Correction to: Nature Reviews Materials https://doi.org/10.1038/s41578-022-00431-2, published online 30 March 2022.

In the original version of this article, the current–voltage curves in the middle panel of Figure 5 were shown in the wrong order, and with wrong colours. The curve on the left-hand side should have appeared on the right-hand side and in red. The curve on the right-hand side should have appeared on the left-hand side and in blue. The figure has been corrected both in the PDF and in the HTML versions of the article.