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Flexible, colorless, versatile

Transparent, Flexible Substrate for Consumer Devices and Aerospace Applications

Kolon Colorless Polyimide Films. Inspiring what's next.

Kolon Industries, Inc., has developed a new colorless polyimide (CPI™) material with the potential to revolutionize flexible electronics, consumer devices, organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), printed circuit boards (PCBs), and myriad aerospace applications. Kolon CPI™ films offer high-temperature stability, superior mechanical properties, and other unique features that provide companies with the opportunity to take advantage of better flexible materials for the next generation of consumer and aerospace technologies.

Based on technology initially developed at NASA, Kolon's patented, radiation-hard material is stable and easy to process in organic solvents, with roll-to-roll processing capabilities. Satisfying stringent criteria for flexible substrates, Kolon CPI films offer optical transparency approaching 90%, a super-smooth surface finish, and tunable dielectric properties. The multipurpose material is available not only in film form (thickness ranging from 10 µm to 100 µm) but also as a varnish for coatable surfaces. More information about the features of this innovative CPI material appears below.

Put this innovative technology to work for your business by purchasing the material from Kolon, manufacturing it as a joint venture with Kolon, or collaborating with Kolon on further R&D.

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Kolon's CPI material offers several features that make it useful for a wide range of applications:

  • High clarity, colorless: Kolon's optically transparent material offers light-transmission properties that are greater than 88% at 550 nm.
  • High-temperature stability: The material’s glass transition temperature is >330 °C, and its coefficient of thermal expansion (CTE) is <15 ppm/°C. The material is thermo-mechanically stable at 20–150 °C for up to 3 hours.
  • Effective moisture barrier: The material absorbs less than 1% of water coming into contact with its surface.
  • Smooth surface: The polyimide's surface roughness is less than 10 nm, making it ideal for use as a film substrate for display backplanes, OLEDs, OPVs, and other applications.
  • Radiation tolerant: Unlike other polyimides, Kolon's CPI material is rad-hard, making it ideal for use in certain applications.
  • Acid/solvent tolerant: Tests have shown that Kolon's CPI material is resistant to acids as well as certain solvents and alkalis, with further research underway.
  • Excellent surface hardness: Pencil hardness testing demonstrated exceeding H at 1-kgf loading.

Detailed specifications appear below.

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flexible transparent newspaper

solar panels

Kolon's CPI material can be incorporated into a variety of products that use flexible and transparent substrates.

Consumer and industrial electronics:

  • Flexible displays
  • Liquid crystal displays (LCDs)
  • Organic light-emitting diodes (OLEDs)
  • Organic photovoltaics (OPVs)
  • Printed circuit boards (PCBs)


  • Solar sails
  • Electrostatic dissipative coatings (e.g., for fighter jets)
  • Electromagnetic interference (EMI) shielding
  • Space antennas
  • Fresnel lenses
  • Reflectors
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Technology Details

What makes Kolon's CPI material better?

colorless filmCompared with other materials used as flexible substrates, Kolon's CPI material features many unique properties that make it an ideal alternative—inspiring a new generation of flexible electronics and other products.

  • Colorless
    The colorless quality of Kolon's CPI material makes it the only polyimide that can be used for flexible, transparent substrates while offering superior mechanical properties.
  • Capable of high-temperature processing
    While most available polymers are limited to processing at up to 180 °C, Kolon's CPI material offers a glass-transition temperature greater than 300 °C. This makes the material very well suited to conventional, high-temperature processing techniques.
  • No need for UV curing
    As OPVs and other solar-based applications increase in popularity, materials to accommodate them are likely to follow suit. While many substrates require an additional step of ultraviolet (UV) curing for use in such applications, Kolon's CPI material offers the potential to withstand 5 suns, making it ideal for use in OPVs and other associated products.
  • Ideal properties for use as a flexible substrate
    Kolon's CPI material offers many features making it ideal for flexible electronics. Among them, the material's capability for roll-to-roll processing, flexural endurance, and low dissipation factor provide the potential for superior performance.
  • Ideal surface for use as a polyimide film substrate
    Kolon's CPI material offers both superior surface hardness as well as ultra-smoothness. The material meets or exceeds the surface roughness and moisture absorption requirements for polyimide film substrates. It also demonstrates greater than H hardness at 1-kgf loading in pencil tests. In addition, 6 GPa of Young's modulus can be achieved, showing the material's excellent mechanical properties.

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The following specifications apply to Kolon's CPI material as of January 2016; however, additional R&D is currently underway.

Kolon CPI™ Technology
Tolerance: Temps, solvents
Glass transition temperature
>330 °C
Coefficient of thermal expansion (CTE)
<15 ppm/°C
Thermal shrinkage
Thermo-mechanical stability
3 hours at 20 – 150 °C
Chemical resistance
resistant to acids and some solvents and alkalis; coatings can enhance resistance
Surface properties
Average surface roughness
<10 nm
10 – 100 μm
Surface hardness
H~3H (pencil hardness test)
Barrier properties
Moisture barrier
<1% water absorption
Optical transparency
>88% (at 550 nm)
Dimensional stability
0.1% at 200 °C
Young’s modulus at 20 °C
3 – 6 GPa
Young’s modulus at 150 °C
~2 GPa
Tensile strength
130 – 250 MPa
Mechanically flexible?
yes 200K at R1 (folding test)
Electrical properties
Surface resistance
1.5x1016 Ω•cm
Dielectric properties
2.8 – 3.1
Other features
Radiation hard?
CPI varnish is coatable
Available in powder form?
Can be processed in organic solvents?

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Other Research

Research is ongoing to further improve Kolon's innovative, multipurpose CPI material, including studies designed to:

  • Enhance barrier properties
  • Enhance surface smoothness
  • Eliminate birefringence (i.e., double refraction)

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Commercial Opportunity

Kolon is making its innovative colorless polyimide material available for commercial use. You can:

  • Purchase customized rolls of Kolon CPI material up to 600 mm (23.6 inches) wide, taking advantage of Kolon's 1 million–m2 production capacity
  • Manufacture Kolon's cutting-edge CPI material as a joint venture with Kolon
  • Collaborate with Kolon's experts to enhance this unique material's barrier, surface smoothness, and birefringence properties

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For More Information

If you would like more information about this technology, please contact Sang-Kyun Kim (

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This technology is owned by Kolon Industries, Inc.