Faculty Sponsor's Department:
Transparent electrodes are crucial components for modern electronics such as touchscreens, OLEDs, and photovoltaics. Indium tin oxide is a widely used material when both transparency and electrical conductivity are required. However, due to indium’s high cost, low supply, and lack of flexibility, alternatives are being investigated. In our group, a nanoimprinting process was devised where ultrathin gold nanowires (AuNWs) with high aspect ratio are assembled into flexible metal grids with gaps allowing for sufficient optical transparency. The resulting electrodes, however, are unstable, displaying rapid decay in conductivity over time. Different methods were used to investigate the mechanism behind this decay and find ways to slow or stop it. We varied different parameters including temperature, imprinting speed, and concentration to study their effects on the electrode stability. Scanning electron microscopy (SEM) allowed us to follow the electrode morphological changes over time and to relate them to the change in optical transmission as observed by UV-vis spectroscopy. Using a digital multimeter, the initial development of the electrode sheet resistance with time could be monitored in great detail via continuous, automated measurements. This allowed us to better characterize the time dependency of the electrode decay and the effect of various surface modifications that could potentially stabilize the electrodes.