The incorporation of quantum dots (QDs) into display technologies can greatly enhance colour accuracy, peak brightness, and energy efficiency for display devices due to their tunable bandgaps and near-perfect luminescent properties. Increasing demand for QD displays has driven the adoption across various consumer electronics, with notable examples of TV sets and tablet computers. The state-of the-art commercial QD displays, however, contain cadmium (as CdSe) and may exhibit human and environmental hazards upon exposure at the <i>end-of-life</i> stage, such as landfill disposal. The relatively less toxic indium-based QDs (as InP), on the other hand, are far more energy intensive than CdSe QDs to manufacture, especially for large-scale applications. Therefore, rather than basing environmental decisions solely on material hazard, a systematic approach considering various life cycle stages of QD displays is necessary to avoid unintended shifting of environmental burden. In this study, we employed two types of electronic devices (i.e., tablet and TV set) to assess the environmental impacts of Cd-based and Cd-free QDs in displays with on-edge and on-surface technologies. Chemical composition and structure of QDs within the light control polymeric films were determined with ICP-MS and X-ray fluorescence spectroscopy. The release and transformation of QDs at the end-of-life phase was also evaluated with toxic characteristic leaching procedure (TCLP) and waste extraction test (WET) procedures. Our work shows that both Cd and Cd-free QDs in the displays are mostly liberated as metal ions or metal oxides instead of in their pristine nano-form. Also, since QDs are complexed with amino silicones and confined in the polymer matrix, the released amount is limited and in the scale of ng/cm<sup>2</sup>. The study demonstrates that the assessment of life cycle stages, in addition to the manufacturing phase, are important to make product-design and policy decisions for the development of sustainable QD displays.

Release of QDs from consumer electronics for sustainability evaluation of competing QD-enabled displays

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.