Structure-Property Relationships in 2D Ruddlesden-Popper Sn- and Pb-based Iodide Perovskites
Nourdine Zibouche a
a Department of Chemistry, University of Bath, Claverton Down, University of Bath, Bath,UK, BA2 7AY, United Kingdom
Online Conference
Proceedings of Internet Conference on Theory and Computation of Halide Perovskites (ComPer)
Online, Spain, 2020 September 8th - 9th
Organizers: Giacomo Giorgi and Linn Leppert
Invited Speaker, Nourdine Zibouche, presentation 030
Publication date: 4th September 2020

In the fast-developing field of halide perovskite semiconductors, layered two-dimensional (2D) halide perovskites are receiving considerable attention for applications in photovoltaics, largely due to their versatile composition and superior, superior environment stability, and tunable optoelectronic properties[1]. However their power conversion efficiencies are much lower than their 3D analogues. Hence, further understanding of the structure–property relationships of these 2D materials is crucial for improving their photovoltaic performance. In this talk I will present the-findings of our recent work on 2D lead and tin Ruddlesden-Popper perovskites (BA2An-1BnI3n+1), with butylammonium (BA) as the organic spacer, A is either methylammonium (MA) or formamidinium (FA) cations, B represents Sn or Pb atoms, and n is the number of layers (n = 1, 2, 3, and 4)[2]. We show that the band gap progressively increases as the number of layers decreases in both Sn- and Pb-based materials. Through substituting MA by FA cations, the band gap slightly opens in the Sn systems and narrows in the Pb systems. The electron and hole carriers show small effective masses, which are lower than those of the corresponding 3D perovskites, suggesting high carrier mobilities. The structural distortion associated with the orientation of the MA or FA cations in the inorganic layers is found to be the driving force for the Rashba-induced spin-splittings in the systems with n > 1. The charge transfer kinetics in these 2D perovskites is found to be from smaller to higher number of layers n for electrons and oppositely for holes, in excellent agreement with experimental studies[3]. We also find that when interfaced with 3D analogues, the 2D perovskites could function as hole transport materials.

[1] L. Mao, C. C. Stoumpos, M. G. Kanatzidis; J. Am. Chem. Soc. 2019, 141, 3, 1171-1190

[2] N. Zibouche, M. S. Islam; ACS Appl. Mater. Interfaces, 12, 15328-15337

[3] J. Liu, et al.; J. Am. Chem. Soc. 2017, 139, 1432–1435.

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