Achieving Tunable Cold/Warm White-Light Emission in a Single Perovskite Material with Near-Unity Photoluminescence Quantum Yield.

Single materials that exhibit efficient and stable white-light emission are highly desirable for lighting applications. This paper reports a novel zero-dimensional perovskite, Rb ₄ CdCl ₆ :Sn ²⁺ _, Mn ²⁺ , which demonstrates exceptional white-light properties including adjustable correlated color temperature, high color rendering index of up to 85, and near-unity photoluminescence quantum yield of 99%. Using a co-doping strategy involving Sn ²⁺ and Mn ²⁺ , cyan-orange dual-band emission with complementary spectral ranges is activated by the self-trapped excitons and d-d transitions of the Sn ²⁺ and Mn ²⁺ centers in the Rb ₄ CdCl ₆ host, respectively. Intriguingly, although Mn ²⁺ ions doped in Rb ₄ CdCl ₆ are difficult to excite, efficient Mn ²⁺ emission can be realized through an ultra-high-efficient energy transfer between Sn ²⁺ and Mn ²⁺ via the formation of adjacent exchange-coupled Sn-Mn pairs. Benefiting from this efficient Dexter energy transfer process, the dual emission shares the same optimal excitation wavelengths of the Sn ²⁺ centers and suppresses the non-radiative vibration relaxation significantly. Moreover, the relative intensities of the dual-emission components can be modulated flexibly by adjusting the fraction of the Sn ²⁺ ions to the Sn-Mn pairs. This co-doping approach involving short-range energy transfer represents a promising avenue for achieving high-quality white light within a single material.
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