  Fully printed flexible perovskite solar cells (f-PSCs) show great potential
for the commercialization of perovskite photovoltaics owing to their
compatibility with high-throughput roll-to-roll (R2R) production. However, the
challenge remains in the deficiency in controlling interfacial recombination
losses of the functional layer, causing remarkable loss of power conversion
efficiency (PCE) in industrial production. Here, a fullerene-substituted
alkylphosphonic acid dipole layer is introduced between the R2R-printed tin
oxide electron transport layer and the perovskite active layer to reduce the
energetic barrier and to suppress surface recombination at the buried
interface. The resulting f-PSCs exhibit a PCE of 17.0% with negligible
hysteresis, retain 95% of their initial PCE over 3000 bending cycles and
achieve a T95 lifetime of 1200 h under 1 sun and 65 degreeC in nitrogen
atmosphere. Moreover, the fully printed flexible perovskite solar mini-modules
(f-PSMs) with a 20.25 cm2 aperture area achieve a PCE of 11.6%. The
encapsulated f-PSMs retain 90% of their initial PCE after 500 h damp-heat
testing at 65 degreeC and 85% relative humidity (ISOS-D3). This work marks an
important progress toward the realization of efficient and stable flexible
perovskite photovoltaics for commercialization.
