Surface properties are often assessed with measurements of the contact angle of a water drop. The process is however flawed for the very important class of hybrid perovskite materials, extensively employed in solar cells and optoelectronics research, because they are water soluble and their surface degrades during contact angle measurements. While hybrid perovskites are considered to be highly hydrophilic, a contact angle with water of 83° can be measured, as if they were almost hydrophobic. By combining experiments and simulations, the actual value is explained as the result of the interaction of water with degraded superficial layers that form over sub-millisecond time scale at the water/perovskite interface. The models are validated against contact angle measurements for water on a variety of substrates, and are referenced to with the Young–Dupré relation between liquid–solid adhesion and contact angle. Present work reconciles the hydrophilic nature of methylammonium lead iodide with the apparent hydrophobic behavior in contact angle measurements, proposing a methodology for the study of contact angle on evolving substrates.

Hydrophilicity and Water Contact Angle on Methylammonium Lead Iodide

Meloni S.;
2019

Abstract

Surface properties are often assessed with measurements of the contact angle of a water drop. The process is however flawed for the very important class of hybrid perovskite materials, extensively employed in solar cells and optoelectronics research, because they are water soluble and their surface degrades during contact angle measurements. While hybrid perovskites are considered to be highly hydrophilic, a contact angle with water of 83° can be measured, as if they were almost hydrophobic. By combining experiments and simulations, the actual value is explained as the result of the interaction of water with degraded superficial layers that form over sub-millisecond time scale at the water/perovskite interface. The models are validated against contact angle measurements for water on a variety of substrates, and are referenced to with the Young–Dupré relation between liquid–solid adhesion and contact angle. Present work reconciles the hydrophilic nature of methylammonium lead iodide with the apparent hydrophobic behavior in contact angle measurements, proposing a methodology for the study of contact angle on evolving substrates.
2019
Caddeo, C.; Marongiu, D.; Meloni, S.; Filippetti, A.; Quochi, F.; Saba, M.; Mattoni, A.
File in questo prodotto:
File Dimensione Formato  
Caddeo_et_al-2019-Advanced_Materials_Interfaces.pdf

solo gestori archivio

Descrizione: Full text editoriale
Tipologia: Full text (versione editoriale)
Licenza: NON PUBBLICO - Accesso privato/ristretto
Dimensione 1.82 MB
Formato Adobe PDF
1.82 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2406432
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 40
  • ???jsp.display-item.citation.isi??? 39
social impact