano-channel can limit both the current and heat flows. The integrated devices showed the specialties of self-enhancement and self-regulation. The heat resistance results in the heat accumulation at the tip-apex, inducing the thermally enhanced field electron emission. The self-regulated effect of the electrical resistance is benefit for impeding the current overloading and prevents the emitters from a catastrophic breakdown. The nano-channel-integrated Si nano-tip array exhibited emission current density up to 24.9 mA/cm2 at a gate voltage of 94 V, much higher than that of the Si nano-tip array without an integrated nano-channel.