Hydrogen bonding in perovskite solar cells

The perovskite research community have leveraged ionic and covalent bonding to engineer efficient optoelectronic devices. These interactions are large in magnitude, with their effects prominently manifesting in films and devices. Yet, it is emerging that the subtle and directional effects of hydrogen bonding also greatly impact device performance and stability. We have reviewed the impacts of hydrogen bonding in the perovskite literature and found that its influence has been revealed to different extents across the functional layers and their interfaces. Inter- and intramolecular hydrogen bonding between alkylammonium donors and the halides affects crystal structure, directly impacting both the band structure and stability of the perovskite phase. More subtle effects have been revealed on charge transport, ion migration, mechanical performance, etc. We summarize the progress in the application, understanding, characterization, and modeling of hydrogen bonding as applied to perovskites and their devices.