Ionic Liquid Additive‐Assisted Highly Efficient Electron Transport Layer‐Free Perovskite Solar Cells

Perovskite solar cells (PSCs) have achieved unprecedented power conversion efficiency improvements, and further development is stepping to industrialization. In terms of industrial manufacturing, simplifying the solar cell structure is critical in both fabrication process design and cost control. Due to the bipolar charge transport nature of perovskites, the elimination of the charge carrier transport layer is possible. Herein, EMIMPF6 ionic liquid is incorporated into the perovskite film to modulate the energy‐level alignment and the charge transfer kinetics, demonstrating a high‐performance electron transport layer‐free (ETL‐free) PSC. The integrated EMIMPF6 assisted the internal charge collection and favored the interfacial charge transfer from perovskite to FTO substrate, contributing to the high performance of ETL‐free PSCs. The ETL‐free PSCs showed a conversion efficiency of 16.2%, which is comparable with its conventional counterpart. This work provides a solution to simplify the PSC structure and would have an impact on designing a scalable manufacturing process for PSCs. An electron transport layer‐free (ETL‐free) perovskite solar cell is demonstrated by the addition of EMIMPF6 ionic liquid within the perovskite layer. The integrated EMIMPF6 assisted the internal charge collection and favored the interfacial charge transfer from perovskite to FTO glass substrate, contributing to the high performance of the ETL‐free device.