Reconsidering figures of merit for performance and stability of perovskite photovoltaics

Mark V. Khenkin, K. M. Anoop, Iris Visoly-Fisher, Yulia Galagan, Francesco Di Giacomo, Bhushan Ramesh Patil, Golnaz Sherafatipour, Vida Turkovic, Horst Günter Rubahn, Morten Madsen, Tamara Merckx, Griet Uytterhoeven, João P.A. Bastos, Tom Aernouts, Francesca Brunetti, Monica Lira-Cantu, Eugene A. Katz

Research output: Contribution to journalArticlepeer-review


The development of hybrid organic-inorganic halide perovskite solar cells (PSCs) that combine high performance and operational stability is vital for implementing this technology. Recently, reversible improvement and degradation of PSC efficiency have been reported under illumination-darkness cycling. Quantifying the performance and stability of cells exhibiting significant diurnal performance variations is challenging. We report the outdoor stability measurements of two types of devices showing either reversible photo-degradation or reversible efficiency improvement under sunlight. Instead of the initial (or stabilized) efficiency and T80 as the figures of merit for the performance and stability of such devices, we propose using the value of the energy output generated during the first day of exposure and the time needed to reach its 20% drop, respectively. The latter accounts for both the long-term irreversible degradation and the reversible diurnal efficiency variation and does not depend on the type of process prevailing in a given perovskite cell.

Original languageAmerican English
Pages (from-to)739-743
Number of pages5
JournalEnergy and Environmental Science
Issue number4
StatePublished - 1 Apr 2018

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Pollution


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