ZnO quantum dots-diacetylenes-zinc(II) nanocomposites for colorimetric detection of ultraviolet-B light: the size effects

Abstract

Polydiacetylenes (PDAs) are color-responsive materials that have shown potential as colorimetric sensors for detecting various classes of analytes. However, the utilization of PDAs for sensing ultraviolet-B light (UVB) is rare. This contribution introduces a facile method for enhancing the UVB-responsive property of PDAs by incorporating zinc oxide (ZnO) quantum dots (QDs). We explore the size effects of ZnO QDs/nanoparticles and diacetylene (DA) monomers on the sensitivity of the resultant nanocomposites to UVB light. Interestingly, the sensitivity of nanocomposites to UV light with different wavelengths can be controlled by adjusting the size of ZnO nanoparticles. We have found that the incorporation of ZnO QDs with diameters ranging from 2.2 to 3.8 nm drastically increases the sensitivity to UVB light. In addition, fine-tuning of the UVB sensitivity can be achieved by varying alkyl chain lengths of the DA monomers. The colorimetric response of nanocomposites to specific UVB regions can be obtained by adjusting the band gap of ZnO QDs. This property allows their utilization as colorimetric sensors for detecting UVB doses in sunlight and other sources. Colorimetric UVB sensors can be fabricated in different forms including smart ink sensors, free-standing flexible sensors, paper-based sensors, and hydrogel-based sensors.