Copper(I) Iodide as Hole‐Conductor in Planar Perovskite Solar Cells: Probing the Origin of J–V Hysteresis |
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Authors: | Gaveshana A Sepalage Steffen Meyer Alexander Pascoe Andrew D Scully Fuzhi Huang Udo Bach Yi‐Bing Cheng Leone Spiccia |
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Affiliation: | 1. School of Chemistry, Monash University, Victoria, Australia;2. Department of Materials Science and Engineering, Monash University, Victoria, Australia;3. CSIRO Manufacturing Flagship, Clayton, Victoria, Australia;4. Tech Fellow, The Melbourne Centre for Nanofabrication, Clayton, Victoria, Australia |
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Abstract: | Organic–inorganic lead halide perovskite solar cells are promising alternatives to silicon‐based cells due to their low material costs and high photovoltaic performance. In this work, thin continuous perovskite films are combined with copper(I) iodide (CuI) as inorganic hole‐conducting material to form a planar device architecture. A maximum conversion efficiency of 7.5% with an average efficiency of 5.8 ± 0.8% is achieved which, to our knowledge, is the highest reported efficiency for CuI‐based devices with a planar structure. In contrast to related planar 2,2′,7,7′‐tetrakis‐(N,N ‐di‐4‐methoxyphenylamino)‐9,9′‐spirobifluorene (spiro‐OMeTAD)‐based devices, the CuI‐based devices do not show a pronounced hysteresis when tested by scanning the potential in a forward and backward direction. The strong quenching of photoluminescence (PL) signal and comparatively fast decay of open‐circuit voltage demonstrates a more rapid removal of positive charge carriers from the perovskite layer when in contact with CuI compared to spiro‐OMeTAD. A slow response on a timescale of 10–100 s is observed for the spiro‐OMeTAD‐based devices. In comparison, the CuI‐based device displays a significantly faster response as determined through electrochemical impedance spectroscopy (EIS) and open‐circuit voltage decays (OCVDs). The characteristically slow kinetics measured through EIS and OCVD are linked directly to the current–voltage hysteresis. |
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Keywords: | copper(I) iodide inorganic hole‐conductors J– V hysteresis methylammonium lead iodide perovskite solar cells |
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