Tailoring the upconversion of ABF3:Yb3+/Er3+ through Mn2+ doping
Successful upconversion (UC) tuning from multi-bands to one single red band from Er3+ ions was realized in cubic perovskite ABF3:Yb3+/Er3+ (A = K, Cs; B = Zn, Cd) through Mn2+ doping. Based on UC emission spectra and decay kinetics of KZnF3:Yb3+/Er3+ with different Mn2+ contents, a bidirectional energy transfer process between Mn2+ and Er3+ ions was confirmed to explain the UC tuning mechanism. More importantly, we studied the influence of the Mn2+ energy level position on the UC properties for Er3+ in ABF3 hosts. Interestingly, great enhancement of green UC emissions was observed for Er3+ ions in KCdF3 and CsCdF3 hosts upon Mn2+ doping. Comparison of UC emissions and lifetimes of Er3+ ions in the three materials was carried out to probe the different UC processes in ABF3 (A = K, Cs; B = Zn, Cd) hosts. The different energy transfer mechanism between Mn2+ and Er3+, which is affected by the Mn2+ energy level position, was proposed to explain the UC difference in the three matrices. This research convincingly confirmed the occurrence of energy transfer between Er3+ and Mn2+ ions and provided deep insights into the importance of the Mn2+ energy level position in tuning the UC properties of Er3+ in diverse hosts, while allowing us to better control the UC properties through Mn2+ doping.
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