**New Insight on Photoisomerization Kinetics of Photo-Switchable Thin Films Based on Azobenzene**/**Graphene Hybrid Additives in Polyethylene Oxide**

#### **Qais M. Al-Bataineh <sup>1</sup> , Ahmad A. Ahmad 1,\*, Ahmad M. Alsaad <sup>1</sup> and Ahmad Telfah 2,3**


Received: 14 November 2020; Accepted: 7 December 2020; Published: 10 December 2020

**Abstract:** In this work, we reported a new insight on the kinetics of photoisomerization and time evolution of hybrid thin films considering the azo-dye methyl red (MR) incorporated with graphene accommodated in polyethylene oxide (PEO). The kinetics of photoisomerization and time-evolution of hybrid thin films were investigated using UV-Vis s and FTIR spectroscopies, as well as appropriate models developed with new analytical methods. The existence of azo-dye MR in the complex is crucial for the resource action of the *trans* ↔ *cis* cycles through UV-illumination ↔ Visible-illumination relaxations. The results of the UV–Vis and the FTIR investigations prove the cyclical *trans* ↔ *cis-*states. Consequently, PEO-(MR-Graphene) hybrid composite thin films can be introduced as possible applicants for photochromic molecular switches, light-gated transistors, and molecular solar thermal energy storage media.

**Keywords:** polymerized nanocomposite thin films; photoisomerization processes; trans-cis-isomers; molecular solar thermal energy storage media; photo-switchable thin films
