Candidate: Jonathan Atkinson
Title: Silver Nanowire Networks in Electrochromic Devices
Date: December 3, 2018
Time: 3:00 PM
Place: QNC 1501
Supervisor(s): Goldthorpe, Irene
Abstract:
Window coatings increase energy efficiency in a building by reducing heat loss. Switchable electrochromic windows can improve efficiencies further by permitting solar heat, which occurs at near infrared wavelengths, to enter a building during the Winter but not in the Summer. However, the transparent electrodes used in electrochromic windows, typically metal oxides such as indium tin oxide (ITO) or fluorine doped tin oxide (FTO), have only moderate transparencies in the near infrared region and thus reduce the solar heat that could otherwise help heat a building in winter.
In this talk, I will show that silver nanowire networks are a potential replacement material for the transparent electrode in electrochromic smart windows. Silver nanowire networks are more than 90% transparent in the near infrared region compared to 40% for metal oxides, while at the same time being potentially lower in cost. Through modelling and experiments it was found that networks consisting of larger diameter nanowires have the highest near infrared transparency. Preliminary results of the integration of these nanowire electrodes into tungsten oxide based electrochromic windows will be presented.
I will then briefly discuss two pending projects in which silver nanowire networks will be used in flexible electrochromic displays. Both FTO and ITO are brittle, with their sheet resistance increasing upon bending. Furthermore, their deposition temperatures are not compatible with flexible substrates such as plastic and paper. In contrast, silver nanowires are both very mechanically flexible and can be deposited at room temperature. Silver nanowire networks will be combined with two material systems, tungsten oxide nanoparticles and the polymer PEDOT:PSS, to enable flexible, low-cost transparent displays on paper with improved performance.