Strain-induced band gap tuning in flexible ferroelectric/mica thin films

Yu Sun, Ki Hei Wong, Kin Wing Kwok

Research output: Journal article publicationJournal articleAcademic researchpeer-review

1 Citation (Scopus)


Precise control of the band gap is crucial for lead-free ferroelectrics in the application of high-performance optical devices. In this work, we demonstrate that continuous and reversible tuning of optical band gap can be realized through mechanical strain in flexible Ba0.9Ca0.1Ti0.975Fe0.025O3 (BCTF)/mica films. Through bending the flexible films, a large mechanical strain of 0.85% could be introduced into the ferroelectric active layer, leading to a reduction in the band gap of 0.38 eV. The strong dependence of the optical band gap on mechanical bending mainly arisen from the strain-induced modification of Fe-O bond. Because of the superior mechanical property of mica, the flexible BCTF/mica film also exhibits excellent anti-fatigue characteristics over 103 bending cycles. Thus, this work provides an alternate perspective for the design and fabrication of ferroelectric optical devices that cover the entire visible light region.

Original languageEnglish
Article number138741
JournalThin Solid Films
Publication statusPublished - 1 Aug 2021


  • Band gap
  • Ferroelectric
  • Strain
  • Thin film

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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