Photovoltaics: Moisture and Oxygen Enhance Conductivity of LiTFSI‐Doped Spiro‐MeOTAD Hole Transport Layer in Perovskite Solar Cells (Adv. Mater. Interfaces 13/2016)

As demonstrated by Yabing Qi and co-workers in Okinawa Institute of Science and Technology Graduate University in article 1600117, mercury drop electrode current-voltage measurements reveal that moisture in ambient air causes Li-bis(trifluoromethanesulfonyl)-imide dopants to re-distribute across spiro-MeOTAD hole transport layer in perovskite solar cells, thereby significantly improving hole transport properties. These findings suggest that moisture-induced dopant redistribution is most likely the major cause responsible for the efficiency enhancement in perovskite solar cells when exposed to ambient air for several hours after fabrication, a common practice in the field.