Upconversion Red Emission and Near-Infrared Quantum-Cutting Persistent Luminescence of Nd3+-Activated Ca2SnO4Induced by Yb3+

In this work, we have investigated the near-infrared (NIR) photoluminescence, upconversion (UC), and long-lasting phosphorescence properties of Nd3+/Yb3+-doped Ca2SnO4phosphors. Two-photon NIR quantum cutting (QC) luminescence is observed when the Nd3+–O2–charge-transfer band in Ca2SnO4:Nd3+, Yb3+phosphors was excited, and the theoretical quantum yield is found to be close to 200%. More interestingly, the unique two-photon UC red emission under 808 nm laser diode excitation and NIR QC persistent luminescence can be realized only in Nd3+–Yb3+codoped samples. The energy-transfer mechanism between Nd3+and Yb3+is revealed from the energy level structure and decay measurements. Different cross-relaxation schemes related to 2F5/2–2F7/2of Yb3+and f–f transition of Nd3+are proposed. The results show that multifunctional luminescence properties are achieved in Nd3+-doped Ca2SnO4with the introduction of Yb3+.