Lanthanides-doped luminescent materials have gathered considerable attention due to their application potential in stress sensing, lighting and display, anti-counterfeiting technology and so forth. However, existing materials mainly cover the 380–1540 nm range, with slight extension to the UV region, impeding their applications in solar-blind imaging, background-free tracking, concealed communication, etc. To address this challenge, here we propose guidelines for far-UVC (200–230 nm) optical design. Accordingly, we achieve multi-stimulated far-UVC luminescence at ~222 nm in Pr ³⁺-doped SrF ₂, stemming from the inter-configurational 4f5d → 4f  ² transition of Pr ³⁺. Besides Pr ³⁺, the SrF ₂ host shows high tolerance to Ce ³⁺, Nd ³⁺, Sm ³⁺, Eu ^2+,3+, Gd ³⁺, Tb ³⁺, Dy ³⁺, Ho ³⁺, Er ³⁺, Tm ³⁺ and Yb ³⁺, vastly extending the emission wavelength across the entire spectral range from 200 to 1700 nm. Particularly …