Accumulation of Deep Traps at Grain Boundaries in Halide Perovskites

Ji Sang Park, Joaquín Calbo, Young Kwang Jung, Lucy D. Whalley, Aron Walsh

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102 Scopus citations


The behavior of grain boundaries in polycrystalline halide perovskite solar cells remains poorly understood. Whereas theoretical studies indicate that grain boundaries are not active for electron-hole recombination, there have been observations of higher nonradiative recombination rates involving these extended defects. We find that iodine interstitial defects, which have been established as a recombination center in bulk crystals, tend to segregate at planar defects in CsPbI3. First-principles calculations show that enhanced structural relaxation of the defects at grain boundaries results in increased stability (higher concentration) and deeper trap states (faster recombination). We show how the grain boundary can be partly passivated by halide mixing or extrinsic doping, which replaces or suppresses the formation of trap states close to the grain boundaries.

Original languageEnglish
Pages (from-to)1321-1327
Number of pages7
JournalACS Energy Letters
Issue number6
StatePublished - 14 Jun 2019

Bibliographical note

Funding Information:
Via our membership of the UK’s HPC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work used the ARCHER UK National Supercomputing Service ( We are grateful to the UK Materials and Molecular Modelling Hub for computational resources, which is partially funded by EPSRC (EP/P020194/ 1). This work was supported by supercomputer time awarded through PRACE on the Swiss National Supercomputing Center (CSCS) under Project pr51. J.P. thanks the Royal Society for a Shooter Fellowship. J.C. acknowledges the Generalitat Valenciana for the APOSTD/2017/081 fellowship. L.W. is funded through the EPSRC (EP/L01551X/1). This work at Yonsei was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2018R1C1B6008728)

Publisher Copyright:
© 2019 American Chemical Society.


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