All-Inorganic Lead-Free Doped-Metal Halides for Bright Solid-State Emission from Primary Colors to White Light

Metal halides have been explored with the aid of strongphotoluminescencefor optical and optoelectronic applications. However, the preparationof lead (Pb)-free solid-state emitters with high photoluminescencequantum yields (PLQYs) and tunable emission remains exceptionallychallenging. Herein, we report metal ion (Cu(I), Mn(II), and Sn(II))-dopedCs(3)ZnI(5) single crystals that are primary color(violet, green, and orange/red) emitters with extremely high PLQYs.Whereas the Mn-doping leads to bright green emissions with 100% PLQY,the Cu- and Sn-doping give rise to blue and red emissions with PLQYsof 57 and 64%, respectively. Interestingly, higher Mn doping resultsin white light emissive crystals as a side product, which are foundto be Mn-doped CsI single crystals. The bright white light emissivecrystals can be synthesized in a pure form in large quantities andexhibit a high color rendering index (CRI) of 78 and CIE coordinatesof (0.30, 0.38), which are close to daylight conditions. To the bestof our knowledge, this is the first demonstration of white light emissionfrom a complete inorganic system. Importantly, the single crystalsof all colors exhibit high long-term stability as their PLQY remainsunchanged even after 2 months of preparation, and are thermally stableup to 600 & DEG;C.

Automated summary

Metal ion-doped Cs(3)ZnI(5) single crystals are primary color (violet, green, and orange/red) emitters with high photoluminescence quantum yields (PLQYs), including 100% PLQY for bright green emission with Mn doping, 57% PLQY for blue emission with Cu doping, and 64% PLQY for red emission with Sn doping. In addition, high Mn doping results in white light emissive crystals, which is the first demonstration of white light emission from an inorganic system. All colored single crystals exhibit high long-term stability and thermal stability up to 600℃.