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Hydrogen bonding drives the self-assembling of carbazole-based hole-transport material for enhanced efficiency and stability of perovskite solar cells

Year: 2022

Journal: Nano Energy, Volume 101, OCT

Authors: Wang, Cheng; Liu, Maning; Rahman, Sunardi; Pasanen, Hannu Pekka; Tian, Jingshu; Li, Jianhui; Deng, Zhifeng; Zhang, Haichang; Vivo, Paola

Organizations: Jane and Aatos Erkko foundation, Finland (SOL-TECH project); Finnish Cultural Foundation, Finland [00220107]; Young Taishan Scholars, PR China [201909120]; Academy of Finland Flagship Programme, Photonics Research and Innovation (PREIN) [320165]

Keywords: Self-assembly; Hydrogen bonding; Hole-transport materials; Interfaces; Perovskite solar cells; Stability

Designing a hole-transport material (HTM) that guarantees effective hole transport while self-assembling at the perovskite vertical bar HTM interface with the formation of an ordered interlayer, has recently emerged as a promising strategy for high-performance and stable perovskite solar cells (PSCs). Hydrogen bonding (HB) is a versatile multi-functional tool for the design of small molecular HTMs. However, to date, its employment is mostly limited to p-i-n inverted PSCs. This study demonstrates the advantages of a novel HTM design that can self-assemble into a long-range ordered interlayer on the perovskite surface via HB association. A hydro-functional HTM (O1) is compared to a reference HTM (O2) that cannot form HB due to the replacement of the amide group of O1 with a plain butyl alkyl chain in O2. As a result, O1-based n-i-p PSCs display enhanced hole extraction reaction, suppressed interfacial charge recombination, reduced hysteresis effect, and an increase in V-oc (by 60 mV), FF (>11% increase), and overall power conversion efficiency, PCE (32% increase) compared to the case of HB-free O2-based devices. Remarkable stability is observed for unencapsulated O1 cells, with a T-80 lifetime of 35.5 h under continuous maximum power point tracking in air. This work emphasizes the role of HB-directed self-assembling in simultaneously enhancing both the PCE and stability of popular n-i-p PSCs. This study paves the way for the development of new hydro-functional charge-transport material designs for efficient and stable PSCs.