Spontaneous Interface Healing by a Dynamic Liquid‐Crystal Transition for High‐Performance Perovskite Solar Cells. Issue 49 (1st November 2022)

• Record Type: Journal Article
• Authors: Du, Xinyi; Zhang, Lu; Chen, Ran; You, Jiaxue; Ma, Yabin; Wang, Jungang; Wu, Yin; Liu, Baibai; Zhao, Kui; Chen, Jiangzhao; Chen, Xinbing; An, Zhongwei; Liu, Shengzhong (Frank)
• Is Part Of: Advanced materials. Volume 34:Issue 49(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-01
• Subjects: crystallization retardation -- dynamic liquid‐crystal transitions -- high efficiency and stability -- interfacial healing -- perovskite solar cells; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202207362
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Low‐temperature solution processing of thin‐film semiconductors is more cost‐effective than traditional vacuum processing; however, it leads to more defects during fast bulk crystallization and residual tensile stress. Herein, a new strategy of dynamic liquid‐crystal transition (DLCT) is developed to solve these problems in one step. The design principle is used to suggest that the DLCT molecule should firstly interact with the perovskite grains in the bulk and meanwhile go through a dynamic transition to spontaneously heal the interface. A thermotropic LC molecule (CBO6SS6OCB) is then designed to demonstrate the strategy. The LC interacting with perovskite colloid forms an intermediate adduct to retard the crystallization. The annealing processes stimulate the concentrated LC solid, causing it to flow to the electron transport layer to release the residual stress to attain improved electron extraction. Consequently, the device efficiency is increased to 24.38%, where its V OC of 1.184 V is among the best for the formamidine‐based perovskite solar cells. Furthermore, the ambient stability (93.0% of initial efficiency after 2000 h of aging) and light stability (96.3% of initial efficiency after 500 h of aging) are much improved. This work conceives a new engineering of additive phase transition for high‐performance perovskite solar cells. Abstract : Liquid‐crystal (LC) molecules interacting with PbI2 retard the crystallization of the perovskite film, and finally increase the grain size. During annealing, the LC molecules undergo a phase transition, and then the flowable LC is extracted by the lower interface to release the residual stress, and accelerate electron extraction. A new engineering of additive phase transition is thus conceived.