In order to achieve high performance levels in a complementary electronic system which consists of electron transporting (n-type) and hole transporting (p-type) semiconductors the most effective way is to optimise the respective semiconducting materials separately in terms of performance and processability. We started working with n-type materials namely metal oxides such as zinc oxide (ZnO) or indium oxide (In2O3) which are processed from solution. Various structure configurations were fabricated on silicon and glass substrates using single and mixed multilayer architectures (heterostructures) of these semiconducting materials and analysed in regard to the use of different annealing temperatures ranging from 200 to 600 °C. After establishing an optimised layer system reaching the targeted performance levels set in the beginning of the project we developed a novel annealing technique (photonic curing) using high power xenon flash light to dry and anneal the solution-processed metal oxide films and thus replaced the conventional thermal annealing using temperatures beyond 200 °C accompanied with a significant saving of the processing time (18 seconds vs. 1 hour). Our studies revealed comparable performances of the photonically to the thermally annealed devices. Moreover, this approach allowed us to deposit semiconducting metal oxide films from solution on low-temperature substrate materials such as plastics which is a ground-breaking outcome of this project.
In a second step we started working on optimizing and improving the electronic properties of p-type semiconductors namely organic materials such as small molecules and/or polymers. Again, different architectures and material systems were analysed using maximum temperatures of 150 °C in combination with chemical doping techniques to tune the electronic properties resulting in performance levels close to those reached with the photonically annealed n-type metal oxides. These important findings finally build the cornerstone for the key target to fabricate high performing electronic devices and circuits on inexpensive, low-temperature substrates such as plastics.
The main findings from this project have been published and have been presented at an array of scientific meetings
K. Tetzner, I. Isakov, A. Regoutz, D. J. Payne and T. D. Anthopoulos, The impact of post-deposition annealing on the performance of solution-processed single layer In2O3 and isotype In2O3/ZnO heterojunction transistors, J. Mater. Chem. C, 2017, 5, 59.
S. Dellis, I. Isakov, N. Kalfagiannis, K. Tetzner, T. D. Anthopoulos and D. C. Koutsogeorgis, Rapid laser-induced photochemical conversion of sol–gel precursors to In2O3 layers and their application in thin-film transistors, J. Mater. Chem. C, 2017, 5, 3673.
K. Tetzner, Y.-H. Lin, A. Regoutz, A. Seitkhan, D. J. Payne and T. D. Anthopoulos, Sub-second photonic processing of solution-deposited single layer and heterojunction metal oxide thin-film transistors using a high-power xenon flash lamp, J. Mater. Chem. C, 2017.
K. Tetzner, H. Faber, T. D. Anthopoulos, Understanding the structure-property relationship in high-performance solution-processed bilayer metal oxide transistors, 13th International Conference on Nanosciences & Nanotechnologies (NN16), 5-8 July 2016, Thessaloniki, Greece.
K. Tetzner, Y.-H. Lin, T. D. Anthopoulos, Rapid fabrication of solution-processed metal oxide transistors via photonic processing at room temperature, Innovations in Large-Area Electronics Conference, 31 January - 1 February 2017, Wellcome Genome Campus Conference Centre, Hinxton, UK.
K. Tetzner, Y.-H. Lin, A. Regoutz, T. D. Anthopoulos, Photonic curing of solution-processed metal oxide semiconductors for the rapid fabrication of low-voltage thin-film transistor devices, European Materials Research Society Conference, 22-26 May 2017, Strasbourg, France.
K. Tetzner, Y.-H. Lin, A. Regoutz, A. Seitkhan, D. J. Payne, T. D. Anthopoulos, Sub-second photonic curing of solution-processed metal oxide thin-film transistors via high-power xenon flash treatment, CPE Researchers’ Symposium at Imperial College London, 26 June 2017, London, UK.
K. Tetzner, Y.-H. Lin, T. D. Anthopoulos, Large-area photonic-annealing for the rapid fabrication of high-performance solution-processed metal oxide transistors, 14th International Conference on Nanosciences & Nanotechnologies (NN17), 4-7 July 2016, Thessaloniki, Greece.
