New generation hole transporting materials for Perovskite solar cells: Amide-based small-molecules with nonconjugated backbones

Journal article

State-of-the-art perovskite-based solar cells employ expensive, organic hole transporting materials (HTMs) such as Spiro-OMeTAD that, in turn, limits the commercialization of this promising technology. Herein an HTM (EDOT-Amide-TPA) is reported in which a functional amide-based backbone is introduced, which allows this material to be synthesized in a simple condensation reaction with an estimated cost of <$5 g−1. When employed in perovskite solar cells, EDOT-Amide-TPA demonstrates stabilized power conversion efficiencies up to 20.0% and reproducibly outperforms Spiro-OMeTAD in direct comparisons. Time resolved microwave conductivity measurements indicate that the observed improvement originates from a faster hole injection rate from the perovskite to EDOT-Amide-TPA. Additionally, the devices exhibit an improved lifetime, which is assigned to the coordination of the amide bond to the Li-additive, offering a novel strategy to hamper the migration of additives. It is shown that, despite the lack of a conjugated backbone, the amide-based HTM can outperform state-of-the-art HTMs at a fraction of the cost, thereby providing a novel set of design strategies to develop new, low-cost HTMs.

Authors: Petrus, M; Schutt, K; Sirtl, M; Hutter, E; Closs, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Advanced Energy Materials
• Volume: 8
• Issue: 32
• Article number: 1801605
• Publication date: 2018-10-08
• Acceptance date: 2018-09-12
• DOI: 10.1002/aenm.201801605
• EISSN: 1614-6840
• ISSN: 1614-6832
• Language: English
• Keywords: amides; hole transporting materials; low-cost; perovskites; solar cells