Nature Materials 16, 1209–1215 (2017); published online 13 November 2017; corrected after print 15 December 2017.

In the version of this Article originally published, the source of 'ZADN' stated in the Methods should have read 'obtained as free research samples from Guangzhou ChinaRay Optoelectronic Materials' instead of 'China-Ray'. This has now been corrected in the online versions of the Article.