Electronic Properties of {111} Twin Boundaries in a Mixed-Ion Lead Halide Perovskite Solar Absorber

TY - JOUR

T1 - Electronic Properties of {111} Twin Boundaries in a Mixed-Ion Lead Halide Perovskite Solar Absorber

AU - McKenna, Keith P.

N1 - © 2018 American Chemical Society. ACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

PY - 2018/11/9

Y1 - 2018/11/9

N2 - We present first-principles theoretical predictions of the electronic properties of {111} twin boundaries in pure formamidinium lead iodide (FAPI) as well as a mixed-ion lead halide perovskite containing formamidinium, Cs, I, and Br. We find that the {111} twin boundary is extremely stable in pure FAPI but introduces no electron or hole trapping states and presents relatively small barriers (<100 meV) to transport of electrons and holes, suggesting that they are relatively benign for solar cell performance. However, in the mixed-ion perovskite, twin boundaries serve as a nucleation site for formation of an I- and Cs-rich secondary phase. The reduced band gap in this segregated phase leads to hole trapping and is likely to enhance electron–hole recombination and lead to reduced open-circuit voltage in solar cell devices. These results highlight the role of twin defects as nucleation sites for secondary phases, which can be extremely detrimental to solar cell performance.

AB - We present first-principles theoretical predictions of the electronic properties of {111} twin boundaries in pure formamidinium lead iodide (FAPI) as well as a mixed-ion lead halide perovskite containing formamidinium, Cs, I, and Br. We find that the {111} twin boundary is extremely stable in pure FAPI but introduces no electron or hole trapping states and presents relatively small barriers (<100 meV) to transport of electrons and holes, suggesting that they are relatively benign for solar cell performance. However, in the mixed-ion perovskite, twin boundaries serve as a nucleation site for formation of an I- and Cs-rich secondary phase. The reduced band gap in this segregated phase leads to hole trapping and is likely to enhance electron–hole recombination and lead to reduced open-circuit voltage in solar cell devices. These results highlight the role of twin defects as nucleation sites for secondary phases, which can be extremely detrimental to solar cell performance.

UR - http://www.scopus.com/inward/record.url?scp=85054608716&partnerID=8YFLogxK

U2 - 10.1021/acsenergylett.8b01700

DO - 10.1021/acsenergylett.8b01700

M3 - Article

SN - 2380-8195

VL - 3

SP - 2663

EP - 2668

JO - ACS Energy Letters

JF - ACS Energy Letters

IS - 11

ER -