Unlocking the Effect of Trivalent Metal Doping in All-Inorganic CsPbBr₃ Perovskite

Abstract

Metal-ion doping is one of the most efficient approaches to precisely control the electronic and optical properties of perovskite nanocrystals (NCs). However, the origin of the dramatic contrast in the photoluminescence (PL) behavior of CsPbBr3 NCs incorporating bismuth (Bi 3+) and cerium (Ce 3+) ion dopants remains unclear. Here, we demonstrate dominant PL quenching/enhancing centers both in the bulk and on the surface of Bi 3+ /Ce 3+ doped CsPbBr3 by calculating the dopant defect formation energies and charge-transition levels using high-level density functional theory (DFT). We show that the Bi 3+ dopants introduce deep trap-states (antisite BiPb and interstitial Bii) that are responsible for PL quenching. In sharp contrast, the Ce 3+ dopants enhance the CsPbBr3 lattice order and enrich the conduction band-edge states through antisite CePb, causing PL enhancement. Our findings not only provide new physical insights into the mechanism of the trivalent metal-ion doping effect, but also suggest a new strategy to control the dopant defect states for improving the optical performance of perovskite nanocrystals.

Highly Efficient Blue‐Emitting CsPbBr3 Perovskite Nanocrystals through Neodymium Doping

“…Our results are consistent with previous calculations. [38][39][40] The band structure calculations with Nd dopants at Pb sites show that the bandgap increases with increasing doping concentration. Figure 4c depicts the electronic structure of CsPbBr 3 :xNd 3+ (x = 12.5%), in which the bandgap increases from 2.34 to 2.59 eV.…”

Switching on Near-Infrared Light in Lanthanide-doped CsPbCl3 Perovskite Nanocrystals.pdf

“…The BE emission lifetime increases after Er 3+ doping indicates a decrease of nonradiative trap states or enhanced lattice order. [44] The remarkable shortening of the BE carrier lifetime in the presence of Mn 2+ with respect to the undoped NCs is in fact consistent with the efficient energy de-excitation of the CsPbCl3 matrix by the activation of Mn 2+ higher energy states, giving rise to the characteristic broad (FWHM ≈ 90 nm) Mn 2+ emission band centered at ~600 nm, corresponding to the 4 T1 → 6 A1 transition, [36,45] On the other hand, the extremely weak PL intensity of the Ln 3+ f-f emission bands in the NIR range (Figures 2e-g), and the increased intensity and lifetime of the BE carrier, are indicative of a very inefficient Ln 3+ sensitization in the singly Ln 3+ -doped samples due to big energy gaps between the conduction band (CB) of the CsPbCl3 host and the emitting levels of Ln 3+ . Furthermore, the introduction of Ln 3+ in the CsPbCl3 matrix is likely to induce a removal of deep trap states related to Cl − vacancies [26] or enhanced lattice order through host relaxation, [44] thus leading to BE emission improvement.…”

Lanthanide doping in metal halide perovskite nanocrystals: spectral shifting, quantum cutting and optoelectronic applications

“…In a different direction from quantum cutting for improving the efficiency of Si solar cells, lanthanide doping has been reported to increase the efficiency and stability of perovskite solar cells 38,[43][44][45] . Ln 3+ doping has been reported to reduce lattice and surface defects of both NCs and bulk-like perovskite thin films 32,38 . Figure 4g, h shows that the solar cell performance of CsPbBr 3 thin films significantly improves with various lanthanide doping.…”