Colloidal quantum dots (QDs) stand at the forefront of a variety of photonic applications given their narrow spectral bandwidth and near-unity luminescence e ciency. Integrating desired forms of QD lms into photonic systems without compromising their optical or transport characteristics is the key to bridging the gap between expectations and outcomes. Here, we devise a dual-ligand passivation system comprising photocrosslinkable ligands and dispersing ligands to enable QDs to be universally compatible with solution-based patterning techniques. The successful control on the structure of both ligands allows multiscale, direct patterning of the dual-ligand QDs on various substrates via commercialized photolithography (i-line) or inkjet printing systems without compromising the optical properties of QDs or the optoelectronic performances of the devices implementing them. Our approach offers a versatile way of creating various structures of luminescent QDs in a cost-effective and non-destructive manner, and thus enables the implementation of QDs in a range of photonic applications. MainColloidal quantum dots (QDs) are promising materials for use in next-generation light sources due to their wide-ranging bandgap tunability, narrow spectral bandwidths, and near-unity luminescence quantum yields (QY) [1][2][3][4][5] . Together with the capability of cost-effective solution processing, QDs have become the key light-emissive materials for information displays 3,5−7 . The patterned QD down-conversion layer on blue light-emitting diodes (LEDs) renders high-color reproduction and ultra-high image quality in full-color displays 8,9 . Likewise, a laterally patterned array consisting of red, green, and blue (RGB) QD-LEDs, in which QDs convert electrically pumped charge carriers into photons, allows for excellent color gamut and brightness as well as light-weight, thin, and exible form factors [10][11][12][13] , which are suited for wearable neareye displays for virtual reality (VR) and augmented reality (AR) devices. For these "mixed-reality" applications, the QD deposition process should enable the patterning of RGB QDs (or RG QDs along with the bank) into a few micrometer sub-pixels over a large area with high-precision and high-delity 14,15 . At the same time, the process should not disrupt the optical and transport characteristics of QDs and adjacent functional layers. Moreover, from a practical standpoint, it poses great bene t if one can use equipment that are already deployed in display device manufacturing steps for the patterning process.

Printing solid-state elastic conductors into self-supporting three-dimensional (3D) geometries promises the design diversity of soft electronics, enabling complex, multifunctional, and tailored human-machine interfaces. However, the di culties in manipulating their rheological characteristics have only allowed for layerwise deposition. Here, we report omnidirectional printing of elastic conductors enabled by emulsifying elastomer composites with immiscible, nonvolatile solvents. The strategy simultaneously achieves superior viscoelastic properties that provide the structural integrity of printed features, and pseudoplastic and lubrication behaviours that allow great printing stability. Freestanding, lamentary, and out-of-plane 3D geometries of intrinsically stretchable conductors are directly written, achieving a minimum feature size <100 μm and excellent stretchability >150%. Particularly, the evaporation of the continuous phase in the emulsion results in microstructured, surface-localized conductive networks, signi cantly improving their electrical conductivity. To illustrate the feasibility of our approach, we demonstrate skin-mountable electronics that visualize temperature on a matrix-type stretchable display based on omnidirectionally printed elastic interconnects. Full TextSkin electronics augment the capability of shareable signals from personal and metabolic activities over communication networks by blurring the physical discontinuity between electronic devices and human skin [1][2][3][4] . With their unique mechanical characteristics, such as lightweight design, softness, and stretchability, skin electronics can be functionalized on various body parts 5,6 and even brains 7 and hearts 8 in the forms of biosensors, processors, and displays. For high-delity operation under these challenging circumstances, the design of skin electronics needs to be tailored elaborately to individuals 9,10 . However, traditional mask-based lithography primarily optimized for the mass production of standardized, uniform electronics cannot effectively deal with the morphological diversity of the human bodies. Moreover, existing manufacturing processes still lack strategies to implement threedimensional (3D) structures with soft functional materials such as vertical interconnect accesses (VIAs) and multilayer circuitries that are crucial to the realization of high-performance, multifunctional applications.Printing electrical wirings into 3D structures could be a promising solution for maximizing the customizability of skin electronics and achieving circuit complexity. However, most conventional 3D printing processes still deposit one layer at a time, which is unsuitable for complex, lamentary, and omnidirectional wirings (including a z-directional component). Alternatively, viscoelastic inks that simultaneously exhibit high quasi-static stiffness and strong shear-thinning behaviour can immediately solidify after extrusion from a nozzle-based printhead, allowing direct writing of self-supporting 3D structures [11][12][13][14][15...

Recently there has been growing interest in avalanche multiplication in two-dimensional (2D) materials and device applications such as avalanche photodetectors and transistors. Previous studies have mainly utilized unipolar semiconductors as the active material and focused on developing high-performance devices. However, fundamental analysis of the multiplication process, particularly in ambipolar materials, is required to establish high-performance electronic devices and emerging architectures. Although ambipolar 2D materials have the advantage of facile carrier-type tuning through electrostatic gating, simultaneously allowing both carrier types in a single channel poses an inherent difficulty in analyzing their individual contributions to avalanche multiplication. In ambipolar field-effect transistors (FETs), two phenomena of ambipolar transport and avalanche multiplication can occur, and both exhibit secondary rise of output current at high lateral voltage. We distinguished these two competing phenomena using the method of channel length modulation and successfully analyzed the properties of electron- and hole-initiated multiplication in ambipolar WSe2 FETs. Our study provides a simple and robust method to examine carrier multiplication in ambipolar materials and will foster the development of high-performance atomically thin electronic devices utilizing avalanche multiplication.

Going beyond an improved colour gamut, an asymmetric colour contrast, which depends on the viewing direction, and its ability to readily deliver information could create opportunities for a wide range of applications, such as next-generation optical switches, colour displays, and security features in anti-counterfeiting devices. Here, we propose a simple Fabry–Perot etalon architecture capable of generating viewing-direction-sensitive colour contrasts and encrypting pre-inscribed information upon immersion in particular solvents (optical camouflage). Based on the experimental verification of the theoretical modelling, we have discovered a completely new and exotic optical phenomenon involving a tuneable colour switch for viewing-direction-dependent information delivery, which we define as asymmetric optical camouflage.