Interfacial Engineering with Cross-Linkable Fullerene Derivatives for High-Performance Perovskite Solar Cells

Tin Kang, Cheng Min Tsai, Yu He Jiang, Ganesh Gollavelli, Nayantara Mohanta, Wei-Guang Diau*, Chain-Shu Hsu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Two fullerene derivatives with styryl and oxetane cross-linking groups served as interfacial materials to modify an electron-transporting layer (ETL) of TiO2, doped with Au nanoparticles, processed under low-temperature conditions to improve the performance of perovskite solar cells (PSC). The cross-linkable [6,6]-phenyl-C61-butyric styryl dendron ester was produced via thermal treatment at 160 °C for 20 min, whereas the cross-linkable [6,6]-phenyl-C61-butyric oxetane dendron ester (C-PCBOD) was obtained via UV-curing treatment for 45 s. Both cross-linked fullerenes can passivate surface-trap states of TiO2 and have also excellent surface coverage on the TiO2 layer shown in the corresponding atomic force microscopy images. To improve the crystallinity of perovskite, we propose a simple co-solvent method involving mixing dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a specific ratio (DMF/DMSO = 90/10). The fullerene derivative layer between the ETL and perovskite layers significantly improved electron extraction and suppressed charge recombination by decreasing the density of traps at the ETL surface. A planar PSC device was fabricated with the configuration indium tin oxide/TiO2 (Au)/C-PCBOD/perovskite/spiro-OMeTAD/Au to attain a power conversion efficiency (PCE) of 15.9%. The device performance was optimized with C-PCBOD as an interfacial mediate to modify the surface of the mesoporous TiO2 ETL; the C-PCBOD-treated device attained a significantly enhanced performance, PCE 18.3%. Electrochemical impedance spectral and photoluminescence decay measurements were carried out to understand the characteristics of electron transfer and charge recombination of the perovskite/TiO2 samples with and without a fullerene interfacial layer.

Original languageEnglish
Pages (from-to)38530-38536
Number of pages7
JournalACS Applied Materials and Interfaces
Volume9
Issue number44
DOIs
StatePublished - 8 Nov 2017

Keywords

  • cross-linkable fullerene
  • electrochemical impedance spectroscopy
  • ETL
  • interfacial layer
  • photoluminescence decay
  • PSC
  • titanium oxide

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