Neodymium Chloride-Doped Perovskite Nanocrystals for Efficient Blue Light-Emitting Devices

Abstract

Metal halides doping of perovskite nanocrystals (NCs) has been shown to precisely control nonradiative pathways and to improve photoluminescence quantum yield (PLQY). Here, we report a trivalent lanthanide halide neodymium (III) chloride (NdCl3)-doped perovskite NCs prepared with a post-synthetic room temperature treatment for efficient blue light-emitting devices (LEDs). The Nd 3d and Cl 2p core peaks were observed in the NdCl3-doped NCs, which allowed for simultaneous doping of Nd3+ and Cl– into the pristine CsPbBr3 NCs. The NdCl3-doped NCs exhibited blue emission at a peak wavelength of 478 nm with a high PLQY of 97% in solution. We found that the Nd3+ cation incorporated into the NCs more effectively suppressed nonradiative recombination compared with common halide anion exchange from temperature dependence of optical properties. Blue LEDs based on NdCl3-doped NCs had an external quantum efficiency of 2.7%, which represents a considerable performance improvement compared with LEDs based on organic chloride salt-doped NCs.

Challenges and Opportunities for the Blue Perovskite Quantum Dot Light-Emitting Diodes

“…For PQDs, the uniform size distribution, homogenous crystal structure and low trap density [30] are the key factors for narrow FWHM. Ultra-narrow FWHMs are witnessed for PQD-LEDs based on Nd 3+ modified CsPbBr x Cl 3−x with merely 14 nm at 481 nm [20], 14 nm at 463 nm for undoped CsPbBr x Cl 3-x [32] and inspiring 12 nm at 463 nm for CsPbBr 3 [33], while most blue 2D/quasi-2D PeLEDs are with mediate-narrow FWHMs of around 25 nm.…”

“…The A site and B site vacancies can be passivated by ion doping. As Chiba et al [20] summarized in their work, transition metals (including Mn 2+ , Ni 2+ , Cd 2+ , Y 3+ , etc. ), alkaline metals (include Ca 2+ , Sr 2+ ), Lanthanoids (include Ce 3+ and Eu 3+ ) and some other bivalent or trivalent metal ions such as Sn 2+ , Mg 2+ and Bi 3+ are capable of defect passivation.…”

Recent Advances in Blue Perovskite Quantum Dots for Light‐Emitting Diodes

“…Interestingly, the analogous divalent ions such as Ni 2+ and Nd 2+ ions have similar impacts on mixed-halide PQDs, which could also be incorporated into the lattice to boost PL QY and enhance stability. [102,122,157,158] The blue emission can be tailored by not only mixing halides and quantum confinement effect, but also doping metal ions into all-bromide PQDs. Figure 8e-g show tunable blue emission of CsPbBr 3 PQDs by the substitution of Pb 2+ with isovalent cations (Sn 2+ , Cd 2+ , and Zn 2+ ), [138] where the blue shift of the absorption and PL spectra was observed in all cases.…”

“…[157] Additionally, NdCl 3 dopant enhanced the colloidal stability of CsPbBr x Cl 3−x PQDs and the corresponding device had a small voltage shift during the operation. [158] Compared to lead-based perovskite electronic devices, the PeLEDs fabricated by lead-free PQDs exhibited remarkable operating stability. [162,176,187] Wang and co-workers reported a deepblue PeLED based on Cs 3 Cu 2 I 5 PQDs, which reached a high EQE of 1.12% with the Commission Internationale del'Eclairage (CIE) color coordinates of (0.16, 0.07) [162] (Figure 13a).…”

Environment‐Friendly Perovskite Light‐Emitting Diodes: Progress and Perspective

“…In general, the possible elements for B-site substitution include tin (Sn), germanium (Ge), antimony (Sb), strontium (Sr), calcium (Ca), manganese (Mn), copper (Cu), zinc (Zn), cerium (Ce), yttrium (Y), neodymium (Nd), ytterbium (Yb), europium (Eu), and so on. [18][19][20][21][22][23][24][25][26][27][28][29][30] So far, although some works have summarized the influence of B-site doping in perovskite, the benefit in respect of reducing toxicity was ignored. [31][32][33] Similarly, several review articles have been published on different kinds of lead-free perovskite materials and their applications.…”