Abstract:
n this paper, we use Polyethylene Oxide (PEO) particles to control the morphology of Formamidinium
(FA)-rich perovskite flms and achieve large grains with improved optoelectronic properties.
Consequently, a planar perovskite solar cell (PSC) is fabricated with additions of 5 wt% of PEO, and the
highest PCE of 18.03% was obtained. This solar cell is also shown to retain up to 80% of its initial PCE
after about 140 h of storage under the ambient conditions (average relative humidity of 62.5± 3.25%)
in an unencapsulated state. Furthermore, the steady-state PCE of the PEO-modifed PSC device
remained stable for long (over 2500 s) under continuous illumination. This addition of PEO particles is
shown to enable the tuning of the optoelectronic properties of perovskite flms, improvements in the
overall photophysical properties of PSCs, and an increase in resistance to the degradation of PSCs.
