Crystal chemical insights on lead iodide perovskite doping from revised effective radii of metal ions

TL;DR

This study introduces revised effective radii for metal ions in iodine environments, clarifies their lattice positions in lead iodide perovskites, and offers a theoretical framework to enhance doping strategies for improved optoelectronic properties.

Contribution

It provides a systematic analysis of metal ion lattice positions in lead iodide perovskites using revised effective radii, aiding in rational doping strategies.

Findings

Effective size, electronegativity, and ion softness are key parameters for doping feasibility.

Revised effective radii help predict metal ion incorporation in perovskite structures.

Guidelines for selecting suitable metal dopants to optimize perovskite properties.

Abstract

Over the last few years of the heyday of hybrid halide perovskites, so many metal cations additives have been tested to improve their optoelectronic properties that it is already difficult to find an element that has not yet been tried. In general, the variety of these approaches is united under the name "doping", however, there is currently no clear understanding of the mechanisms of the influence of the metal ion additives on the properties of the lead halide perovskite materials. For many ions there is even no consensus on the most fundamental questions: what lattice position does a given ion occupy and is it incorporated in the structure at all? Here, we derived a system of effective radii of different metal ions in the iodine environment for the set of iodide compounds and reveal their crystal chemical role in the APbI3 perovskites. We analysed the possible lattice positions for 40 most common monovalent, divalent, and trivalent metals to reveal whether they could successfully enter into the perovskite structures. We show that, at most, three parameters - effective size, electronegativity and the softness of metal ions are the main ones for crystal chemical analysis of the possibility of metal doping of hybrid halide perovskites. Our results provide a useful theoretical guidance to rationalize and improve current doping strategies of hybrid halide perovskites with metal ions.