Novel double perovskite Cs₂Na_0.7Ag_0.3InCl₆: Mn²⁺ for deep UV chip-based high color-rendering WLEDs

The commercial potential of traditional double perovskites in white light-emitting diodes (WLEDs) has been constrained by low photoluminescence quantum yield (PLQY) and narrow emission spectrum, mainly due to parity-forbidden transitions and indirect bandgap characteristics. To address these issues, Ag ⁺ doped Cs₂NaInCl₆ (CNIC) are synthesized via solvothermal method. Compared to the undoped sample exhibiting a low PLQY of 2.76%, Ag⁺ doped samples show a high PLQY of 77.56%, attributing to STEs emission of 540 nm. Additionally, a series of Cs₂Na_0.7Ag_0.3InCl₆: xMn²⁺ novel materials are designed. The results demonstrate that an energy transfer pathway from STEs to Mn²⁺ in co-doped system, enabling tunable dual emission across the entire visible spectrum. Notably, Cs₂Na_0.7Ag_0.3InCl₆: xMn²⁺ materials can be effectively excited by deep-ultraviolet (deep-UV) light. A WLEDs device is fabricated by coating this novel material and commercial BaMgAl₁₀O₁₇:Eu²⁺ blue phosphor on deep-UV chip, producing warm white light with a CIE coordinate of (0.3609, 0.3576), a correlated color temperature (CCT) of 4460 K and a high color rendering index (CRI) of 87.9. These results show that Cs₂Na_0.7Ag_0.3InCl₆: xMn²⁺ novel materials have potential for application in solid-state lighting.