The main results achieved are:
• R1: The construction and testing of the three demonstrators: smart bottle, car window control and car seat sensor array that were presented in Semicon 2017
• R2: Lab-scale sputtered indium-free zinc-tin oxide (ZTO) thin-film transistors (TFTs) fabricated on flexible PEN foil with maximum processing temperature of 180 °C having comparable performance to state-of-the-art indium-gaIlium-zinc oxide (IGZO) TFTs: µFE≈5 cm2/Vs, Von≈0 V, On/Off ratio >106, S≈0.2 V/dec. Under negative bias illumination stress threshold voltage only shifts -1 V (λ=420 nm, VGS=-4 V, during 1 h), being the shift fully recoverable after ≈10 min.
• R3: Design, simulation, layout extraction, fabrication and characterization of an integrated circuit for the readout of fill-level and temperature sensing in smart bottles, entirely based on oxide TFTs. The system has a significant complexity (>180 transistors, divided in analogue and digital blocks), showing the potential of oxide electronics to go well beyond the conventional switching and current driver elements of displays.
• R4: Completion of three fully roll-to-roll process for thin film transistors and circuits combining printing, evaporation, lift-off, sputtering and ALD fabrication steps at three different partners. Good performance has not been achieved due to the small number of trials not being enough to eliminate all the problems in substrate scratching, layer cracking as well as mechanical and thermal stress. However, the overall process compatibility has been demonstrated and new process steps have been verified in the patterning of the layers.
• R5: To increase the number of printed layers, usage of silver nanoparticle ink for S/D contacts of oxide TFT has been developed based on interface modification with PEI.
• R6: A printable all-organic proton battery has been presented. The battery is completely devoid from metals and can, in principle, be disposed of by combustion.
The objectives of the project are evaluated as follows:
1. Industrially relevant level of performance met, not fully the objective (see R2 above).
2. Partially met. TFTs integrating ALD-Al2O3 (Picosun) and sputtered-ZTO (Polyteknik) were successfully fabricated on 4” PEN substrates with maximum temperature of 150 °C. After multiple runs between UNINOVA, Picosun and Polyteknik for process tuning, performance metrics were µFE≈2 cm2/Vs, Von≈0 V, On/Off ratio >106, S≈0.6 V/dec. Then, TFTs and circuits have been fabricated using R2R processing for all the steps. Three processing rounds have been completed. Each multi-site processing trial has taken several months and has faced unforeseen challenges (See R4 above)
3. Met. Pressure sensors technology, mostly based on interdigitated metal electrodes with several functional layers on top have been scaled up to R2R processes.
4. Met by replacement solutions, namely TFT based temperature sensing circuits.
5. The battery objectives have been partially met. The presented battery relies on proton cycling and provides capacities in the range of 100-120 mAh/g active material. A printable all-organic battery and batteries with solid separators have thus been developed within the project and the capacity is close to the one specified. The voltage requirements have proven difficult to meet due to difficulties in altering the redox potential of individual components through chemical modifications without compromising material stability and thorough theoretical and experimental studies on has been undertaken to solve this issue.
6. Exceeded. The project has demonstrated all the R2R processing steps for a substrate width of 30 cm.
7. Not met. A flexible autonomous system was implemented using sputtering as a S2S process for the smart bottle demonstrator, using lab-scale processes. However, yield and uniformity issues of the lab-scale processing tools have prevented the whole system based on oxide electronics to work although all the modules have separately been confirmed to be functional. The R2R processing has fabricated TFTs and part of the needed circuit blocks of autonomous systems but only few TFTs have been functional due to processing challenges that would need more focus such as registration errors, scratching of the substrate, non-perfect lift-off, thermal and mechanical stresses etc.
8. Met. A demonstrator was presented at Semicon Europa in November 2017.
9. Not met. The pressure sensor array was implemented on textile and the silver coatings showed good conductance. However, after insulator coating processing, some cracks appear on the silver layers and the silver conductivity was not suitable for the application. On the other hand, a functional proof of concept prototype based on a smaller area has been developed.
10. Met with the exception of the pressure sensing that was dropped in 2016 as reported earlier. A demonstrator was presented at Semicon Europa in November 2017.
