Unencapsulated organo-tin perovskite photovoltaics with high stability in ambient air using a semi-metal capped copper top electrode
Anjana Wijesekara a, Yisong Han b, David Walker b, Steven Huband b, Ross Hatton a
a Department of Chemistry, University of Warwick, CV4 7AL, Coventry, United Kingdom.
b Department of Physics, University of Warwick, CV47AL, Coventry, United Kingdom
Proceedings of Sustainable Metal-halide perovskites for photovoltaics, optoelectronics and photonics (Sus-MHP)
València, Spain, 2022 December 12th - 13th
Organizers: Teresa S. Ripolles and Hui-Seon Kim
Oral, Ross Hatton, presentation 011
Publication date: 15th November 2022

We report a remarkably effective approach to passivating the copper cathode in inverted organo-tin halide perovskite photovoltaics, based on capping the cathode with a thin layer of a semi-metal. Using this simple approach unencapsulated photovoltaic devices retain 70% of their peak power conversion efficiency after up to 100 hours testing under continuous one sun solar illumination in ambient air and under electrical load. The semi-metal layer is shown to block corrosion of the copper cathode by iodine gas formed when those parts of the perovskite layer not protected by the electrode degrade, which we have previously shown to be a major source of device degradation in air [1]. The semi-metal layer is also shown to sequester iodine gas by seeding its condensation on top of the device, reducing the likelihood that it will ingress laterally through the electron transport layer photo-catalysing the degradation of the perovskite and corroding the buried cathode interface. It is envisaged that this electrode-based approach to improving device stability can be combined with any of the recently reported chemical approaches to improving the intrinsic stability of organo-tin halide perovskites in air.

 

 

The authors would like to thank the Institute of Advanced Studies, University of Warwick for the award of an Early Career Research Fellowship to Anjana Wijesekara.

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