Fig. 1: Nanoscale mechanical behavior of perovskite film surface and grain boundaries.
From: Perovskite solar cells with enhanced thermal fatigue resistance under extreme temperature cycling
a A sketch demonstrating the thermal behavior of perovskite polycrystalline structures with (iv) and without poly(LA) (i-iii) at the grain boundaries. b Thermal polymerization of LA and its multifunctional role at grain boundaries, facilitating defect passivation (1) and hydrogen bonding interactions (2) between polymer chains. c A sketch for the working mechanism of the surface-mapping tip-based nano-mechanical analysis technique. Numbers 1 and 2 indicate the perovskite grains and the poly(LA)-rich grain boundaries, respectively. d Adhesion forces were obtained from the perovskite surface at the HTL contact region using a tip-based nanomechanical surface-mapping technique, alongside topographical imaging. The values shown in the yellow boxes are the average adhesion forces extracted from each corresponding image. The white scale bar corresponds to 400 nm. Identical color scales are used for all samples within each row.
