Background

Conventional transparent conductive materials, such as sputtered metal oxides (e.g. ITO, FTO) or polymers (PEDOT:PSS), require synthesis temperatures over 120 ˚C. Some flexible conductive composites can be fabricated at lower temperatures, however conductive media is typically deposited over the film, providing only in-plan conductivity. Our technology allows to synthesize at room temperature free-standing or semi-bonded flexible films with high optical transparency and high out-of-plane conductivity.

Technology Overview

The University of Hawaii (UH) has developed a new composite integrating multi-functionalities such as corrosion resistance, lightweight and flexibility as well as tunable optoelectronics. Unlike most conductive flexible polymers, where media are coated on top providing only in-plane conductivity, the transparent-conductive-flexible composites (TCFC) innovate by allowing simultaneously optical transparency and out-of-plane electrical conductivity. This unique characteristic is permitted by highly conductive spheres protruding out of a transparent non-conductive polymer (Figure 1.a and b). TCFCs can be formed by pressing a particle/polymer mix between two substrates. Depending on the surface treatment pre-applied to the substrates, TCFCs can be either i) fully liberated to create free-standing films (Figure 1.b and c), ii) remain bonded to only one substrate or iii) permanently bonded to both substrates ().

Stage of Development

UH has thus far been successful in fabricating proof-of-concept free-standing TCFCs using 50 micron silver particles embedded in a polymer. These free-standing films possess both high optical transmittance ( Figure 2.a ) and high out-of-plane conductivity (R=0.27 Ω.cm², Figure 2b ), significantly outperforming commercially available F:SnO₂/glass (FTO) substrates. The fact that we are able to measure high out-of-plane conductivity demonstrates that the particles of the free-standing layer protrude from the polymer matrix.

Benefits

Antistatic
Corrosion resistance
Flexible
Free standing
Lightweight
Room temperature processing
Semi-bonded
Tunable optoelectronics

Applications

UH’s disruptive new technology has great potentials in many applications where materials with good conformability to shapes, resistance against corrosion and tunable optoelectronic properties are necessary. In in-mold electronic and photovoltaic applications, TCFCs can be used to isolate on-board electronic circuits or devices from atmospheric effects while allowing electrical access to the contacts. In electrochemical power systems (batteries, fuel cells. electrolyzers), TCFCs can be applied as barriers against degradation and the nature of the particles modified to be selective to specific electrochemical reactions. Finally, TCFCs can be used to isolate metallic parts from corrosive environments while preventing electrostatic buildup.

Transparent Free-Standing Thin Film Composites with Tunable Out-of-plan Electrical Conductivity

Patents

IP Status

Seeking