Fig. 2From: A Short Progress Report on High-Efficiency Perovskite Solar Cells a Crystal structure of a perovskite [22]. b Schematic diagram of general device [23]. c Cross-section scanning electron microscopy (SEM) images of a meso-superstructured perovskite solar cell (scale bar is 500 nm) [22]. d Cross-section SEM images of a normal planar perovskite solar cells with the presence of an HTL and an ETL [22]Back to article page