Tin (Sn)-based perovskite solar cells (PSCs) have attracted
extensive
attention due to the irlow toxicity and excellent optoelectric properties.
Nonetheless, the development of Sn-based PSCs is still hampered by
poor film quality due to the fast crystallization and the oxidation
from Sn2+ to Sn4+. In this work, we compare
and employ three ethylammonium halides, EAX (X = Cl, Br, I) to explore
their roles in Sn-based perovskites and solar cells. We find that
crystallinity and crystallization orientation of perovskites are optimized
with the regulation of EAI. EABr leads to reduced defect density and
enhanced crystallinity but also the lowest absorption and the widest
band gap owing to the substitution of Br–. Notably,
perovskites with EACl exhibit the best crystallinity, lowest defect
density, and excellent antioxidant capacity benefiting from the partial
substitution of Cl–. Consequently, the EACl-modified
device achieves a champion PCE of 12.50% with an improved V
oc of 0.79 V. Meanwhile, an unencapsulated EACl
device shows excellent shelf stability with negligible efficiency
degradation after 5400 h of storage in a N2-filled glovebox,
and the encapsulated device retains its initial efficiency after continuous
light illumination at the maximum power point for 100 h in air.