  Demonstration of high-efficiency large area cells with excellent stability is
an important requirement towards commercialization of perovskite solar cells
(PSC). With reports of high-quality perovskite grains, it is evident that the
performance of such large area cells will be strongly influenced by phenomena
like carrier recombination and ion migration at grain boundaries (GBs). Here,
we develop a modeling framework to address performance limitation due to GBs in
large area PSCs. Through detailed numerical simulations, we show that
photo-carrier recombination has a non-trivial dependence on the orientation of
GBs. Interestingly, we find that ions at GBs lead to significant performance
recovery through field effect passivation, which is influenced by critical
parameters like density and polarity of ions, and the location of GB. These
results have interesting implications towards long-term stability and hence are
relevant for the performance optimization of large area polycrystalline based
thin film solar cells such as PSCs, CIGS, CZTS, etc.
