Optimal Interfacial Band Bending Achieved by Fine Energy Level Tuning in Mixed-Halide Perovskite Solar Cells

Matyas Daboczi; Sinclair R. Ratnasingham; Lokeshwari Mohan; Chenfeng Pu; Iain Hamilton; Yi-Chun Chin; Martyn A. McLachlan; Ji Seon Kim

doi:10.1021/acsenergylett.1c02044

Optimal Interfacial Band Bending Achieved by Fine Energy Level Tuning in Mixed-Halide Perovskite Solar Cells

Matyas Daboczi, Sinclair R. Ratnasingham, Lokeshwari Mohan, Chenfeng Pu, Iain Hamilton, Yi-Chun Chin, Martyn A. McLachlan, Ji Seon Kim

Physical Sciences and Engineering

Research output: Contribution to journal › Article › peer-review

27 Scopus citations

Abstract

Most highly efficient perovskite solar cells employ mixed iodide–bromide photoactive layers; however, understanding the beneficial effect of the low (5–15 mol %) bromide content is incomplete. Here, a series of MAPb(I1–xBrx)3 perovskite layers are investigated to understand the origin of the high peak power conversion efficiency (19.2%) observed at small bromide content (0.10 ≤ x ≤ 0.125). For the x = 0.125 perovskite, 200 meV shallower energy levels are revealed, accompanied by a reduced density of trap states and stable tetragonal mixed-halide phase with compressed unit cell. In contrast, the higher bromide content samples (x > 0.125) show deeper energy levels, cubic perovskite crystal structure, and signs of halide segregation. Surface photovoltage measurements unveil an undesirable band bending at the hole transport layer/perovskite interface for MAPbI3 and x > 0.125 mixed-halide layers, which is eliminated for the x = 0.125 perovskite because of its shallower Fermi level, enabling enhanced device performance.

Original language	English (US)
Pages (from-to)	3970-3981
Number of pages	12
Journal	ACS Energy Letters
DOIs	https://doi.org/10.1021/acsenergylett.1c02044
State	Published - Oct 21 2021

Bibliographical note

KAUST Repository Item: Exported on 2021-10-25
Acknowledgements: The authors acknowledge the funding of UK Engineering and Physical Sciences Research Council (EPSRC) Plastic Electronics Doctoral Training Centre (EP/L016702/1) and KP Technology Ltd for EPSRC CASE studentships. This research was also supported by the UK EPSRC ATIP Programme Grant (EP/T028513/1) and the Global Research Laboratory Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2017K1A1A2 013153).

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title = "Optimal Interfacial Band Bending Achieved by Fine Energy Level Tuning in Mixed-Halide Perovskite Solar Cells",

abstract = "Most highly efficient perovskite solar cells employ mixed iodide–bromide photoactive layers; however, understanding the beneficial effect of the low (5–15 mol %) bromide content is incomplete. Here, a series of MAPb(I1–xBrx)3 perovskite layers are investigated to understand the origin of the high peak power conversion efficiency (19.2%) observed at small bromide content (0.10 ≤ x ≤ 0.125). For the x = 0.125 perovskite, 200 meV shallower energy levels are revealed, accompanied by a reduced density of trap states and stable tetragonal mixed-halide phase with compressed unit cell. In contrast, the higher bromide content samples (x > 0.125) show deeper energy levels, cubic perovskite crystal structure, and signs of halide segregation. Surface photovoltage measurements unveil an undesirable band bending at the hole transport layer/perovskite interface for MAPbI3 and x > 0.125 mixed-halide layers, which is eliminated for the x = 0.125 perovskite because of its shallower Fermi level, enabling enhanced device performance.",

author = "Matyas Daboczi and Ratnasingham, {Sinclair R.} and Lokeshwari Mohan and Chenfeng Pu and Iain Hamilton and Yi-Chun Chin and McLachlan, {Martyn A.} and Kim, {Ji Seon}",

note = "KAUST Repository Item: Exported on 2021-10-25 Acknowledgements: The authors acknowledge the funding of UK Engineering and Physical Sciences Research Council (EPSRC) Plastic Electronics Doctoral Training Centre (EP/L016702/1) and KP Technology Ltd for EPSRC CASE studentships. This research was also supported by the UK EPSRC ATIP Programme Grant (EP/T028513/1) and the Global Research Laboratory Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2017K1A1A2 013153).",

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T1 - Optimal Interfacial Band Bending Achieved by Fine Energy Level Tuning in Mixed-Halide Perovskite Solar Cells

AU - Daboczi, Matyas

AU - Ratnasingham, Sinclair R.

AU - Mohan, Lokeshwari

AU - Pu, Chenfeng

AU - Hamilton, Iain

AU - Chin, Yi-Chun

AU - McLachlan, Martyn A.

AU - Kim, Ji Seon

N1 - KAUST Repository Item: Exported on 2021-10-25 Acknowledgements: The authors acknowledge the funding of UK Engineering and Physical Sciences Research Council (EPSRC) Plastic Electronics Doctoral Training Centre (EP/L016702/1) and KP Technology Ltd for EPSRC CASE studentships. This research was also supported by the UK EPSRC ATIP Programme Grant (EP/T028513/1) and the Global Research Laboratory Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2017K1A1A2 013153).

PY - 2021/10/21

Y1 - 2021/10/21

N2 - Most highly efficient perovskite solar cells employ mixed iodide–bromide photoactive layers; however, understanding the beneficial effect of the low (5–15 mol %) bromide content is incomplete. Here, a series of MAPb(I1–xBrx)3 perovskite layers are investigated to understand the origin of the high peak power conversion efficiency (19.2%) observed at small bromide content (0.10 ≤ x ≤ 0.125). For the x = 0.125 perovskite, 200 meV shallower energy levels are revealed, accompanied by a reduced density of trap states and stable tetragonal mixed-halide phase with compressed unit cell. In contrast, the higher bromide content samples (x > 0.125) show deeper energy levels, cubic perovskite crystal structure, and signs of halide segregation. Surface photovoltage measurements unveil an undesirable band bending at the hole transport layer/perovskite interface for MAPbI3 and x > 0.125 mixed-halide layers, which is eliminated for the x = 0.125 perovskite because of its shallower Fermi level, enabling enhanced device performance.

AB - Most highly efficient perovskite solar cells employ mixed iodide–bromide photoactive layers; however, understanding the beneficial effect of the low (5–15 mol %) bromide content is incomplete. Here, a series of MAPb(I1–xBrx)3 perovskite layers are investigated to understand the origin of the high peak power conversion efficiency (19.2%) observed at small bromide content (0.10 ≤ x ≤ 0.125). For the x = 0.125 perovskite, 200 meV shallower energy levels are revealed, accompanied by a reduced density of trap states and stable tetragonal mixed-halide phase with compressed unit cell. In contrast, the higher bromide content samples (x > 0.125) show deeper energy levels, cubic perovskite crystal structure, and signs of halide segregation. Surface photovoltage measurements unveil an undesirable band bending at the hole transport layer/perovskite interface for MAPbI3 and x > 0.125 mixed-halide layers, which is eliminated for the x = 0.125 perovskite because of its shallower Fermi level, enabling enhanced device performance.

UR - http://hdl.handle.net/10754/672936

UR - https://pubs.acs.org/doi/10.1021/acsenergylett.1c02044

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SP - 3970

EP - 3981

JO - ACS Energy Letters

JF - ACS Energy Letters

ER -

Optimal Interfacial Band Bending Achieved by Fine Energy Level Tuning in Mixed-Halide Perovskite Solar Cells

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