Photoluminescent Ozone Sensor with Enhanced Sensitivity by Using CdSe/ZnS Quantum Dots Modified with Gold and Platinum.

We report photoluminescence-based ozone sensing using composite films composed of gold or platinum and red-emitting CdSe/ZnS core-shell quantum dots. The sensing efficiency of quantum dots is enhanced by the addition of noble metals. The composite films undergo reversible changes in photoluminescence intensity (measured at excitation/emission wavelengths of 365/652 - 659 nm) in the presence of ppm levels of ozone in air at 25°C and at atmospheric pressure. The sensitivity of the composite films does not saturate with ozone in the 0.5 - 200 ppm concentration range. When compared with a quantum dot-only film, the composite films show higher sensitivities to 0.5 ppm ozone of 27% (gold) and 43% (platinum). When compared with a quantum dot-only film, the photoluminescence of the gold- or platinum-palladium alloy-based film recovers faster after the removal of ozone in the surrounding atmosphere. Thus, platinum- or gold-conjugated quantum-dot films form sensor modules for the reversible and highly sensitive detection of ozone under the tested ambient conditions.