Phenylethylammonium iodide induced “in situ healing” behavior for carbon-electrode basing, hole-conductor-free perovskite solar cells

Previous study showed that blending octylammonium iodide (OAI) in a carbon paste induced a kind of in situ healing effect for carbon-electrode basing, hole-conductor-free, planar perovskite solar cells. Here, the strategy is re-examined by considering another kind of ammonium halide molecule or phenethylammonium iodide (PEAI). It is observed that, after moderate PEAI blending, power conversion efficiency of devices rises from 11.56 (±0.82)% to 15.77 (±0.53)% (championed at ∼17.9%), with open-circuit voltage increasing from 969 (±28) to 1033 (±13) mV, and fill factor increasing from 51.17 (±2.68)% to 65.71 (±1.36)%. The improved device efficiency is due to the retarded charge recombination and the improved charge transfer processes. Transient photovoltage/photocurrent decay curve tests show that, after PEAI blending, lifetime of charge carriers in device increases from 3.21 to 5.67 μs, while the charge extraction time decreases from 2.99 to 2.18 μs. Moreover, built-in potential rises according to the Mott–Schottky study. A designated “penetration-reaction” test reveals that PEAI could also induce the in situ healing effect, which accounts for the improved charge transfer/recombination processes. The study could tell the universality of this strategy to certain extent.