posted on 2021-07-09, 05:34authored byYuanyuan Zhang, Qiao Chen, Hyun-Seock Yang, Danbi Kim, Insoo Shin, Bo Ram Lee, Joo Hyun Kim, Doo Kyung Moon, Kwang Ho Kim, Sung Heum Park
Despite
tremendous progress in the power conversion efficiency
(PCE) of perovskite solar cells (PeSCs), the long-term stability issue
remains a significant challenge for commercialization. In this study,
by blending organic halide salts, phenylethylammonium halide (PEAX,
X = I, Br), with CH3NH3PbI3 (MAPbI3), we achieved remarkable enhancements in the water-repellency
of perovskite films and long-term stability of PeSCs, together with
enhanced PCE. The hydrophobic aromatic PEA+ group in PEAX
protects the perovskite film from destruction by water. In addition,
the smaller halide Br– in PEABr restructures MAPbI3 to form MAPbI3–xBrx during post-annealing, leading to lattice
contraction with beneficial crystallization quality. The perovskite
films modified by PEAX exhibited excellent water resistance. When
the perovskite films were directly immersed in water, no obvious decompositions
were observed, even after 60 s. The PEAX-decorated PeSCs exhibited
considerable long-term stability. Under high-humidity conditions (60
± 5%), the PEAX-decorated PeSCs held 80.5% for PEAI and 85.2%
for PEABr of their original PCE after exposure for 100 h, whereas
the pristine PeSC device lost more than 99% of its initial PCE after
exposure for 60 h under the same conditions. Moreover, compared to
the pristine device with a PCE of 13.28%, the PEAX-decorated PeSCs
exhibited enhanced PCEs of 17.33% for the PEAI device and 17.18% for
the PEABr device.