Since the development of the electronic transistor 60 years ago its technical utilization has revolutionized modern society. Consequent miniaturization was the key to this development. The challenge to develop flat printable electronics based on inorganic materials could give this area further input. It could be the basis for flexible displays or electronic paper when the active material is processable from solution, shows very good adherence to flexible substrates and excellent physical performance.[1] To meet these challenges any material considered requires a tuned set of functional properties. In general inorganic semiconductors are in advantage over organic materials as far as their physical performance is concerned. However, often processing and adherence to substrates is a problem with inorganic semiconductors. ZnO is available in various morphologies as transparent oxide, is non toxic, inexpensive and has shown promising physical semiconductor properties. [2][3][4] For solution processedZnO field-effect transistor (FET) devices, the highest electron mobility values are currently 1.65 cm 2 V À1 s À1 , however obtainable only after calcinations at temperatures >300 8C.[5] So far, despite promising physical performance parameters, neither synthesis conditions, nor processing techniques are yet compatible with existing printing technologies envisioned for flexible printing of ZnO semiconductors on polymer substrate basis. Currently the utmost challenge in the field is to gain a most complete understanding of the interplay between the parameters synthesis, processing and semiconductor performance for future development of printable electronic devices based on inorganic semiconductors such as ZnO. Despite a couple of recent reports on the deposition of zinc oxide thin layers in FET devices, processing from solution and conversion into the active FET channel electrode under fairly mild conditions is a great challenge. Chemical bath deposition techniques [6,7] and sol-gel processes were mainly investigated in this regard. [5,[8][9][10] However, both techniques typically require either high processing temperatures (above 300 8C) or long reaction times and are thus inappropriate for printing applications on flexible polymer based substrates under state of the art printing conditions. Processing temperatures well below 200 8C are the goal for the formation of semiconducting inorganic thin films onto such substrates. The application of soft processes like spin or dip coating or any kind of printing or stamping rely on the formation and adherence of such thin films on flexible substrates. Herein we report our investigations on the formation, characterization, low temperature processing and printing behavior of a molecular precursor and its conversion to unifom ZnO thin films and promising electronic performance of such films in an FET device.Our process starts from a modified synthesis of the ZnO single source precursor bis [2-(methoxyimino)propanoato]zinc 1 [11,12] (Scheme 1) which we developed for depositing thin tr...

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What took so long? An ex situ investigation of an iron–aluminum nanocatalyst that is active in the water‐assisted growth of “super‐long” carbon nanotubes (CNTs) with different techniques (HRSTEM, EELS, XPS, GIXRD) reveals for the first time its bimetallic nature. Besides metallic aluminum and iron, mixed oxides, hydroxides, and aluminum oxycarbides play a role in the CNT growth process.

A novel molecular approach to the synthesis of polycrystalline Cu-doped ZnO rod-like nanostructures with variable concentrations of introduced copper ions in ZnO host matrix is presented. Spectroscopic (PLS, variable temperature XRD, XPS, ELNES, HERFD) and microscopic (HRTEM) analysis methods reveal the +II oxidation state of the lattice incorporated Cu ions. Photoluminescence spectra show a systematic narrowing (tuning) of the band gap depending on the amount of Cu(II) doping. The advantage of the template assembly of doped ZnO nanorods is that it offers general access to doped oxide structures under moderate thermal conditions. The doping content of the host structure can be individually tuned by the stoichiometric ratio of the molecular precursor complex of the host metal oxide and the molecular precursor complex of the dopant, Di-aquo-bis[2-(methoxyimino)-propanoato]zinc(II) 1 and -copper(II) 2. Moreover, these keto-dioximato complexes are accessible for a number of transition metal and lanthanide elements, thus allowing this synthetic approach to be expanded into a variety of doped 1D metal oxide structures.

Solution-processed metal oxide semiconductors are of high interest for the preparation of high-mobility transparent metal oxide (TMO) semiconductor thin films and thin film transistors (TFTs). It has been shown that the charge transport properties of indium–zinc oxide (IZO) thin films from molecular precursor solutions depend strongly on the preparation conditions, in particular on the precursor conversion temperature T pc and, to some surprise, also on the concentration of the precursor solution. Therefore, the chemical and the electronic structure of solution-processed IZO thin films have been studied in detail with X-ray photoelectron spectroscopy (XPS) under systematic variation of T pc and the concentration of the precursor solution. A distinct spectral feature is observed in the valence band spectra close to the Fermi level at E B = 0.45 eV binding energy which correlates with the trends in the sheet resistivity, the field effect mobility μFE, and the optical gap E g opt from four-point-probe (4PP), TFT, and UV–vis measurements, respectively. A comprehensive model of the interrelation between the conditions during solution-processing, the chemical and electronic structure, and the charge transport properties is developed.