Optical and Electrical Characterization of Visible Parylene Films

Abstract

Poly-dichloro-para-xylylene (parylene-C) film is formed through a chemical vapor deposition process, where monomeric gases are polymerized on the target surface at room temperature and are used as transparent insulating coating films. The thin parylene-C films exhibit uniform conformal layers even when deposited on substrates or surfaces with fine cracks, structures, and bumps. However, the film is highly transparent in the visible range (transmittance > 90%); thus, it is difficult to visually identify, inspect the coating process and check for any defects when used as an insulation film. Some reports have demonstrated the deposition of visible (hazy) parylene films through the control of the vaporization or pyrolysis of the parylene-C powder and sublimed dimers, respectively. Even though these films have been applied as device substrates and light extraction layers in organic light-emitting diodes (OLEDs), their optical and electrical characteristics have not been extensively explored, especially for their applications as insulation coatings. In this study, the characteristics of visible parylene films produced by tuning the ratio of dimer to monomer gases via the adjustments of the pyrolysis temperature are analyzed with electrical and optical methods. Parylene-C films deposited within the pyrolysis temperature of 400–700 °C exhibited a haze range of 10–90%. A relative reflectance of 18.8% at 550 nm of the visible light region was achieved in the visible parylene film deposited with a pyrolysis temperature of 400 °C. Resistivity in the order of 1010 Ω cm was achieved for the visible parylene films measured with the transmission line measurement (TLM) method. The films can be applied in advanced insulation coatings for various optical systems and electronic devices.

Introducing a Robust Flexible Conductive Hybrid: Indium Oxide-ParyleneC Obtained by Vapor Phase Infiltration

“…Importantly, the R s values for TMIn/H 2 O 2 increased only by a factor of about 10 from 3 to 33 kΩ/□ after lowering the VPI processing temperature from 210 to 135 °C, respectively, which is 2 orders of magnitude higher than those of the conventionally deposited In 2 O 3 films ( R s = 390 Ω/□) upon annealing at 500 °C . At the same time, the sheet resistance of the hybrid is significantly lower than that of pristine ParyleneC, which showed to be an exceptional electronic insulator with R s values of ∼10 13 –10 14 Ω/□ . The ParyleneC/In x O y hybrid is a blend of two materials of different natures, and consequently, its properties reflect those of both constituents.…”

“…56 At the same time, the sheet resistance of the hybrid is significantly lower than that of pristine ParyleneC, which showed to be an exceptional electronic insulator with R s values of ∼10 13 −10 14 Ω/□. 57 The ParyleneC/In x O y hybrid is a blend of two materials of different natures, and consequently, its properties reflect those of both constituents.…”

A high-performance organic thin-film transistor with Parylene/PMMA bilayer insulation based on P3HT

“…This impedes the crystalline growth of semiconductor molecules and raises the interface trap density. 38 , 39 , 40 , 41 , 42 , 43 , 44 Consequently, the diffusion of organic semiconductor molecules is hindered, leading to a decrease in grain boundaries and crystallinity within the organic semiconductor film. 45 , 46 , 47 Additionally, this situation may result in polarization effects and interface charge capture, adversely affecting device performance.…”

Application of Nanostructured Parylene‐C Films for Improved Optical Characteristics of Organic Light‐Emitting Diodes

“…[3][4][5][6] One of these technologies involves the use of a poly-monochloro-p-xylylene (parylene-C) coating, which is widely used as a conformal coating layer owing to its exceptional chemical resistance and gas barrier properties. [7][8][9][10] DOI: 10.1002/admi. 202400089 The performance of optoelectronic devices, such as organic light-emitting diodes (OLEDs) and organic solar cells (OSCs), is significantly influenced by the refractive index of the thin film.…”

“…[ 3–6 ] One of these technologies involves the use of a poly‐monochloro‐p‐xylylene (parylene‐C) coating, which is widely used as a conformal coating layer owing to its exceptional chemical resistance and gas barrier properties. [ 7–10 ]…”