Figure 2: Electrical and cross-sectional characterization of the device.
From: Real-space observation of unbalanced charge distribution inside a perovskite-sensitized solar cell
(a) Current density-voltage (J-V) curve and device parameters of the sample. (b) AFM topography and (c) phase contrast images of the FIB-polished area. Within the mesoporous layer, we measured a root mean square surface roughness of 2.6 nm, indicating partially empty pores. Peak-to-peak heights correspond to the z-scale of the image. (d) Based on both images, we were able to define the material interfaces of the perovskite solar cell (white lines). (e) KPFM CPD map of the same area shown in b and c recorded under short-circuit conditions. For clarity, we have indicated interfaces with white lines. During KPFM mapping, the illumination of the solar cell was switched on (centre). (f) SEM micrograph of a FIB polished area. The perovskite capping layer varies in thickness from 0 to 200 nm. Furthermore, perovskite crystals were observed on top of the mesoporous TiO2 layer. The SEM image was recorded at a different position of the sample than KPFM to avoid SEM induced contaminations. (g) Energy level diagram of the device layer structure.
