A Theoretical Tour of Metal-Halide Perovskites Defects Chemistry: from Lead to Tin
Daniele Meggiolaro a
a Istituto di Scienze e Tecnologie Chimiche "Giulio Natta" (SCITEC), Consiglio Nazionale delle Ricerche
Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS23 & Sustainable Technology Forum València (STECH23) (MATSUS23)
#DeModeP23 - Characterisation and modeling of devices
València, Spain, 2023 March 6th - 10th
Organizers: Enrique Hernández Balaguera and Alison Walker
Invited Speaker, Daniele Meggiolaro, presentation 376
Publication date: 22nd December 2022

Lead halide perovskites have revolutionized the scenario of photovoltaics due to their excellent and tunable optoelectronic properties leading to solar cell efficiencies comparable to traditional high-quality silicon materials.[1] Issues concerning the presence of lead, however, have led researchers to find less toxic candidates possibly replacing lead in the perovskite, particularly tin. The performance of tin halide perovskites, however, is strongly limited by an enhanced self p-doping and the easy oxidation of Sn(II) to Sn(IV).[2] To guide the development of lead-free materials withenhanced efficiency and stability, a deep understanding of the defect chemistry and photophysics of these materials is needed. Ab-initio simulations represent a powerful tool to investigate defect properties and processes at the atomistic level. In this presentation a theoretical tour of the defect activity in lead- and tin-based perovskites is provided. We will show how DFT calculations may be applied to study defects in materials, the useful quantities obtained by simulations and the best practices in the case of metal halide perovskites. Hence, the trend in defect activity by moving from lead to tin will be discussed.[3] The nature of most abundant defects, their trapping activity and the impact on the doping of the materials will be illustrated. Defect driven mechanisms possibly activating the degradation of these perovskites will be discussed based on the defect analysis.[4] Furthermore, the effects of quantum confinement on the optoelectronic features and defect properties moving to low dimensional 2D perovskites will be showed, also in relation to emission features emerging in these quantum confined systems, such as broad emission, whose origin is hotly debated.[5] This work aims to provide a unified picture of defect chemistry of metal halide perovskites with emphasis on the factors governing the stability and the efficiency of these materials. It also aims to stimulate the community to a synergistic use of computer simulations to support the design of more
efficient and long-term stable devices.

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