Observable Hysteresis at Low Temperature in 鈥淗ysteresis Free鈥?Organic鈥揑norganic Lead Halide Perovskite Solar Cells

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• 作者：Daniel Bryant ; Scot Wheeler ; Brian C. O鈥橰egan ; Trystan Watson ; Piers R. F. Barnes ; Dave Worsley ; James Durrant
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：August 20, 2015
• 年：2015
• 卷：6
• 期：16
• 页码：3190-3194
• 全文大小：322K
• ISSN：1948-7185

文摘

In this paper we address the JV hysteresis behavior of planar organic鈥搃norganic lead halide perovskite solar cells fabricated using PC₆₀BM as the cathode. At room temperature, these devices exhibit apparently hysteresis free JV scans. We observe that cooling the temperature to 175 K results in the appearance of substantial JV hysteresis. Employing chronoamperometric measurements, we demonstrate that the half-time for the relaxation process underlying this hysteresis slows from 0.6 s at 298 K to 15.5 s at 175 K, yielding an activation energy of 0.12 eV. We further demonstrate that by cooling a cell to 77 K while held under positive bias, we are able to 鈥渇reeze鈥?the cell into the most favorable condition for efficient photovoltaic performance. We thus conclude that changes to device architecture that appear to remove room temperature JV hysteresis may not remove the underlying process(es), but rather shift them to time scales not readily observable in typical room temperature JV scans.