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Tailoring metal halide perovskites through metal substitution: influence on photovoltaic and material properties

Abstract:
We present herein an experimental screening study that assesses how partially replacing Pb in methylammonium lead triiodide perovskite films with nine different alternative, divalent metal species, B = {Co, Cu, Fe, Mg, Mn, Ni, Sn, Sr, and Zn}, influences photovoltaic performance and optical properties. Our findings indicate the perovskite film is tolerant to most of the considered homovalent metal species with lead-cobalt compositions yielding the highest power conversion efficiencies when less than 6% of the Pb2+ ions are replaced. Through subsequent materials characterisation, we demonstrate for the first time that partially substituting Pb2+ at the B-sites of the perovskite lattice is not restricted to Group IV elements but is also possible with at least Co2+. Moreover, adjusting the molar ratio of Pb:Co in the mixed-metal perovskite affords new opportunities to tailor the material properties while maintaining stabilised device efficiencies above 16% in optimised solar cells. Specifically, crystallographic analysis reveals that Co2+ incorporates into the perovskite lattice and increasing its concentration can mediate a crystal structure transition from the cubic to tetragonal phase at room-temperature. Likewise, Co2+ substitution continually modifies the perovskite work function and band edge energies without either changing the band gap or electronically doping the intrinsic material. By leveraging this orthogonal dimension of electronic tunability, we achieve remarkably high open-circuit voltages up to 1.08 V with an inverted device architecture by shifting the perovskite into a more favourable energetic alignment with the PEDOT:PSS hole transport material.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1039/C6EE03201J

Authors


More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Condensed Matter Physics
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Condensed Matter Physics
Role:
Author



Publisher:
Royal Society of Chemistry
Journal:
Energy & Environmental Science More from this journal
Volume:
10
Pages:
236-246
Publication date:
2016-12-01
Acceptance date:
2016-11-18
DOI:
EISSN:
1873-6785
ISSN:
0360-5442


Pubs id:
pubs:664942
UUID:
uuid:2402a54a-054d-4266-8976-48ab6101d606
Local pid:
pubs:664942
Source identifiers:
664942
Deposit date:
2016-12-12

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