Dual-excited anti-thermal quenching in SrGa 12 O 19 : Er 3+ , Yb 3+ , Cr 3+ phosphors: from thermochromism to NIR luminescence

Conventional phosphors suffer from thermal quenching, i.e., the loss of emission intensity with rising temperature. A promising, yet emerging solution is a new class of materials called anti-thermal quenching (ATQ) phosphors, capable of avoiding this issue and thus succeeding in applications where higher temperatures are expected. In this study, SrGa12O19: Er3+, Yb3+, Cr3+ phosphors were designed to display dual-excited ATQ. Under 980 nm excitation, the Yb/Er upconversion process causes the Yb3+→Er3+→Cr3+ energy transfer, resulting in a 2.7-fold Cr3+ intensity enhancement and an Sr-max of 2.88% K-1 at 480 K. Moreover, co-modulating excitation wavelength and thermal stimulation leads to a gradual change in the emission color from green to orange-red, which is an interesting feature for anti-counterfeiting optical markers. Finally, the downshifting process under 468 nm excitation triggers a reverse Cr3+→Er3+/Yb3+ energy transfer process. This efficient conversion from UV-visible light to NIR radiation shows high application potential in solar cells and LED devices.