Photoactive/Passive Molecular Glass Blends: An Efficient Strategy to Optimize Azomaterials for Surface Relief Grating Inscription

Audrey Laventure, Jeremie Bourotte, Jaana Vapaavuori, Lucas Karperien, Ribal Georges Sabat, Olivier Lebel, Christian Pellerin*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review


Irradiation of azomaterials causes various photophysical and photomechanical effects that can be exploited for the preparation of functional materials such as surface relief gratings (SRGs). Herein, we develop and apply an efficient strategy to optimize the SRG inscription process by decoupling, for the first time, the important effects of the azo content and glass transition temperature (T-g). We prepare blends of a photoactive molecular glass functionalized with the azo Disperse Red 1 (gDR1) with a series of analogous photopassive molecular glasses. Blends with 10 and 40 mol % of gDR1 are completely miscible, present very similar optical properties, and cover a wide range of Tg from below to well above ambient temperature. SRG inscription experiments show that the diffraction efficiency (DE), residual DE, and initial inscription rate reach a maximum when Tg is 25-40 degrees C above ambient temperature for low to high azo content, respectively. Indeed, for a fixed 40 mol % azo content, choosing the optimal T-g enables doubling the SRG inscription rate and increasing DE 6-fold. Moreover, a higher azo content enables higher DE for a similar T-g. Spectroscopy measurements indicate that the photo orientation of DR1 and its thermal stability are maximal with Tg around 70 degrees C, independent of the azo content. We conclude that the SRG potential of azomaterials depends on their capability to photo-orient but that the matrix rigidity eventually limits the inscription kinetics, leading to an optimal T-g that depends on the azo content. This study exposes clear material design guidelines to optimize the SRG inscription process and the photoactivity of azomaterials.

Original languageEnglish
Pages (from-to)798-808
Number of pages11
JournalACS Applied Materials and Interfaces
Issue number1
Publication statusPublished - 11 Jan 2017
MoE publication typeA1 Journal article-refereed


  • surface relief grating
  • photoactive materials
  • azobenzene
  • molecular glasses
  • glass transition temperature
  • photoinduced orientation
  • SIDE

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