Lifecycle assessment of critical material substitution: Indium tin oxide and aluminum zinc oxide in transparent electrodes

Indium tin oxide (ITO) is the most commonly used transparent electrode (TE) material. However, the supply of indium is at risk due to resource scarcity and geopolitical reasons. Aluminum zinc oxide (AZO) is a potential candidate for its replacement. In this study, a life cycle assessment (LCA) for the substitution of ITO by AZO in an LCD TV was investigated. The main objectives were to (1) evaluate the environmental impacts of substituting ITO by AZO considering their material properties, and (2) propose a new assessment method called the scenario difference method (SDM) to evaluate the environmental impact of material substitution. Using the SDM, the results indicate that it is highly possible to reduce the total environmental burden of an LCD TV by replacing ITO with AZO. The environmental burden in the use stage can be reduced substantially because of the lower electricity consumption of AZO attributed to its higher transparency.