Copper(I) iodide as hole-conductor in planar perovskite solar cells: probing the origin of J-V hysteresis

Gaveshana Anuradha Sepalage, Steffen Meyer, Alexander Robert Pascoe, Andrew D Scully, Fuzhi Huang, Udo Bach, Yibing Cheng, Leone Spiccia

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185 Citations (Scopus)

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. Planar perovskite/copper(I) iodide solar cells with near to no J-V hysteresis, made by employing thin CuI and perovskite layers, result in a record conversion efficiency of 7.5%. The magnitude of dielectric polarization at the perovskite/hole-conductor interface is proposed to influence the degree of J-V hysteresis
Original languageEnglish
Pages (from-to)5650-5661
Number of pages12
JournalAdvanced Functional Materials
Volume25
Issue number35
DOIs
Publication statusPublished - 2015

Keywords

  • copper(I) iodide
  • inorganic hole-conductors
  • J-V hysteresis
  • methylammonium lead iodide
  • perovskite solar cells

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