A Guanidinium-Based Mn⁴⁺-Doped Red-Emitting Hybrid Phosphor with High Stability

Great efforts have been put in search of phosphors to fulfill the requirements for phosphor-converted white light-emitting diodes (pc-WLEDs). Herein, a general organic–inorganic hybridization strategy was demonstrated in Mn⁴⁺-, Cr³⁺-, or Eu³⁺-doped guanidinium-based zero-dimensional hybrid fluorides to find phosphors for pc-WLEDs. Among which, GA₃AlF₆:Mn⁴⁺ (where GA represents the guanidinium cation [C­(NH₂)₃]⁺) was selected to reveal their crystal structure, local symmetry, and luminescence properties. Density functional theory calculations suggested that GA₃AlF₆ with a wide band gap (∼5.24 eV) and the F_i^′ interstitials are generated to balance the charge differences caused by non-equivalent doping. The GA₃AlF₆:Mn⁴⁺ hybrid could sustain ∼573 K high temperature without degradation and keep 90.1% of the original luminescence intensity at ∼373 K. A pc-WLED with wide color gamut (108.3%) of National Television System Committee standard was fabricated with GA₃AlF₆:Mn⁴⁺, suggesting its potential in high-quality backlight displays. This work not only brings a brand-new kind of organic–inorganic fluoride phosphor family but also provides great guiding significance for future exploration of fluoride-based functional materials containing a hybrid structure.