7. Synthesis and Characterization of Quantum Cutting Phosphor Materials

The rare earth ions produce photoluminescence in the entire range of the electromagnetic spectrum particularly in the UV, vis and NIR regions. The present chapter describes the synthesis of quantum cutting phosphor materials using different methods, such as solid-state reaction, combustion, sol–gel, hot-injection, hydrothermal, along with a melting-quenching method for the glass materials and studies the photoluminescence of the rare earth doped quantum cutting phosphor materials. Quantum cutting (QC) is a downconversion (DC) process in which the conversion of a high-energy photon into the two or more low-energy photons takes place. This process not only takes place in the singly rare earth doped materials but also in the doubly and/or triply rare earth doped materials. The difference is only in the energy transfer route between activator and sensitizer ions. This occurs due to cooperative energy transfer (CET) process. In energy transfer process, the photoluminescence intensity of sensitizer ion decreases whereas the photoluminescence intensity of activator ion increases accordingly. The change in photoluminescence intensity of these ions is highly concentration dependent. The photoluminescence intensity versus pump power measurements shows that the photoluminescence intensity of the visible region is a linear process while that of the NIR region occurs due to nonlinear process. The change in photoluminescence intensity of the sensitizer ions can be established from the lifetime measurements. The preparation and characterization of different rare earth-based quantum cutting materials and their applications in large numbers of the emerging fields have been also included.