Bright Blue Light Emission of Ni²⁺ Ion-Doped CsPbCl_xBr_3–x Perovskite Quantum Dots Enabling Efficient Light-Emitting Devices

Abstract

In recent years, significant advances have been achieved in the red and green perovskite quantum dot (PQD)-based light-emitting diodes (LEDs). However, the performances of the blue perovskite LEDs are still seriously lagging behind that of the green and red counterparts. Herein, we successfully developed Ni2+ ion-doped CsPbCl x Br3–x PQDs through the room-temperature supersaturated recrystallization synthetic approach. We simultaneously realized the doping of various concentrations of Ni2+ cations and modulated the Cl/Br element ratios by introducing different amounts of NiCl2 solution in the reaction medium. Using the synthetic method, not only the emission wavelength from 508 to 432 nm of Ni2+ ion-doped CsPbCl x Br3–x QDs was facially adjusted, but also the photoluminescence quantum yield (PLQY) of PQDs was greatly improved due to efficient removal of the defects of the PQDs. Thus, the blue emission at 470 nm with PLQY of 89% was achieved in 2.5% Ni2+ ion-doped CsPbCl0.99Br2.01 QDs, which increased nearly three times over that of undoped CsPbClBr2 QDs and was the highest for the CsPbX3 PQDs with blue emission, fulfilling the National Television System Committee standards. Benefiting from the highly luminous Ni2+ ion-doped PQDs, the blue-emitting LED at 470 nm was obtained, exhibiting an external quantum efficiency of 2.4% and a maximum luminance of 612 cd/m2, which surpassed the best performance reported previously for the corresponding blue-emitting PQD-based LED.

Mn2+/Yb3+ Codoped CsPbCl3 Perovskite Nanocrystals with Triple‐Wavelength Emission for Luminescent Solar Concentrators

“…Current studies focus mostly on doping a single‐type of metal ions into the host perovskite NCs, while few research efforts have been made on simultaneously doping more than one type of metal ions into the same perovskite hosts and intra‐particle energy transfer processes. [ 29–30,43–44 ] In particular, despite the high popularities of each dopant on their own, no studies have been reported so far about codoping both Mn 2+ and Yb 3+ ions concomitantly into one perovskite NC sample. Beneficially, compared to solely Mn 2+ doped CsPbCl 3 NCs, the co‐introduction of Yb 3+ dopants may lead to an increased total PL QY while maintaining the large Stokes shift for both Mn‐ and Yb‐emission bands with decreased reabsorption loss.…”

Emergence of Impurity-Doped Nanocrystal Light-Emitting Diodes

“…In this work, a maximum luminance of 11,800 cd m −2 was yielded, which was among the highest for blue PeLEDs. More recently, Song et al reported that the maximum EQE of Ni 2+ -doped blue CsPbBr 0.99 Cl 2.01 PeLEDs was up to 2.4%, which was the best for blue CsPbX 3 PeLEDs [ 317 ].…”

Surface Passivation Strategies for Improving Photoluminescence and Stability of Cesium Lead Halide Perovskite Nanocrystals

“…[35][36][37] Doping with metal ions like Cd 2 + , Ni 2 + which are smaller in size than Pb 2 + ion gives an enhancement of 20 folds in PLQY of CsPbCl 3 perovskite NCs. [38,39] To target the extrinsic stability of CsPbX 3 NCs towards heat, moisture, and oxygen, it is necessary to look for the approaches such as encapsulation in a polymer matrix, and developing core-shell structures. [40,41] Intriguingly, it is explored that embedding the CsPbX 3 perovskite NCs into a polymer matrix can improve its long-term stability for several months.…”

“…[43] Additionally, it has been proved that doping of sodium to protect CsPb(Br/I) 3 perovskite NCs during encapsulation with Al 2 O 3 to form Na: CsPb(Br/I) 3 @Al 2 O 3 nanocomposites makes them less vulnerable to moisture and light exposure. [44] So far, many approaches have been developed to attain high stability and photoluminescence of CsPbX 3 perovskite NCs like surface passivation, [45][46][47][48] metal doping, [35,36,38,49] modified synthesis procedures, [17,18,50,51] core-shell, [43,44,52] encapsulation, [42,53,54] etc (See Figure 2). These methods are very diverse and their outcomes are much varied.…”

“…The partial replacement of Pb 2+ cation with manganese or lanthanide ions gives rise to multi‐colour emission in visible and NIR regions in CsPbCl 3 perovskite NCs [35–37] . Doping with metal ions like Cd 2+ , Ni 2+ which are smaller in size than Pb 2+ ion gives an enhancement of 20 folds in PLQY of CsPbCl 3 perovskite NCs [38,39] …”