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...

The formation of nanoscale zinc oxide particles with an almost-monomodal size distribution synthesized by microwave heating of solutions of mononuclear zinc oximato or zinc acetylacetonato complexes in various alkoxyethanols is investigated. Transparent stable suspensions that contain these particles can be obtained from the zinc oximato precursor. Based on electron paramagnetic resonance (EPR) studies, a core/shell model with a finite surface shell thickness of 1.000 ± 0.025 nm is proposed for the ZnO nanoparticles. Field-effect transistor (FET) devices with these ZnO particles as the active semiconducting layer exhibited a charge carrier mobility of 0.045 cm2/(V s) and I on/off current ratios of ∼460.000, with a threshold voltage of 8.78 V.

No abstract

The suitability of amino acids and dipeptides as structure-directing agents for the deposition of coatings from aqueous solutions of zinc salts is discussed. According to a bio-inspired approach, the influence of these biomolecules was investigated with respect to the evolution of architectures based on zinc oxide and basic zinc salts. The small molecules were able to trigger the morphology of these materials ranging from grainlike to two-dimensional up to three-dimensional features. Besides morphological aspects, the structural characterization of these solids by means of electron and atomic force microscopies, photoelectron and infrared spectroscopies, and X-ray diffraction are discussed in order to extract the function of the biomolecules with regard to the formation of the inorganic phases.