  The use of antisolvents during the fabrication of solution-processed lead
halide perovskite layers is increasingly common. Usually, the antisolvent is
applied by pipetting during the spin-coating process, which often irreversibly
alters the composition of the perovskite layer, resulting in the formation of
PbI2 at the surface and bulk of the perovskite layer. Here, we demonstrate that
by applying the antisolvent via carrier-gas free spraying, the stoichiometry of
the perovskite layer is far better preserved. Consequently, the photovoltaic
performance of triple cation photovoltaic devices fabricated in an inverted
architecture is enhanced, mainly due to an increase in the open-circuit
voltage. By exploring different volumes of antisolvent, we show that spraying
as little as 60 uL results in devices with power conversion efficiencies as
high as 21%. Moreover, solar cells with sprayed antisolvent are more stable
than those fabricated by pipetting the antisolvent.
