Correction: Corrigendum: Enhanced electron extraction using SnO2 for high-efficiency planar-structure HC(NH2)2PbI3-based perovskite solar cells

In the original version of this Article, a recent publication was inadvertently omitted.This has now been included and the relevant sentences have been updated to 'Recently, it was also used in perovskite solar cells in order to increase the efficiency and to reduce the hysteresis [23][24][25][26][27] .During the final preparation of this Article, ref. 28 was published, reporting planar perovskite solar cells with an average PCE around 18.5% and a mild hysteresis.' 28.