Investigation of the optical properties of organic‐inorganic hybrid polymers by IR to Vis‐fUV spectroscopic ellipsometry

Abstract

Inorganic-organic hybrid polymers are used as barrier coatings in order to protect flexible electronic devices from the permeation of atmospheric oxygen and water vapour that induce oxidation to the Flexible Electronic Device (FED) organic layers, reducing their operation, efficiency and stability. In this work, Spectroscopic Ellipsometry (SE) in a wide spectral region, from the infrared (IR) (900-4000 cm-1) to the Vis-far UV (1.5-6.5 eV) has been implemented in order to investigate the optical properties of different types of hybrid polymers, which are synthesized via the sol-gel technique onto Polyethylene Terephthalate (PET), SiOx/PET and AlOx/PET substrates. The analysis of the measured SE spectra revealed valuable information about the electronic and vibrational response as well as the cross-linking mechanisms that control the interface and barrier properties of these materials. Finally, the correlation of the optical properties with the synthesis parameters and th e barrier response of these materials will significantly contribute towards their optimization in order to be used as high barrier coatings

Optical properties of hybrid polymers as barrier materials

“…Also, the stretching mode of the carbonyl C O group of PET is shown at 1720 cm À1 . The contribution of the Si-O bonding vibration is dominant in the wavenumber region of 1050-1100 cm À1 [27]. The differences in the vibration band shapes for the various hybrid layers of different thickness values that are observed in he 2 (v)i in Fig.…”

“…The main absorption bands of the hybrid polymers are found in the wavenumber range from 900 to 1800 cm À1 . Among the more intense vibration bands, we can distinguish the glycol CH 2 wagging peak at 1340 cm À1 and the intense complex bands around 1240-1330 cm À1 that arise mainly from ester group vibrations [27]. Also, the stretching mode of the carbonyl C O group of PET is shown at 1720 cm À1 .…”

Real-time optical modelling and investigation of inorganic nano-layer growth onto flexible polymeric substrates

“…In the case of the SiO x film a higher film thickness should be achieved and also it was necessary to investigate how a film with different stoichiometry values is formed (from x = 1 to x = 2), as it will be shown later. The latter is justified by the reports that correlate the SiO x film stoichiometry with other functional properties of the SiO x films grown onto PET, such as barrier properties [2,6].…”

“…and electrodes in order to protect them from the penetration of atmospheric oxygen (O 2 ) and water vapour (H 2 O) molecules into the device that induces degradation and corrosion. Inorganic films such as silicon oxide (SiO x ) and aluminium oxide (AlO x ) which are optically transparent are used as barrier materials [2,6,[10][11][12][13]. The barrier properties, and the quality of these inorganic films depend on many factors, such as the process parameters, the deposition rate and the initial stages of the deposition and the stiffness and smoothness of the substrate [4,5,14].…”

“…Especially in the latter case, the deposition of inorganic functional thin films onto flexible polymeric substrates with nanometer precision is of major importance, since the future flexible organic electronic devices (as flexible organic light emitting diodes, flexible organic solar cells and organic circuits) are consisted of a multilayer structure of inorganic, organic and hybrid nano-layers [1][2][3][4][5]. Therefore, the complex interface effects that occur due to the different chemical structures of the subsequent nano-layers have to be understood and controlled in order to functionalize the individual layers with the ultimate aim to optimize the device performance and stability [2,[6][7][8][9].…”