Imide-functionalized acceptor-acceptor copolymers as efficient electron transport layers for high-performance perovskite solar cells

Yongqiang Shi, Wei Chen, Ziang Wu, Yang Wang, Weipeng Sun, Kun Yang, Yumin Tang, Han Young Woo, Ming Zhou, Aleksandra B. Djurišić, Zhubing He, Xugang Guo

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Electron transport layers (ETLs) are critical for improving device performance and stability of perovskite solar cells (PVSCs). Herein, a distannylated electron-deficient bithiophene imide (BTI-Tin) is synthesized, which enables us to access structurally novel acceptor-acceptor (A-A) type polymers. Polymerizing BTI-Tin with dibrominated naphthalene diimide (NDI-Br) and perylene diimide (PDI-Br) affords two A-A copolymers P(BTI-NDI) and P(BTI-PDI). The all-acceptor backbone yields both low-lying highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels for the polymers, which combined with their high electron mobility render P(BTI-NDI) and P(BTI-PDI) as promising ETLs for perovskite solar cells (PVSCs). When applied as ETLs to replace the conventional [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) in planar p-i-n PVSCs, the PC61BM-free devices based on P(BTI-NDI) and P(BTI-PDI) achieve remarkable power conversion efficiencies (PCEs) of 19.5% and 20.8%, respectively, with negligible hysteresis. Such performance is attributed to efficient electron extraction and reduced charge recombination. Moreover, the devices based on P(BTI-NDI) and P(BTI-PDI) ETLs show improved stability compared to the PC61BM based ones due to the higher hydrophobicity of the new ETLs. This work provides important guidelines for designing n-type polymers to replace PC61BM as efficient ETLs for high-performance PVSCs with improved stability.

Original languageEnglish
Pages (from-to)13754-13762
Number of pages9
JournalJournal of Materials Chemistry A
Issue number27
Publication statusPublished - 2020 Jul 21

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)


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