BiOCl:Er³⁺ Nanosheets with Tunable Thickness for Photon Avalanche Phosphors

Efficient high-order upconversion/downconversion photon avalanche (PA) luminescence of Er³⁺ ions was observed from hydrothermally synthesized Er³⁺-doped BiOCl nanosheets excited at 980 nm. Accompanied by declining threshold power, significant enhancements of the emission intensity and cycle numbers of PA luminescence were achieved simultaneously by decreasing the thickness of the nanosheets. Comparable experiments indicated that modification of the PA process is mainly correlated with the scale-dependent internal electric fields (IEFs) as well as the multiphoton band transition of BiOCl nanosheets. The results of this work pave the way to renewing the construction conditions for rare-earth-doped PA nanophosphors.