A Visual Solar UV Sensor Based on Paraffin-Perovskite Quantum Dot Composite Film.

Nowadays, people are facing more and more threats from solar UV radiation due to global ozone layer depletion and the ozone hole. Therefore, it is highly desirable to develop a fast, simple, and sensitive sensor for solar UV radiation. In this work, recently emerging perovskite quantum dots (PQDs) with excellent optical properties are used for sensing solar UV radiation. PQDs with high quantum yields are protected in solid paraffin to obtain paraffin-PQD composite (P-PQD) film. The hydrophobic and compact paraffin not only can protect PQDs from degradation by water and air for long-term use but also is transparent to UV light and thus maintains the high quantum yield of PQDs. The P-PQD film shows high sensing sensitivity for solar UV radiation based on which a novel visual ratiometric luminescence sensing strategy for UV light has been developed. The visual ratiometric luminescence sensor for solar UV radiation adopts a paraffin-encapsulated red fluorescence PQD (P-r-PQD) film as the sensing unit for UV light and a green luminescence light-emitting diode as reference light. When exposed to different solar UV radiation, the sensing film shows wide color variations from green to red, which can easily observed by the naked eye or recorded by a camera. On the basis of this, a simple and visualized solar UV index-reporting system has been established.