Issue 66, 2020

Potassium iodide reduces the stability of triple-cation perovskite solar cells

Abstract

The addition of alkali metal halides to hybrid perovskite materials can significantly impact their crystallisation and hence their performance when used in solar cell devices. Previous work on the use of potassium iodide (KI) in active layers to passivate defects in triple-cation mixed-halide perovskites has been shown to enhance their luminescence efficiency and reduce current–voltage hysteresis. However, the operational stability of KI passivated perovskite solar cells under ambient conditions remains largely unexplored. By investigating perovskite solar cell performance with SnO2 or TiO2 electron transport layers (ETL), we propose that defect passivation using KI is highly sensitive to the composition of the perovskite–ETL interface. We reconfirm findings from previous reports that KI preferentially interacts with bromide ions in mixed-halide perovskites, and – at concentrations >5 mol% in the precursor solution – modifies the primary absorber composition as well as leading to the phase segregation of an undesirable secondary non-perovskite phase (KBr) at high KI concentration. Importantly, by studying both material and device stability under continuous illumination and bias under ambient/high-humidity conditions, we show that this secondary phase becomes a favourable degradation product, and that devices incorporating KI have reduced stability.

Graphical abstract: Potassium iodide reduces the stability of triple-cation perovskite solar cells

Supplementary files

Article information

Article type
Paper
Submitted
18 Aug 2020
Accepted
29 Oct 2020
First published
06 Nov 2020
This article is Open Access
Creative Commons BY license

RSC Adv., 2020,10, 40341-40350

Potassium iodide reduces the stability of triple-cation perovskite solar cells

T. I. Alanazi, O. S. Game, J. A. Smith, R. C. Kilbride, C. Greenland, R. Jayaprakash, K. Georgiou, N. J. Terrill and D. G. Lidzey, RSC Adv., 2020, 10, 40341 DOI: 10.1039/D0RA07107B

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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