Solvent engineering of the electron transport layer using 1,8-diiodooctane for improving the performance of perovskite solar cells

•Perovskite solar cells were improved by solvent engineering using 1,8-diiodooctane.•The power conversion efficiency was improved by 14.8%.•The short-circuit current, fill factor, and open-circuit voltage were improved.•1,8-Diiodooctane improved the morphology of the electron transport layer.

In this work, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) was improved by 14.8% (from 11.09% to 12.73%) by using 1,8-diiodooctane (DIO) as a solvent additive during the deposition of phenyl-C61-butyric acid methyl ester (PCBM) layers. The primary reasons for the PCE improvement are the simultaneous increases in the short-circuit current density, fill factor, and open-circuit voltage. The incorporation of DIO improves the morphology of the electron transport layer (PCBM), which plays an important role in charge dissociation, transportation, and collection. Our results indicate that engineering the morphology of the electron transport layer is a simple and effective method for developing high-performance PSCs.

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