Traditional fluorescence-based tags, used for anticounterfeiting, rely on primitive pattern matching and visual identification; additional covert security features such as fluorescent lifetime or pattern masking are advantageous if fraud is to be deterred. Herein, we present an electrohydrodynamically printed unicolour multi-fluorescent-lifetime security tag system composed of lifetime-tunable lead-halide perovskite nanocrystals that can be deciphered with both existing time-correlated single-photon counting fluorescence-lifetime imaging microscopy and a novel time-of-flight prototype. We find that unicolour or matching emission wavelength materials can be prepared through cation-engineering with the partial substitution of formamidinium for ethylenediammonium to generate “hollow” formamidinium lead bromide perovskite nanocrystals; these materials can be successfully printed into fluorescence-lifetime-encoded-quick-read tags that are protected from conventional readers. Furthermore, we also demonstrate that a portable, cost-effective time-of-flight fluorescence-lifetime imaging prototype can also decipher these codes. A single comprehensive approach combining these innovations may be eventually deployed to protect both producers and consumers.

stability when compared to their counterparts. [4] Currently existing technologies for commercial applications of TFTs use vacuum-based deposition methods and photolithographic patterning of the layers to ensure a high manufacturing yield.Due to the availability of inexpensive precursors, ease of fabrication, and applicability for large-area processing, solutionprocessed methods may offer low-cost routes for the manufacturing of oxidebased TFTs. [5] Specifically, printing offers an advantage by eliminating the necessity of photolithographic patterning of the deposited layers. However, there are still several challenges before the realization of flexible electronics based on printed oxides, and one of them is the requirement of a hightemperature post deposition annealing (PDA) of the printed layers. [6] To reduce the PDA temperature of the solution-processed layers, several methods such as deep ultraviolet (DUV) annealing, [7][8][9] flash lamp annealing, [10,11] microwave annealing, [12] and solution combustion synthesis [13][14][15][16] have been proposed for semiconductor, conductor, and dielectric layers. DUV annealing (annealing method in this study) is based on the absorption of the deep UV light (λ < 260 nm) by the precursors used in the solution-processed deposition resulting in their decomposition into active oxide layers. DUV has been demonstrated to be applicable not only to oxide dielectrics but also to the semiconductors such as indium oxide, IGZO, and indium zinc oxide. [8] As a major component of the TFT, the dielectric layer is crucial for achieving high-performance devices. The effective polarization of charges in the dielectric under the applied gate bias directly affects the amount of charges accumulated/ depleted in the channel material, which in turn indicates the switching performance of the transistor. Up to now, the majority of low-temperature solution-processed dielectric layers have been reported using spin coating methods, aiming at uniform and pinhole-free layers. [17] Several binary oxide dielectrics with high dielectric constants (high-κ) such as AlO x , YO x , HfO x , and ZrO x have been investigated for their use in oxide TFTs, and the devices with higher mobilities and lower threshold voltages rather than the devices employing SiO 2 insulators Recent developments in inkjet printing have proven it a viable method for low-cost and large-area coating of oxide materials. The main drawback of this method is the common requirement of a post-deposition annealing (PDA) of the printed layers at relatively high temperatures (T > 200 °C). This sets a requirement for the substrate to have high glass transition temperature (T g ). Toreduce the PDA temperature, deep-ultraviolet (DUV) annealing is proposed as an effective method. In this study, yttrium aluminum oxide (YAlO x ) dielectrics are realized for application in flexible electronic devices via inkjet printing and DUV annealing at a temperature of 150 °C. The effect of the Y concentration on the electrical properties of the dielectrics is i...

