Suppression of Hysteresis Effects in Organohalide Perovskite Solar Cells

Thin‐film solar cell based on hybrid perovskites shows excellent light‐to‐power conversion efficiencies exceeding 22%. However, the mixed ionic‐electronic semiconductor hybrid perovskite exhibits many unusual properties such as slow photocurrent instabilities, hysteresis behavior, and low‐frequency...

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Bibliographic Details
Published in:Advanced materials interfaces 2017-06, Vol.4 (11), p.n/a
Main Authors: Hou, Yi, Scheiner, Simon, Tang, Xiaofeng, Gasparini, Nicola, Richter, Moses, Li, Ning, Schweizer, Peter, Chen, Shi, Chen, Haiwei, Quiroz, Cesar Omar Ramirez, Du, Xiaoyan, Matt, Gebhard J., Osvet, Andres, Spiecker, Erdmann, Fink, Rainer H., Hirsch, Andreas, Halik, Marcus, Brabec, Christoph J.
Format: Article
Language:English
Subjects:
Bonding strength
Buckminsterfullerene
Current carriers
Energy conversion efficiency
Fullerenes
hysteresis behavior
Impedance
Indium tin oxides
interfaces engineering
ion migration
perovskite solar cells
Photoelectric effect
Photovoltaic cells
self‐assembled monolayers
Solar cells
Substrates
Thin films
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Summary:Thin‐film solar cell based on hybrid perovskites shows excellent light‐to‐power conversion efficiencies exceeding 22%. However, the mixed ionic‐electronic semiconductor hybrid perovskite exhibits many unusual properties such as slow photocurrent instabilities, hysteresis behavior, and low‐frequency giant capacitance, which still question us so far. This study presents a direct surface functionalization of transparent conductive oxide electrode with an ultrathin ≈2 nm thick phosphonic acid based mixed C60/organic self‐assembled monolayer (SAM) that significantly reduces hysteresis. Moreover, due to the strong phosphonates bonds with indium tin oxide (ITO) substrates, the SAM/ITO substrates also exhibit an excellent recyclability merit from the perspective of cost effectiveness. Impedance studies find the fingerprint of an ion‐based diffusion process in the millisecond to second regime for TiO2‐based devices, which, however, is not observed for SAM‐based devices at these low frequencies. It is experimentally demonstrated that ion migration can be considerably suppressed by carefully engineering SAM interfaces, which allows effectively suppressing hysteresis and unstable diode behavior in the frequency regime between ≈1 and 100 Hz. It is suggested that a reduced density of ionic defects in combination with the absence of charge carrier accumulation at the interface is the main physical origin for the reduced hysteresis. A high PCE of 17.1% for a planar structured perovskite solar cell is presented by simply depositing a phosphonic acid based mixed self‐assembled monolayer (SAM) layer on top of transparent electrodes. This ultrathin SAM layer improves not only the charge extraction but also the crystalline quality of perovskite films and results in an effectively suppressed hysteresis effect.
ISSN:2196-7350
2196-7350
DOI:10.1002/admi.201700007