Assessing Stability of Nanocomposites Containing Quantum Dot/Silica Hybrid Particles with Different Morphologies at High Temperature and Humidity

In this study, we investigate the photoluminescence stability of nanocomposites containing quantum dot (QD)/silica hybrid particles against high temperature and humidity. First, hybrid particles with different morphologies, such as silica/QD/silica (SQS), QD/mesoporous silica (MSQ), and QD/wrinkled silica (WSQ), were synthesized and dispersed in a commercially available silicone resin (Sylgard-184). We performed stability tests on these nanocomposites at 100 °C/85% RH for 72 h and found that their quantum efficiencies were maintained or even increased during the test, whereas a nanocomposite containing bare QDs exhibited a significant decrease in quantum efficiency. The enhancement in quantum efficiencies of the nanocomposites containing the MSQ and SQS particles was attributed to the photoactivation phenomenon. To further investigate the stability after exposure to heat and moisture, we measured quantum efficiencies of the photoactivated nanocomposites after storing them for 10 days under ambient conditions. Those efficiencies significantly decreased to values even lower than the initial values. However, quantum efficiency of the nanocomposite containing WSQ particles remained constant during and after the stability test because of the particle morphology. Therefore, we conclude that the nanocomposite containing the WSQ particles was most stable against high temperature and humidity and that the photoactivation was not desirable for the stability of nanocomposites, although it initially enhanced the photoluminescence properties.