Chemical passivation serves as a highly effective strategy
for
mitigating defects to obtain efficient and stable perovskite solar
cells. However, concerns about the stability and environmental-friendliness
of molecular modulators have emerged with regard to the passivation
effect. In this article, we introduce a judicious hydrogen bond network
(HBN) composed of imidazole (ImA) and salicylic acid (SA) to address
this issue. The ImA-SA HBN features multiple functional groups (amino
and carboxyl) that simultaneously passivate various defects, including
I– vacancies and uncoordinated Pb2+ ions
located at grain boundaries and surfaces of the perovskite films.
Remarkably, the ImA-SA HBN effectively bridges perovskite grains and
interfaces between the perovskite films and hole transport materials,
which enhances the transport of photogenerated carriers. Moreover,
cyclic ImA-SA, characterized by steric hindrance, inhibits ion migration
derived from grain boundaries of the perovskite films. Consequently,
the efficiency of the champion device processed in fully ambient air
exceeded 21% and did not decline obviously after 3380 h of storage
in the air environment (20 ± 5 °C, 30 ± 5% RH, and
without encapsulation). This work offers a promising approach to diminishing
the defects in perovskite grain boundaries and surfaces, enhancing
optoelectronic properties and facilitating the creation of efficient
and stable perovskite solar cells processed in fully ambient air.