Indium tin oxide (ITO) is a transparent conducting material that is widely used in devices where high transparency of the electrodes is required, such as flat panel and liquid crystal displays, touch panels, smart windows, and many others. ITO layers are deposited on a large scale by magnetron sputtering and then structured by lithography to define desired patterns of transparent electrodes. Here, a method for direct printing of transparent conductive patterns from ITO nanoparticle ink is communicated. The method combines inkjet printing with fast flash lamp annealing whereby the main novelty is to use an additional layer of a colored organic dye onto printed ITO to increase light absorption. The dye coating is instantly heated together with the underlying ITO layer by a light pulse, leading to an instant rise of the surface temperature, which is translated into improved optoelectronic properties of the ITO layers. Inkjet‐printed ITO patterns processed with the dye‐assisted flash lamp annealing exhibit a transmittance of up to 88% at 550 nm and resistivity of 3.1 × 10−3 Ω cm. Transparent touch‐sensing trackpad and capacitive touch sensors are demonstrated based on the printed ITO patterns, which can be utilized in transparent security systems and other transparent Internet‐of‐Things devices.

Traditional fluorescence-based tags, used for anticounterfeiting, rely on primitive pattern matching and visual identification; additional covert security features such as fluorescent lifetime or pattern masking are advantageous if fraud is to be deterred. Herein, we present an electrohydrodynamically printed unicolour multi-fluorescent-lifetime security tag system composed of lifetime-tunable lead-halide perovskite nanocrystals that can be deciphered with both existing time-correlated single-photon counting fluorescence-lifetime imaging microscopy and a novel time-of-flight prototype. We find that unicolour or matching emission wavelength materials can be prepared through cation-engineering with the partial substitution of formamidinium for ethylenediammonium to generate "hollow" formamidinium lead bromide perovskite nanocrystals; these materials can be successfully printed into fluorescence-lifetime-encoded-quick-read tags that are protected from conventional readers. Furthermore, we also demonstrate that a portable, cost-effective time-of-flight fluorescencelifetime imaging prototype can also decipher these codes. A single comprehensive approach combining these innovations may be eventually deployed to protect both producers and consumers.

polar liquid layer on the substrate which serves as a transfer mechanism; therefore they are still costly for high volume manufacturing of transparent electrodes in lowcost applications. Other options, such as randomly distributed metal nanofibers [7] or nanowire networks [8,9] allow no control of the location and pattern of the wires as they are always randomly distributed on the substrate. On a micrometer scale of creating silver wires, inkjet [10] and gravure printing [11,12] are low-cost additive methods used for printed electronics, yet with resolutions often in the range much larger than 10 µm. [13] They are not suitable for applications where sub-micrometer or even sub-100 nm resolutions (e.g., for subwavelength optics) are needed. In order to shrink dimensions without using traditional lithography, the patterning of nanoparticles by self-assembly on pre-patterned substrates is a solution. It has been tested for the generation of dense arrays of 50-80 nm silica particles in V-grooves. [14] Capillary assisted particle assembly (CAPA) is used for the parallel assembly of sub-micrometer particles into hexagonal arrangements by convective or capillary effects. [15,16] However, nanoparticle inks have polydisperse distribution of particle sizes (here between 20 and 80 nm) and therefore typically do not self-assemble but rather form a loose agglomeration, which is merged into a 3D cluster by post-processing (e.g., sintering).The objective of the present paper is to provide a novel method for reducing the width of structures generated by ink deposition on pre-patterned substrates. We aim to achieve resolutions which are not only much smaller than the resolution of the applied additive process, but also smaller than the width of the pre-patterned structures. Pre-patterning the substrates with specific sub-micrometer topography can be done by straightforward replication techniques such as thermal or UV-assisted NIL which can then be covered either locally (e.g., by inkjet printing) or on an entire substrate (by spincoating). This enables the generation of fine structures in the micrometer range down to subwavelength range at low cost and high throughput, and thus satisfies the demand for a technology being less expensive than currently known lithographic processes. In the process proposed here, we use this approach to fill V-groove shaped substrates with silver nanoparticle-based inks, typically with average 50 nm particles dispersed in a suitable solvent. [17] The nature of the V-groove substrates with inclined sidewalls and Λ-ridges between adjacent grooves separates individual lines Here, the fabrication of sub-200 nm metal wires from commercial silver inks with 50 nm particle size, 100 times narrower than with typical low-resolution ink-jet and screen printing in flexible electronics, is demonstrated. Using a combination of spincoating on prepatterned polymer substrates and flash lamp annealing, nanoparticles merge to wires featuring good electrical conductivity. With this method less than 150 nm thin wires can ...