Enhancing charge extraction in inverted perovskite solar cells contacts ultrathin graphene:fullerene composite interlayers

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 11; no. 24; pp. 12866 - 12875
• Main Authors: Zanetta, Andrea, Bulfaro, Isabella, Faini, Fabiola, Manzi, Matteo, Pica, Giovanni, De Bastiani, Michele, Bellani, Sebastiano, Zappia, Marilena Isabella, Bianca, Gabriele, Gabatel, Luca, Panda, Jaya-Kumar, Del Rio Castillo, Antonio Esaú, Prato, Mirko, Lauciello, Simone, Bonaccorso, Francesco, Grancini, Giulia
• Format: Journal Article
• Published: 20.06.2023
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d2ta07512a

Improving the perovskite/electron-transporting layer (ETL) interface is a crucial task to boost the performance of perovskite solar cells (PSCs). This is utterly fundamental in an inverted (p-i-n) configuration using fullerene-based ETLs. Here, we propose a scalable strategy to improve fullerene-based ETLs by incorporating high-quality few-layer graphene flakes (GFs), industrially produced through wet-jet milling exfoliation of graphite, into phenyl-C61-butyric acid methyl ester (PCBM). Our new composite ETL (GF:PCBM) can be processed into an ultrathin (∼10 nm), pinhole-free film atop the perovskite. We find that the presence of GFs in the PCBM matrix reduces defect-mediated recombination, while creating preferential paths for the extraction of electrons towards the current collector. The use of our GF-based composite ETL resulted in a significant enhancement in the open circuit voltage and fill factor of triple cation-based inverted PSCs, boosting the power conversion efficiency from ∼19% up to 20.8% upon the incorporation of GFs into the ETL. Improving the perovskite/electron-transporting layer (ETL) interface is a crucial task to boost the performance of perovskite solar cells (PSCs).