posted on 2021-12-27, 13:34authored byBrandon Dunham, Drake Bal, Yooyeon Jo, Yuxi Wang, Christos Dimitrakopoulos
The
poor environmental stability of hybrid perovskite solar cells
(PSCs) remains one of the leading obstacles to their commercialization.
Herein, we develop and use, for the first time, an orthogonal solvent-assisted
process to transfer sheets of monolayer chemical vapor deposited (CVD)
graphene onto the perovskite active layer without causing damage to
the perovskite layer. We show that at this location in a standard
methylammonium lead iodide PSC stack, the CVD graphene acts as a barrier
layer to improve stability by (i) preventing moisture ingress into
the perovskite layer and (ii) blocking the diffusion of silver ions
from the electrode to the perovskite layer. Upon exposure to humidity
for 1 week, unencapsulated devices with a graphene barrier retained
93% of their initial PCE, whereas those devices without a graphene
barrier retained only 46%. Similarly, after heat treatment, unencapsulated
devices with a graphene barrier showed no decrease in PCE, whereas
those without a graphene barrier decreased to ∼75% of their
initial PCE. CVD graphene is shown to be a prime candidate for improving
the environmental stability of PSCs.