Operation Mechanism of Perovskite Quantum Dot Solar Cells Probed by Impedance Spectroscopy

Joseph Luther, Jao Van De Lagemaat, Zahra Zolfaghari, Ehsan Hassanabadi, Didac Pitarch-Tena, Seog Yoon, Zahra Shariatinia, Ivan Mora-Sero

Research output: Contribution to journalArticlepeer-review

75 Scopus Citations

Abstract

We fabricated perovskite quantum dot solar cells (PQDSCs) and varied the thickness of the QD layer by controlling the number of deposition cycles; the cells were systematically investigated with impedance spectroscopy. Despite the evident structural differences with respect to standard perovskite solar cells (PSCs), similar impedance spectra were obtained for PQDSCs, pointing to similar working principles in terms of the active layer. We distinguish two different regimes: At low illumination, recombination is ruled by multiple trapping with trap distributions and/or shunting. However, at higher light intensities, Shockley-Read-Hall recombination is observed. In addition, the low-frequency capacitance, C LF , of PQDSCs increases several orders of magnitude when the illumination is varied from dark to 1-sun conditions. This feature has not been observed in other kinds of photovoltaic devices and is characteristic of PSCs. Although there is no consensus about the exact mechanism responsible for C LF , the suggested models point to an ion migration origin. Its observation in thin-film and PQDSCs devices implies a similar effect in both.

Original languageAmerican English
Pages (from-to)251-258
Number of pages8
JournalACS Energy Letters
Volume4
Issue number1
DOIs
StatePublished - 11 Jan 2019

Bibliographical note

Publisher Copyright:
© 2018 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-72790

Keywords

  • impedance spectroscopy
  • perovskite quantum dot solar cells
  • quantum dots

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