Zn-Alloyed All-Inorganic Halide Perovskite-Based White Light-Emitting Diodes with Superior Color Quality

Abstract

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.

Performance Enhanced Light-Emitting Diodes Fabricated from Nanocrystalline CsPbBr3 with In Situ Zn2+ Addition

“…49 Zn-CsPbBr3 sample shows no significant shift in 2θ peak, indicating no obvious structural inclusion of Zn 2+ in the bulk of CsPbBr3 NCs. 42 The Zn-CsPbBr3 was polymorphic and contained ~30 wt% of cubic (Pm3̅ m a= 5.8 Å) CsPbBr3 along with orthorhombic CsPbBr3 (Figure 1 b, Figure S2) and significantly lower Rwp and Rexp values (Table S1). Cubic structure of CsPbBr3 is generally considered less conducting than an orthorhombic crystal structure of CsPbBr3.…”

“…Another passivation strategy is by additional metal cation doping/surface treatment. [40][41][42][43][44][45] A generic method introducing divalent cations such as Cd 2+ , Zn 2+ , Sn 2+ to CsPbBr3 nanocrystals is via hot-injection. 41 Moreover, the post synthetic cation exchange using Zn 2+ was also explored in chalcogenide nanocrystal and FA doped CsPbBr3 nanocrystal systems.…”

Yb2+-Alloyed Cs4PbI6–CsPbI3 Perovskite Nanocomposites for Efficient and Stable Pure-Red Emission

“…To improve the stability of perovskite NCs, metal elements alloying to replace part of lead has been proven to be a promising strategy by different research groups. − Such as, Mn 2+ , Sr 2+ , Zn 2+ , and Bi 3+ were alloyed into CsPbI 3 perovskite NCs − ,− to improve the stability of CsPbI 3 NCs at room temperature. However, these metal alloying strategies typically have minor effect on the PL peak position, and these alloyed CsPbI 3 NCs still have emission color at the near-infrared region.…”

Lead‐Free Halide Double Perovskite Nanocrystals for Light‐Emitting Applications: Strategies for Boosting Efficiency and Stability

“…The challenges and resolvable routes are followed: 1) The WLED devices fabricated by using HDPs as emitters still exhibit low luminous efficiency due to a weak absorption and low energy transfer efficiency in blue region. [ 184–187 ] Hence, designing highly efficient lead‐free single‐phase full‐color‐emitting HDPs with strong absorption in blue region may boost luminous efficiency of WLED devices. 2) The HDPs emitter with red emission is rarely reported.…”