Recycling of Waste Polymethyl-Methacrylate as an Optical Transparent Host

Reusing waste or otherwise discarded polymethyl methacrylate (wPMMA) as a host matrix for optical photonic applications such as down-conversion or luminescence solar concentrators can spare the use of pristine materials, with strong implications for sustainability. Here, a homogeneous emissive film was produced using wPMMA by dissolving in toluene and adding a fluorescent perylene dye (perylene-3,4,9,10-tetracarboxylic hexyl ester, PTHE) followed by spin coating casting. This resulting film is optically transparent and green-emissive with a high photoluminescence quantum yield (PLQY of 84%). It has been investigated by various spectroscopic techniques such as absorption, photoluminescence, emission lifetime, and dye photostability. While this film exhibited some excimer PL at longer wavelengths compared to the solution phase, it also increased its emission lifetime by approximately 3 times. Moreover, while the CIE coordinates (x, y) of the blue-green PL in the solution phase was 0.21, 0.56, the PL spectrum of the wPMMA:PTHE film instead had (CIE, x, y) of 0.30, 0.60. Recycling these and similar suitable waste polymers and transforming them into value-added products such as down-conversion or luminescent solar concentrator films can contribute to sustainable development goals within the scope of clean energy, energy efficiency, and waste utilization.