Abnormally heat-enhanced Yb excited state lifetimes in Bi7F11O5 nanocrystals and the potential applications in lifetime luminescence nanothermometry

Abstract

A heating-induced monotonous increase in the Yb³⁺ excited state (²F_5/2) lifetimes is found in Yb³⁺ single doped Bi₇F₁₁O₅ nanocrystals, possibly due to the thermal-enhanced photocarrier separation in polarized layered semiconductors with spontaneous internal electric fields. This unique phenomenon is evaluated for its thermometric performance in terms of lifetime luminescence thermometry, and the maximum absolute/relative temperature sensitivity (S_a/S_r) reaches as high as 0.65 μs K⁻¹/0.24% K⁻¹ in biological temperature regions. The results of this work can offer great potential for lifetime luminescence thermometry in biological areas and provide ideas for designing efficient photonic and photoelectric thermal devices.