Recently, lead halide perovskite nanocrystals (NCs) have gained tremendous attention in optoelectronic devices due to their excellent optical properties. However, the toxicity of lead limits their practical applications. Here, the synthesis of Zn2+-alloyed CsZnxPb1-xX3 (up to 15%) NCs is reported to achieve lead-reduced white light-emitting diodes (WLEDs). The incorporation of Zn2+ into CsPbX3 host NCs results in a lattice contraction, without altering the structure and morphology, which has a direct effect on the optical properties. The blue-shifts in the photoluminescence emission and increase in bandgap is observed while retaining high photoluminescence quantum yield. Then by engineering the different compositions of halides for 15% Zn2+-alloyed CsZnxPb1-xX3 NCs, tunable emission (411–636 nm) is obtained. Notably, the WLEDs are experimentally demonstrated employing the lead-reduced NCs (blue, green, yellow, and red). By varying the ratios of the amount of NCs, white lights with a tunable correlated-color temperature (2218–8335 K), an exemplary color-rendering index (up to 93) and high luminous efficacy of radiation (268–318 lm·W−1) are obtained. Best of our knowledge, these are superior to other reported WLEDs based on CsPbX3 NCs doped with transition metal ions. This work places the halide perovskite NCs one-step closer in designing the environmentally benign and energy-efficient WLEDs.

All‐inorganic halide perovskites (CsPbX3, X = Cl−, Br−, and I−) are brought to the forefront of research focus in the field of modern lighting technology. However, due to the toxic element (Pb2+), environmentally friendly white‐light emissions are difficult to achieve, thus limiting their practical applications. Herein, high‐quality Mg2+‐alloyed CsPb1−x Mgx X3 (up to 20%) nanocrystals (NCs) are synthesized. The structural and optical properties are investigated. The application of these NCs in white‐light‐emitting diodes (LEDs) is also demonstrated. The incorporation of Mg2+ into CsPb1−x Mgx X3 NCs results in a lattice contraction without a change in structure and morphology, blue‐shifts in the photoluminescence emission, and increased bandgap. Then, the tunable emission (≈408–650 nm) is obtained by adjusting the compositions of different halides (for 20% Mg2+). Most importantly, for the first time, 3D printed thin color conversion layers for different color emitting NCs (green, yellow, and red) are stacked on top of the blue‐LEDs to achieve high‐quality white light emission. A bright neutral white‐light with a correlated‐color temperature of 5806 K, a high color‐rendering index of 89, CIE coordinates of (0.32, 0.33), a small Duv (<0.003), and high luminous efficacy of radiation of 280 lm W−1 is achieved.

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The long-term stability issue of metal halide perovskite nanocrystals (NCs) is one of the challenges for applications in optoelectronic devices. Herein, we demonstrate the enhanced air, moisture, and light stability of these NCs by encapsulation in UV resin (UVR). As-prepared perovskite NCs-UVR composites exhibit well maintained optical properties. In addition, the composites show excellent stability with almost identical luminescent behavior for more than 60 days upon continuous exposure in air, moisture, and light irradiation, which is superior to the other previous reports. Moreover, we have used these green- and red-emitting composite sheets to fabricate white light-emitting diodes (LEDs) by stacking them on top of the blue LED. We observed a bright neutral white light with a correlated-color temperature of 5623 K, a color-rendering index of 85, and a high luminous efficacy of radiation (∼349 lm/W). Our findings show the great potential of employing this technique for diverse photonic applications.