Enhancement on concentration quenching threshold and upconversion luminescence of β-NaYF4:Er3+/Yb3+ codoping with Li+ ions

• β-NaYF4:Er3+/Yb3+ microcrystals are synthesized via a facile hydrothermal method.
• Co-doped Li+ was used to enhance the UC luminescence of β-NaYF4:Er3+/Yb3+.
• The influence of Li+ on the quenching concentration of Er3+ was investigated.
• The green and red emission is enhanced 2 and 3.3 times, respectively.

The application of upconversion (UC) materials, especially in solar cells, is still constrained because of their lower UC efficiency. In this work, co-doped Li+ was used to enhance the UC luminescence of β-NaYF4:Er3+/Yb3+ microcrystals. The influence of Li+ on the quenching concentration of Er3+ was investigated. The UC emission intensity was significantly improved by introducing different concentrations of Li+ ions. After 4 mol% Li+ doping, the quenching concentration of Er3+ increases from 2% to 4 mol%. Meanwhile, the green and red emission is enhanced 2 and 3.3 times, respectively. The results indicate that both the emission intensity and the quenching concentration can be increased by Li+ doping.