This Small Business Innovation Research (SBIR) Phase I project aims to develop semiconductor and dielectric inks for thin-film transistor devices to drive Active Matrix organic light-emitting diode (AMOLED) displays. The approach is to employ novel aqueous-based inorganic precursors with low energy barriers to condensation, which will enable the solution deposition of high-quality electronic films that can be cost-effectively scaled to large substrates with uniformity. This project will combine inorganic ink design with flashlamp process for printed electronics to fabricate transistors. It is expected to meet the challenging performance requirements for AMOLED displays on glass with a direct path to low temperature flexible substrates. By tuning the precursor formulation for optimum absorbance and adjusting the flashlamp pulse conditions, the energy required to complete dehydration will be deposited precisely in the film with minimal thermal impact on the substrate.
The broader/commercial impact of this project will be the potential to provide semiconductor and dielectric inks to enable more energy efficient AMOLED displays. AMOLED is the fastest growing segment in display industry. The potential served market for related advanced transistor materials will be about $100 million. The materials and low temperature processes developed in this project will also lay the foundation for much broader applications in inorganic printed electronics and large-area dielectric/optical coatings.
Inpria is enabling disruptive electronics manufacturing methods through solution deposited inks made inexpensively from abundant, environmentally benign raw materials. Our core materials technology provides the unique ability to make extremely high-quality metal oxide films from aqueous solutions thereby improving device performance while significantly reducing deposition cost. Together with partners, we have shown that our line of semiconductor and dielectric electronic inks has the potential to be used as a high-performance replacement for amorphous silicon in LCD display backplanes. The objective of the research reported here was to combine recent progress in flashlamp processing for printed electronics with our unique inks to reach the challenging transistor performance requirements for advanced displays on glass. This also has direct application to lower temperatures and flexible substrates (for display and other flexible electronics) as well as elimination of costly traditional patterning steps. AMOLED is the display industry’s fastest growing segment but is currently constrained to small substrates – the technology developed here provides a path to large and/or flexible substrates. As a result of this project, we made a number of commercially important findings, and draw the following conclusions: Flash lamp annealing of indium gallium zinc oxide (IGZO) semiconductor films significantly improved performance of low temperature (275ºC) annealed TFT devices. Improvement in baseline (350ºC) performance was not observed. A similar trend in improved performance was observed using excimer laser annealing. Flash lamp annealing was ineffective in improving dehydration of our aqueous gate insulator precursors. Alternate chemical means were conceived and demonstrated to improve dehydration of specific gate insulator films. This provided a route solid device performance at the required thickness with low capacitance density.
