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Tailored Amphiphilic Molecular Mitigators for Stable Perovskite Solar Cells With 23.5% Efficiency

Hongwei Zhu, Yuhang Liu, Felix T Eickemeyer, Linfeng Pan, Dan Ren, Marco A Ruiz-Preciado, Brian Carlsen, Bowen Yang, Xiaofei Dong, Zaiwei Wang, Hongli Liu, Shirong Wang, Shaik M Zakeeruddin, Anders Hagfeldt, etc.

Adv Mater. 2020 Mar;32(12):e1907757.

PMID: 32068922

Abstract:

Passivation of interfacial defects serves as an effective means to realize highly efficient and stable perovskite solar cells (PSCs). However, most molecular modulators currently used to mitigate such defects form poorly conductive aggregates at the perovskite interface with the charge collection layer, impeding the extraction of photogenerated charge carriers. Here, a judiciously engineered passivator, 4-tert-butyl-benzylammonium iodide (tBBAI), is introduced, whose bulky tert-butyl groups prevent the unwanted aggregation by steric repulsion. It is found that simple surface treatment with tBBAI significantly accelerates the charge extraction from the perovskite into the spiro-OMeTAD hole-transporter, while retarding the nonradiative charge carrier recombination. This boosts the power conversion efficiency (PCE) of the PSC from ≈20% to 23.5% reducing the hysteresis to barely detectable levels. Importantly, the tBBAI treatment raises the fill factor from 0.75 to the very high value of 0.82, which concurs with a decrease in the ideality factor from 1.72 to 1.34, confirming the suppression of radiation-less carrier recombination. The tert-butyl group also provides a hydrophobic umbrella protecting the perovskite film from attack by ambient moisture. As a result, the PSCs show excellent operational stability retaining over 95% of their initial PCE after 500 h full-sun illumination under maximum-power-point tracking under continuous simulated solar irradiation.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
LS72745 Benzylammonium iodide Benzylammonium iodide Price
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