The poor interfacial contact and imperfections between
the charge
transport layer and perovskite film often result in carrier recombination,
inefficient charge collection, and inferior stability of perovskite
solar cells (PSCs). Therefore, interface engineering is quite crucial
to achieve high-performance and stable PSCs. Here, we introduced a
cinnamate-functionalized cellulose nanocrystals (Cin-CNCs) interfacial
layer between SnO2 and perovskite active layer for enhancing
carrier transport ability and crystal growth of perovskite, meanwhile
endowing additional functional of long-term device stability against
ultraviolet light. The enhancement of interfacial contact between
SnO2 and perovskite layer and cascade energy alignment
are realized, which is beneficial for obtaining the desirable perovskite
film morphology, passivating the interfacial defects, and restraining
charge recombination in the SnO2/perovskite interface.
An efficiency as high as 23.18%, with an open-circuit voltage of 1.15
V and a significantly enhanced fill factor of 81.07%, is achieved.
In addition, the unencapsulated PSCs maintain 75% of the initial PCE
after aging for over 1500 h under 25 °C and 30% relative humidity,
with better light-soaking stability. These results exhibit the vital
role for Cin-CNCs in interfacial modification and constructing high-performance
perovskite solar cells.