Film Flip and Transfer Process to Enhance Light Harvesting in Ultrathin Absorber Films on Specular Back-Reflectors

Asaf Kay, Barbara Scherrer, Yifat Piekner, Kirtiman Deo Malviya, Daniel A. Grave, Hen Dotan, Avner Rothschild

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Optical interference is used to enhance light–matter interaction and harvest broadband light in ultrathin semiconductor absorber films on specular back-reflectors. However, the high-temperature processing in oxygen atmosphere required for oxide absorbers often degrades metallic back-reflectors and their specular reflectance. In order to overcome this problem, a newly developed film flip and transfer process is presented that enables high-temperature processing without degradation of the metallic back-reflector and without the need of passivation interlayers. The film flip and transfer process improves the performance of photoanodes for photoelectrochemical water splitting comprising ultrathin (<20 nm) hematite (α-Fe2O3) films on silver–gold alloy (90 at% Ag–10 at% Au) back-reflectors. Specular back-reflectors are obtained with high reflectance below hematite films, which is necessary for maximizing the productive light absorption in the hematite film and minimizing nonproductive absorption in the back-reflector. Furthermore, the film flip and transfer process opens up a new route to attach thin film stacks onto a wide range of substrates including flexible or temperature sensitive materials.

Original languageEnglish
Article number1802781
JournalAdvanced Materials
Issue number35
StatePublished - 29 Aug 2018
Externally publishedYes


  • hematite
  • light trapping
  • ultrathin films
  • ultrathin optical absorbers
  • water splitting

ASJC Scopus subject areas

  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering


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