A Mixed PC61BM‐COi8DFIC Based Electron Transport Material for Inverted High‐performance Perovskite Solar Cells

Introducing fullerene (PC₆₁B) into a non-fullerene (COi8DFIC) acceptor suppresses its high crystallization nature, showed good inter-molecule mixing, reduced intermolecular distances and decent morphology, resulting in excellent charge carrier transport properties and benefits from the order phase of fullerene.

Abstract

This study reports a blend of [6, 6]-phenyl-C61-butyric acid methyl ester (PC₆₁BM) and COi8DFIC non-fullerene acceptor (NFA) as an electron transport layer (ETL) in perovskite solar cells (PSCs). This mixed small-molecule ETL showed good inter-molecule mixing, reduced intermolecular distances and decent morphology, resulting in excellent charge carrier transport properties. Morever, charge carrier extraction and transport at the perovskite/ETL interface was optimized by reducing surface traps and defects due to the passivation ability of various terminal groups from the COi8DFIC molecule. A high power conversion efficiency (PCE) of 19.12 % was achieved by taking advantage of benefits from both molecules, showing much better performance than the invidual PC₆₁BM or COi8DFIC (7.13% for using the NFA only). Moreover, the storage and ambient stabilities of the mixed ETL-based PSCs increased dramatically compared to control devices.

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