Temperature Dependent Fluorescence of CuInS/ZnS Quantum Dots in Near Infrared Region

The semiconductor nanocrystals (or quantum dots) have shown peculiar optical and electrical properties due to their exceptionally small size. In recent years tremendous researches on quantum dots have been carried out. Among them, QDs as sensing media for chemical and biological assay have achieved great progress. Quantum dots can generate a high-performance optical spectrum from visible to near infrared (NIR) region. However, the toxicity of quantum dots whose composition includes heavy metals such as cadmium (Cd), mercury (Hg), and lead (Pb) hinders the expansion of their applications in biological and medical areas. QDs with fluorescence emission in NIR spectral region are of great interest because in NIR region, biological materials usually show low background fluorescence, and fluorescence of QDs can penetrate into deep tissues. Although several researches have been reported on the temperature dependence of fluorescence of Cd based QDs, researches on QDs in NIR region can't be found. Therefore, in this study, we have investigated temperature dependent fluorescence of CuInS/ZnS quantum dots which show the emission peaks at the wavelength of 700, 750, and 800 nm. Linear relationship between PL intensity and temperature in the range of 30 degrees C to 90 degrees C has been observed.