Ultrasensitive Phosphorescence Sensors

Fluorescence spectroscopy as the most widely used luminescence-based imaging technique has extended applications in detection systems. However, fluorescence spectroscopy also has some limitations such as a relatively low signal-to-noise ratio in biological applications due to the autofluorescence of living tissues. In this context, the phosphorescence spectroscopy has promising potentials given its higher emission lifetime and Stokes shift compared to the fluorescence, increasing both signal resolution and selectivity. Furthermore, the autofluorescence signal interference issue can also be eliminated by incorporating phosphorophores in imaging and detection applications. Considering their unique characteristics, phosphorescent materials have recently found wide applications ranging from organic light-emitting diodes and photovoltaic cells to sensing systems and bioimaging. In the current chapter, the basic theory of luminescence as well as the main differences between fluorescence and phosphorescence are elaborated. In addition, state-of-the-art applications of phosphorescent materials, particularly room temperature phosphorescence and quantum dots in sensing systems, and general design considerations of these systems are also discussed. Finally, bioimaging based on phosphorescence detection systems is discussed.