Li-TFSI endohedral Metal-Organic frameworks in stable perovskite solar cells for Anti-Deliquescent and restricting ion migration

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 429; p. 132481
• Main Authors: Wang, Jiaqi, Zhang, Jian, Yang, Yulin, Dong, Yayu, Wang, Wei, Hu, Boyuan, Li, Jiao, Cao, Wei, Lin, Kaifeng, Xia, Debin, Fan, Ruiqing
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2022
• Subjects: Encapsulation; Ion migration; Long-term stability; Metal–organic frameworks; Perovskite solar cell; Encapsulation; Perovskite solar cell; Ion migration; Metal–organic frameworks; Long-term stability
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2021.132481

[Display omitted] •The Li-TFSI was encapsulated in the NH2-MIL-101, preventing from attack of water.•The regular oxidation process of doped devices can be performed in an ambient condition.•Amino functionalized Li-TFSI@NH2-MIL-101 could inhibit the ion migration of Pb2+.•This approach realizes an enhanced stability for 10-fold that of conventional devices. Lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) is generally regarded as a conventional p-dopant for classical hole transport material Spiro-OMeTAD, which improves the hole mobility and conductivity of hole-transporting layer (HTL). However, the hygroscopic Li-TFSI would absorb moisture and accelerate the degradation of perovskite film, causing a decline in the long-term stability of perovskite solar cells (PSCs). Herein, a novel dopant Li-TFSI endohedral metal–organic frameworks (namely Li-TFSI@NH2-MIL-101) is constructed for reducing the amount of Li salt and resisting the attack from water molecules. With a significantly decreased Li salt loading mass, the optimal power conversion efficiency (PCE) of 19.01% is achieved for Li-TFSI@ NH2-MIL-101 doped PSCs, which is comparable to that of conventional devices (19.23%). Furthermore, the strong interaction between ammonium groups (–NH2) and uncoordinated Pb2+ ions would passivate the trap states and inhibit ion migration at perovskite/hole transport layer interface, which further improve the device stability. Importantly, this approach realizes an enhanced stability for approximately 10-fold that of conventional devices at the preliminary stage (time to reduce to 90% of initial PCE). The Li-TFSI@NH2-MIL-101 doped PSCs display impressive property stability retaining over 85% of the optimal PCE after 3600 h storage in ambient environment (room temperature and RH ≈ 40%).