Anti-Oxidizing Perovskite Layer Formation via an Addition of Radical Polymers and its Photovoltaic Cells
Koki Suwa a, Kenichi Oyaizu a, Hiroshi Segawa b, Hiroyuki Nishide a
a Waseda University, Department of Applied Chemistry and Research Institute for Science and Engineering, Japan, 169-8555, Japón, Shinjuku City, Japan
b Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Japan, Japan
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Roma, Italy, 2020 May 12th - 14th
Organizers: Prashant Kamat, Filippo De Angelis and Aldo Di Carlo
Poster, Koki Suwa, 222
Publication date: 6th February 2020

Low durability of perovskite solar cells derived from an oxygen-triggered degradation of the perovskite compounds is one of the problematic issues. Superoxide anion radical (O2) generated by excited electrons at the surface of perovskite crystals reacts with perovskite compounds itself to yield methylamine, lead(Ⅱ) iodide, and so on [1]. Trapping the superoxide anion radical is an effective method to enhance the durability of the cells.

A small amount addition of radical-bearing redox-active polymers [2-3] during organo-lead halide perovskite layer formation enhanced durability of both the photovoltaic organo-lead halide perovskite layer and its solar cell even exposure to ambient air or oxygen. The radical polymers acted as an eliminating agent of the superoxide anion radical. Especially, the radical polymers-containing perovskite layer formed upon a planar tin oxide (SnO2) under layer showed larger eliminating effects against O2 than the cells upon a conventional mesoporous titanium dioxide (m-TiO2) under layer. The smooth charge-transport from the perovskite layer to m-TiO2 electron-transporting layer due to the large contact area might contribute to the suppression of charge-injection to oxygen and oxygen-triggered decomposition of the perovskite layer.

The polymers also contributed as an effective scaffold to form high quality mixed-cation perovskite crystals with a larger grain size and less grain boundaries. Photovoltaic current was not reduced in the presence of radical polymers in the perovskite layer because of a carrier conductivity of them.

This work was partially supported by NEDO project, Japan.

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