Femtosecond Charge-Injection Dynamics at Hybrid Perovskite Interfaces

Giulia Grancini, Daniele Viola, Yonghui Lee, Michael Saliba, Sanghyun Paek, Kyung Taek Cho, Simonetta Orlandi, Marco Cavazzini, Fernando Fungo, Mohammad Hossain, Abdelhak Belaidi, Nouar Tabet, Gianluca Pozzi, Giulio Cerullo, Mohammad Khaja Nazeeruddin

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19 Citations (Scopus)

Abstract

With a power conversion efficiency (PCE) exceeding 22 %, perovskite solar cells (PSCs) have thrilled photovoltaic research. However, the interface behavior is still not understood and is a hot topic of research: different processes occur over a hierarchy of timescales, from femtoseconds to seconds, which makes perovskite interface physics intriguing. Herein, through femtosecond transient absorption spectroscopy with spectral coverage extending into the crucial IR region, the ultrafast interface-specific processes at standard and newly molecularly engineered perovskite interfaces in state-of-the-art PSCs are interrogated. Ultrafast interfacial charge injection occurs with a time constant of 100 fs, resulting in hot transfer from energetic charges and setting the timescale for the first step involved in the complex charge-transfer process. This is also true for 20 % efficient devices measured under real operation, for which the femtosecond injection is followed by a slower picosecond component. These findings provide compelling evidence for the femtosecond interfacial charge-injection step and demonstrate a robust method for the straightforward identification of interfacial non-equilibrium processes on the ultrafast timescale.

Original languageEnglish
Pages (from-to)2381-2389
Number of pages9
JournalChemPhysChem
Volume18
Issue number17
DOIs
Publication statusPublished - 6 Sep 2017

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Keywords

  • interface physics
  • IR spectroscopy
  • perovskite solar cells
  • photophysics
  • ultrafast spectroscopy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

Cite this

Grancini, G., Viola, D., Lee, Y., Saliba, M., Paek, S., Cho, K. T., Orlandi, S., Cavazzini, M., Fungo, F., Hossain, M., Belaidi, A., Tabet, N., Pozzi, G., Cerullo, G., & Nazeeruddin, M. K. (2017). Femtosecond Charge-Injection Dynamics at Hybrid Perovskite Interfaces. ChemPhysChem, 18(17), 2381-2389. https://doi.org/10.1002/cphc.201700492