Mg²⁺‐Alloyed All‐Inorganic Halide Perovskites for White Light‐Emitting Diodes by 3D‐Printing Method

Abstract

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.

Highly Efficient Blue‐Emitting CsPbBr3 Perovskite Nanocrystals through Neodymium Doping

“…The increased doping concentration also leads to peak broadening and splitting at 30.7°, which indicates a symmetry-lowering tilt and distortion of the [BX 6 ] 4− octahedron. [17,29] Such distortions are also predicted by our first principles calculations, but they are below 1.5°. It has been reported that doping can induce structural evolution, especially when the size mismatch between the dopant and substituted atoms is large, [29,31,36] but the calculated small distortion here indicates the lattice contraction and octahedral tilting are not strong enough to induce a distinct structural change.…”

“…[13] B-site cations also play a critical role in determining the electronic band structure of perovskites and consequently their emission properties. Recent studies have demonstrated successful B-site doping using alkaline-earth metal ions (Mg 2+ , Ba 2+ , Sr 2+ ), [14][15][16][17] transition metal ions (Cu 2+ , Cd 2+ , Ag + , Zn 2+ ), [18][19][20][21] metalloid ions (Sn 2+ , Bi 3+ ), [22][23][24] and lanthanide ions (Ce 3+ , Tb 3+ , Yb 3+ ). [25][26][27] Despite these advantages, dopants may also lead to negative effects on the properties of NCs.…”

Emergence of Impurity-Doped Nanocrystal Light-Emitting Diodes

“…To overcome the toxicity problem, more endeavors should be taken in the development of heavy-metal-free impurity-doped nanocrystal LEDs [ 353 , 354 , 355 ], otherwise it will be difficult to enter the mainstream display, lighting, and signaling markets. For the lifetime issue, no impurity-doped nanocrystal LEDs with satisfactory operational stability have been reported.…”

Color Tuning for Perovskite Light-Emitting Diodes

“…For instance, by blending blue CsPbBrxCl3-x QDs with orange polymer of poly[2-methoxy-5-(2-ethylhexyloxy)1,4-phenylenevinylene] (MEH:PPV) with the ratio of 9 : 1, a single-EML white LED with CIE chromaticity coordinates of (0.33, 0.34) was demonstrated ( Figure 5.3). [179] Other additional emitters, like rare-earth ion Sm 3+ , [180] alkali metal Mg 2+ , [181] also show good compatibilities with perovskites. Adapted from reference.…”