The mechanism of alkali doping in CsPbBr3: A first-principles perspective

Abstract

All-inorganic CsPbBr3 perovskite doped with alkali metal atoms has been attracting increasing attention due to its superior optoelectronic properties. However, there still exists significant uncertainty regarding the doping mechanism. One view of the mechanism is that alkali metal atoms tend to substitute Cs in CsPbBr3 crystals. Another view is that Li and Na tend to intercalate into interstitial sites because their radii are much smaller than that of Cs. To elucidate the doping mechanism, it is necessary to investigate the point defects physics of alkali metal elements in CsPbBr3. In this work, by using first-principles calculations we find that alkali metal atoms energetically prefer to substitute for Cs or Pb atoms in CsPbBr3 crystals under different chemical potential conditions. To determine the alkali metal atoms doping site, one should consider the chemical potential of synthesis conditions, the dopant valence states, and atomic radii. Notably, alkali metal atoms doping mainly introduces shallow levels, which is helpful for improving the p-type conductivity of CsPbBr3.

Electronic, Optical, Thermoelectric and Elastic Properties of RbxCs1−xPbBr3 Perovskite

“…All-inorganic lead APbI 3 perovskites (with A = K, Li, Na or Cs cations), made via a self-organization process approach at room temperature, were experimentally explored by Dimesso et al They discovered that the A cation size has a small impact on how these APbI 3 perovskites’ bandgap energies change. Rb and K atoms have similar atomic radii to Cs, thus the correlation effect may be minimal [ 49 ]. The bandgap energy for CsPbBr 3 with a cubic crystal structure was calculated by Qian et al, using the density functional theory (DFT) approach.…”

Trends for Acceptor Dopants in Lead Halide Perovskites

“…While silver has been touted as an effective impurity dopant for achieving p-type CsPbBr 3 material, 16,17 acceptor doping with alkali metals on the Pb site has also been discussed in prior calculations. 18 Experimentally, doping of Na into CsPbBr 3 has also been reported to improve LED efficiency and nanocrystal stability. 19 However, the behavior of these dopants in other halide perovskites is not well understood.…”

First-Principles Survey of Acceptor Dopants for p-Type Cesium Lead Bromide

“…So far, silver has proven to be the most effective dopant for p-type CsPbBr 3 nanocrystals. , Acceptor doping by substituting alkali metals on the Pb site has also been suggested and experimentally reported in the case of sodium . Lithium has mostly been discussed on an interstitial site, where it acts as a donor, − with little consideration given to the possibility of lead substitution.…”

“…Previous computational work on acceptors in the all-inorganic lead halide perovskites employed semilocal functionals and did not take spin–orbit coupling (SOC) into account. ,, Though the resulting band gap is close to the correct value with such an approach due to a cancelation of errors, multiple works have found that the band-edge energies predicted by semilocal functionals are incorrect across the lead halide perovskite family, and that a hybrid functional and spin–orbit coupling together are required to calculate correct formation energies of charged defects and impurities in these materials. ,,− Computational studies employing only semilocal functionals are therefore unreliable. Moreover, previous work has only taken into account a limited set of possible acceptor dopants.…”