Suppressed Halide Ion Migration in 2D Lead Halide Perovskites
Junsang Cho a, Prashant Kamat a
a Radiation Laboratory, University of Notre Dame, US, United States
Proceedings of Online International Conference on Hybrid and Organic Photovoltaics (OnlineHOPV20)
Online, Spain, 2020 May 26th - 29th
Organizers: Tracey Clarke, James Durrant, Annamaria Petrozza and Trystan Watson
Poster, Junsang Cho, 141
Publication date: 22nd May 2020

Two-dimensional (2D) lead halide perovskites represent an emerging class of materials given their tunable
optoelectronic properties and long-term stability in perovskite solar cells. In order to assess the halide ion mobility, we have
tracked the changes in the bromide and iodide composition in physically paired 2D lead halide perovskite films of different layer
numbers (n = 10−1). These low-dimensional perovskites suppressed halide ion migration as a result of their intercalated spacer
ligands and their strong van der Waals interactions. The rate constants for halide exchange of low dimensionality perovskites
follow the Arrhenius relationship with thermal activation energy ranging from 58 kJ/mol (n = 10) to 72 kJ/mol (n = 1). The
suppression of halide ion mobility (and diffusion coefficient) with modulating perovskite layer number (n) provides further insight
into the role of 2D perovskites in improving the performance of photovoltaic devices.

The research described herein is supported by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of
Basic Energy Sciences of the U.S. Department of Energy, through award DE-FC02-04ER15533. This is contribution
number NDRL No. 5277 from the Notre Dame Radiation Laboratory.

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