Critical Assessment of the Use of Excess Lead Iodide in Lead Halide Perovskite Solar Cells.
Publication Date
2020-08-20Journal Title
J Phys Chem Lett
ISSN
1948-7185
Publisher
American Chemical Society (ACS)
Volume
11
Issue
16
Pages
6505-6512
Language
eng
Type
Article
This Version
VoR
Physical Medium
Print-Electronic
Metadata
Show full item recordCitation
Roose, B., Dey, K., Chiang, Y., Friend, R., & Stranks, S. (2020). Critical Assessment of the Use of Excess Lead Iodide in Lead Halide Perovskite Solar Cells.. J Phys Chem Lett, 11 (16), 6505-6512. https://doi.org/10.1021/acs.jpclett.0c01820
Abstract
It is common practice in the lead halide perovskite solar cell field to add a small molar excess of lead iodide (PbI2) to the precursor solution to increase the device performance. However, recent reports have shown that an excess of PbI2 can accelerate performance loss. In addition, PbI2 is photoactive (band gap ∼2.3 eV), which may lead to parasitic absorption losses in a solar cell. Here we show that devices using small quantities of excess PbI2 exhibit better device performance as compared with stoichiometric devices, both initially and for the duration of a stability test under operating conditions, primarily by enhancing the charge extraction. However, the photolysis of PbI2 negates the beneficial effect on charge extraction by leaving voids in the perovskite film and introduces trap states that are detrimental for device performance. We propose that although excess PbI2 provides a good template for enhanced performance, the community must continue to seek other additives or synthesis routes that fulfill the same beneficial role as excess PbI2, but without the photolysis that negates these beneficial effects under long-term device operation.
Relationships
Is supplemented by: https://doi.org/10.17863/CAM.55401
Sponsorship
Royal Society (UF150033)
Engineering and Physical Sciences Research Council (EP/R023980/1)
Engineering and Physical Sciences Research Council (EP/M005143/1)
Royal Society (NF170520)
EPSRC (EP/T02030X/1)
European Research Council (756962)
Embargo Lift Date
2100-01-01
Identifiers
External DOI: https://doi.org/10.1021/acs.jpclett.0c01820
This record's URL: https://www.repository.cam.ac.uk/handle/1810/308343
Rights
Attribution 4.0 International (CC BY)
Licence URL: http://creativecommons.org/licenses/by/4.0/
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