Temperature-tunable upconversion luminescence of perovskite nanocrystals KZnF3:Yb3+,Mn2+

Abstract

Temperature-tunable intense yellow upconversion luminescence has been demonstrated in perovskite nanocrystals KZnF₃:Yb³⁺,Mn²⁺ upon excitation with a 976 nm laser diode. The broad yellow luminescence band is centered at 585 nm and identified as the ⁴T_1g(G) → ⁶A_1g (S) transition of Mn²⁺. An upconversion luminescence mechanism based on exchange coupled Yb³⁺–Mn²⁺ dimer is proposed and the upconversion process consists of a sequence of ground state absorption (GSA)/excited-state absorption (ESA) steps. To understand thermal quenching behavior, temperature dependent upconversion luminescence of KZnF₃:Yb³⁺,Mn²⁺ during heating and cooling cycles have been investigated. Results show the yellow upconversion luminescence can be seen by the naked eyes at temperatures up to 573 K and the thermal quenching is reversible. The intense yellow upconversion nanocrystals KZnF₃:Yb³⁺,Mn²⁺ might find potential applications in the fields of lighting, temperature sensing, biomedical imaging and solid state lasers.