Selecting suitable charge transport layers and suppressing non‐radiative recombination at interfaces with the absorber layer is vital for maximizing the efficiency of halide perovskite solar cells. In this study, high‐quality perovskite thin films and devices are fabricated with different fullerene‐based electron transport layers and different self‐assembled monolayers as hole transport layers. Then, a comparative study of a significant variety of different electrical, optical, and photoemission‐based characterization techniques is performed to quantify the properties of the solar cells, individual layers, and, importantly, the interfaces between them. In addition, the limitations and problems of the different measurements, the insights gained by combining different methods, and the different strategies for extracting information from the experimental raw data, are highlighted.

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