title: Carbon nanotube/polymer composites as a highly stable hole collection layer in perovskite solar cells.
abstract: Organic-inorganic perovskite solar cells have recently emerged at the forefront of photovoltaics research. Power conversion efficiencies have experienced an unprecedented increase to reported values exceeding 19% within just four years. With the focus mainly on efficiency, the aspect of stability has so far not been thoroughly addressed. In this paper, we identify thermal stability as a fundamental weak point of perovskite solar cells, and demonstrate an elegant approach to mitigating thermal degradation by replacing the organic hole transport material with polymer-functionalized single-walled carbon nanotubes (SWNTs) embedded in an insulating polymer matrix. With this composite structure, we achieve JV scanned power-conversion efficiencies of up to 15.3% with an average efficiency of 10 ± 2%. Moreover, we observe strong retardation in thermal degradation as compared to cells employing state-of-the-art organic hole-transporting materials. In addition, the resistance to water ingress is remarkably enhanced. These are critical developments for achieving long-term stability of high-efficiency perovskite solar cells.
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory , Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: Severin N
authors.initials: SN
authors.lastname: Habisreutinger
authors.forename: Tomas
authors.initials: T
authors.lastname: Leijtens
authors.forename: Giles E
authors.initials: GE
authors.lastname: Eperon
authors.forename: Samuel D
authors.initials: SD
authors.lastname: Stranks
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Nicholas
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Snaith
keywords: Photovoltaics; hole-transport materials; perovskite solar cells; polymer functionalization; single-walled carbon nanotubes; stability