Crystalline Molybdenum Oxide Thin-Films for Application as Interfacial Layers in Optoelectronic Devices

André L.F. Cauduro*, Roberto Dos Reis, Gong Chen, Andreas K. Schmid, Christophe Méthivier, Horst Günter Rubahn, Léo Bossard-Giannesini, Hervé Cruguel, Nadine Witkowski, Morten Madsen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

The ability to control the interfacial properties in metal-oxide thin films through surface defect engineering is vital to fine-tune their optoelectronic properties and thus their integration in novel optoelectronic devices. This is exemplified in photovoltaic devices based on organic, inorganic or hybrid technologies, where precise control of the charge transport properties through the interfacial layer is highly important for improving device performance. In this work, we study the effects of in situ annealing in nearly stoichiometric MoOx (x ∼ 3.0) thin-films deposited by reactive sputtering. We report on a work function increase of almost 2 eV after inducing in situ crystallization of the films at 500 °C, resulting in the formation of a single crystalline α-MoO3 overlaid by substoichiometric and highly disordered nanoaggregates. The surface nanoaggregates possess various electronic properties, such as a work function ranging from 5.5 eV up to 6.2 eV, as determined from low-energy electron microscopy studies. The crystalline underlayer possesses a work function greater than 6.3 eV, up to 6.9 eV, characteristic of a very clean and nearly defect-free MoO3. By combining electronic spectroscopies together with structural characterizations, this work addresses a novel method for tuning, and correlating, the optoelectronic properties and microstructure of device-relevant MoOx layers.

Original languageEnglish (US)
Pages (from-to)7717-7724
Number of pages8
JournalACS Applied Materials and Interfaces
Volume9
Issue number8
DOIs
StatePublished - Mar 1 2017
Externally publishedYes

Keywords

  • Reactive sputtering
  • electronic properties of metal-oxide surfaces
  • postannealing
  • single crystalline MoO thin films
  • substoichiometric nanoaggregates

ASJC Scopus subject areas

  • Materials Science(all)

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