Fig. 5
Charge transport and device performance with different degrees of orientation. Pre-crystallization annealed film with strong vertical orientation indicated by GIWAXS in b provides direct pathway for electron and hole extraction in a, while in post-crystallization annealed film with partial random orientation in d, charge carriers need to hop through electrically insulating organic ligands to reach electron transporting layer (ETL) and hole transporting layer (HTL), which hinders charge extraction in c. The percentage of oriented crystallites in the perovskite film is defined as fori. Performance of solar cell with pre-crystallization annealing method (red and black lines) is significantly higher than that of post-crystallization annealing method (green and blue lines) in e
