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Copper(I) Iodide as Hole‐Conductor in Planar Perovskite Solar Cells: Probing the Origin of J – V Hysteresis
Author(s) -
Sepalage Gaveshana A.,
Meyer Steffen,
Pascoe Alexander,
Scully Andrew D.,
Huang Fuzhi,
Bach Udo,
Cheng YiBing,
Spiccia Leone
Publication year - 2015
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201502541
Subject(s) - materials science , perovskite (structure) , hysteresis , halide , dielectric spectroscopy , optoelectronics , iodide , planar , open circuit voltage , energy conversion efficiency , photoluminescence , photovoltaic system , electrode , chemical engineering , analytical chemistry (journal) , electrochemistry , voltage , inorganic chemistry , condensed matter physics , chemistry , electrical engineering , organic chemistry , physics , computer graphics (images) , computer science , engineering
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.