Fig. 1

Plan-view images of a device, using secondary electron (SE) contrast (left) and EBIC measurements (right). In all images, the TiO₂/perovskite/PTAA (polytriarylamine) layers are present. The changes are only in the presence or absence of the electrodes to the selective contacts, FTO or Au. a The edges of the Au pad and FTO are indicated for clarity. The apparent brighter layer close to the Au edge is an artifact of the scan parallel to an interface where charge extraction occurs. The areas that are shown in c (turned 90° clockwise) and d are indicated as blue squares. b Illustration of the device showing the edges of the FTO and Au electrodes (c) Expanded SE (left) and EBIC (right) images at the Au pad edge of the device, which is rotated by 90 degrees with respect to a. d Expanded SE (left) and EBIC (right) images at the FTO edge of the device. Owing to coverage by multiple layers, the FTO edge cannot be resolved in the SE image. Using EBIC contrast, the FTO edge can be located clearly