Insights into the Photostability of Ag–In–S–Zn Quantum Dots/Photopolymer Composites for Flexible Textile Applications

Heavy-metal-free Ag–In–Zn–S quantum dots (AIZS QDs) stand as promising alternatives to the well-known cadmium or lead-based QDs. Similarly to their copper counterparts, alloyed or core/shell AIZS QDs exhibit size- and composition-dependent photoluminescence (PL), which can be tuned from the visible to the near-infrared. The current challenge lies in preserving the exceptional optical properties of these nanocrystals, which are known to be particularly susceptible to environmentally induced degradation. Although rigid polymers have been regarded as viable stabilizing host materials, flexible polymers are being actively investigated, as they offer a wider range of applications. Synthesized via a hot-injection method, the studied AIZS QDs were confined inside a flexible acrylate matrix and UV-polymerized onto textile substrates in less than 30 s. The resulting materials exhibited intense yellow PL but underwent photobleaching under LED exposure (emission loss over 55% after 30 min). After the degradation processes at play were identified, several stabilizing strategies were addressed by modifying either the nanocrystal structure or the polymer matrix. The most efficient involved confining the QDs inside flexible acrylate hydrogels, which reduced the PL emission loss from 55% to below 10% after 30 min of LED irradiation and enabled a sustained PL enhancement of up to +125% under continuous illumination over 15 days in humid/aqueous environments.