Tantalum(V) Bromide

Nowicki, D. H.; Campbell, I. E.; Schumb, Walter C.; Brubaker, Carl H.

doi:10.1002/9780470132357.ch44

Cited by 4 publications

(1 citation statement)

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“…This indicates that there are other factors at play dictating the feasibility of incorporating an element in the perovskite environment, such as affinity for Br and a preferred bromide coordination environment. Both Ta and W, for instance, are known to create square pyramidal MBr 5 environments in their experimentally known bromide compounds, , leading to some amount of distortion in the MBr 6 octahedron relative to the PbBr 6 octahedron in the MA 8 Pb 7 MBr 24 lattice. This octahedral distortion further leads to changes in the perovskite electronic structure and creation of impurity levels.…”

Section: Resultsmentioning

confidence: 99%

Comprehensive Computational Study of Partial Lead Substitution in Methylammonium Lead Bromide

et al. 2019

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Impurities in semiconductors, for example, lead-based hybrid perovskites, have a major influence on their performance as photovoltaic (PV) light absorbers. While impurities could create harmful trap states that lead to nonradiative recombination of charge carriers and adversely affect PV efficiency, they could also potentially increase absorption via midgap energy levels that act as stepping stones for subgap photons or introduce charge carriers via doping. To unearth trends in impurity energy states, we use first principles density functional theory calculations to extensively study partial substitution of Pb in methylammonium lead bromide (MAPbBr3), a representative lead-halide perovskite. Investigation of the density of states and energy levels related to the transition of the substitutional defect from one charge state to another reveals that several elements create midgap energy states in MAPbBr3. We machine learned trends and design rules from the computational data and discovered that a few easily computed properties of the bromide compounds of any element can be used to predict the energetics and energy levels of the substitutional defect related to that element. The calculated Fermi level-dependent defect formation energies lead to the observation that substitution by transition metals, Zr, Hf, Nb, and Sc, and group V element Sb can shift the equilibrium Fermi level and change the perovskite conductivity, as determined by the dominant intrinsic point defects. Finally, metal-substituted MAPbBr3 compounds of Bi, Sc, Ni, and Zr were experimentally investigated, and while there was an improvement in the thin-film morphology and an enhancement in charge-carrier lifetimes, no clear evidence of subgap absorption features owing to the substituent being incorporated in the MAPbBr3 lattice could be seen.

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Section: Resultsmentioning

confidence: 99%