Revealing the Degradation and Self-Healing Mechanisms in Perovskite Solar Cells by Sub-Bandgap External Quantum Efficiency Spectroscopy

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

17 Scopus Citations
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Author(s)

  • Xixia Liu
  • Zhiqiang Guan
  • Armin Gerhard Aberle
  • Fen Lin

Detail(s)

Original languageEnglish
Pages (from-to)2006170
Journal / PublicationAdvanced Materials
Volume33
Issue number3
Online published9 Dec 2020
Publication statusPublished - 21 Jan 2021

Abstract

Ion dissociation has been identified to determine the intrinsic stability of perovskite solar cells (PVSCs), but the underlying degradation mechanism is still elusive. Herein, by combining highly sensitive sub-bandgap external quantum efficiency (s-EQE) spectroscopy, impedance analysis, and theoretical calculations, the evolution of defect states in PVSCs during the degradation can be monitored. It is found that the degradation of PVSCs can be divided into three steps: 1) dissociation of ions from perovskite lattices, 2) migration of dissociated ions, and 3) consumption of I by reacting with metal electrode. Importantly, step (3) is found to be crucial as it will accelerate the first two steps and lead to continuous degradation. By replacing the metal with more chemically robust indium tin oxide (ITO), it is found that the dissociated ions under light soaking will only saturate at the perovskite/ITO interface. Importantly, the dissociated ions will subsequently restore to the corresponding vacancies under dark condition to heal the perovskite and photovoltaic performance. Such shuttling of mobile ions without consumption in the ITO-contact PVSCs results in harvesting–rest–recovery cycles in natural day/night operation. It is envisioned that the mechanism of the intrinsic perovskite material degradation reported here will lead to clearer research directions toward highly stable PVSCs.

Research Area(s)

  • degradation, indium tin oxide contact, ion consumption, ion dissociation, perovskite solar cells, self-healing, sub-bandgap external quantum efficiency

Citation Format(s)

Revealing the Degradation and Self-Healing Mechanisms in Perovskite Solar Cells by Sub-Bandgap External Quantum Efficiency Spectroscopy. / Cheng, Yuanhang; Liu, Xixia; Guan, Zhiqiang; Li, Menglin; Zeng, Zixin; Li, Ho-Wa; Tsang, Sai-Wing; Aberle, Armin Gerhard; Lin, Fen.

In: Advanced Materials, Vol. 33, No. 3, 21.01.2021, p. 2006170.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review