Organic Electronics

We have the interdisciplinary expertise and the facilities to create complete solutions that meet your important needs.

SRI International has a history of innovation in organic electronics and supporting technologies. We have developed organic light-emitting materials and devices (OLEDs), organic thin-film transistors (OTFTs), computational materials modeling, a MEMS platform for electronic sensing, flexible batteries, and molecularly imprinted polymers (MIPS). We have also developed inkjet printing of electronic circuits with conductive inks, printed displays, and electrochromics. We develop integrated solutions in materials research and development, device fabrication, systems characterization, testing and measurement, packaging, and prototyping.

SRI will work with you to:

• Develop new materials to meet your device requirements
• Integrate new materials into systems
• Characterize, test, and measure new systems

What can we do for you? Contact us.

SRI's subsidiary Sarnoff Corporation has developed organic electronics for more than 10 years. Sarnoff's pioneering work on active-matrix OLED displays resulted in the first AMOLED displays with self-compensating pixels, now a widely used approach. Sarnoff's development of organic thin-film transistors (OTFTs) at resulted in the first OTFT active-matrix liquid-crystal display. Current projects include combining OLED and OTFT technologies for active-matrix OLED displays on plastic substrates.

Materials Research

SRI scientists and engineers work together to solve materials-related issues. Interdisciplinary teams enable us to gain a unique understanding of how molecular structure relates to physical properties and facilitate the formation of innovative solutions. For example, targeting blue and white emissions from light-emitting polymers, our synthetic chemists have worked with our device engineers to develop several new materials. We have collaborated in the synthesis and fabrication of organic monomer- and polymer-based electro-chromic devices.

To fill the need for new organic electronic materials, our chemists use their synthetic and formulation experience with poly(phenylene vinylene)-, polythiophene-, polypyrrole-, and viologen-based systems. We can also provide expertise in the development of ceramics, composites, encapsulants, and sealants.

Systems Characterization, Testing, and Measurement

SRI performs fundamental research in optics and related disciplines, and applies optical and infrared technologies to the solution of practical problems. Technical specialties include the development of novel materials and prototype sensors. Facilities include labs for materials synthesis, materials characterization, and optical and infrared measurements. Staff have expertise in optics, electrical engineering, physics, materials science, and chemistry.

Microsystems Innovation Center

SRI's MicroSystems Innovation Center employs microelectromechanical systems (MEMS) fabrication processes and materials science to develop innovative
micro- and nanometer-scale structures, devices, and systems.

SRI and Sarnoff have performed tens of millions of dollars in contract R&D in the field of organic electronics. Information about some of our work follows.

Organic Light-Emitting Materials and Devices (OLEDs)

SRI's multidisciplinary team of chemical science and technology researchers and our Microsystems Innovation Center have several years of experience in development of luminescent polymers and novel device architectures. One such project is the polymeric cavity light emitting diode (CLED), which offers these key advantages:

• 3-5 times more efficient than traditional OLEDs since a CLED virtually has no optical loss
  
• Operation at 100 times higher current density (>100A/cm²) than traditional OLEDs
  
• Mechanically stronger and more durable than OLEDs
  
• A versatile fabrication process and large selection of materials to meet different needs, such as low-cost, high-brightness lighting applications and OLED displays

Organic Thin-Film Transistors (OTFTs)

Organic thin-film transistors (OTFTs) are gaining attention as a technology that enables electronic circuits and displays to be fabricated using low-cost processing on flexible plastic substrates. OTFTs have now been demonstrated with performance comparable to amorphous silicon TFTs, enabling a broad range of applications and motivating large research efforts. The entire OTFT fabrication process can be performed at temperatures of about 100°C or less, allowing great freedom in the choice of substrate materials.

Plastic substrates, in particular, allow circuits to be fabricated directly onto smart cards and inventory tags, which opens up the possibility of rapid, high-volume web processing. Rugged, flexible displays can also be built using an OTFT active-matrix on plastic, with liquid crystal or organic light-emitting diodes (OLEDs) as the electro-optic element. By combining flexible substrates with liquid deposition methods such as ink-jetting, electronics fabrication can be converted from relatively slow batch processing of substrate lots to high-speed continuous web processing.

The OTFT development team at SRI's subsidiary Sarnoff Corporation is advancing this technology through work in materials, processes, and system design. Sarnoff demonstrated the first OTFT active-matrix liquid-crystal display in 2001. This milestone represented the first video-capable AMLCD ever made on a plastic substrate.

As OTFT systems with higher levels of integration have been developed, such as analog and digital circuits and active-matrix OLED displays, Sarnoff's team has observed that OTFTs frequently exhibit hysteresis, i.e. memory effects, in their current-voltage characteristics. This can seriously reduce the performance of OTFT-based electronic systems. Sarnoff's pioneering work on the origins of OTFT hysteresis has shown that the hysteresis arises from long-lifetime electron traps in the organic semiconductor and, when a polymer film is used as a gate dielectric, slow polarization of the dielectric. Sarnoff is investigating the chemical origins of these effects, and is developing ways to reduce hysteresis and hysteresis-tolerant circuit design techniques.

Computational Materials Modeling

SRI has extensive experience in modeling optical and transport properties of organic materials and device structures. We have developed models to calculate exciton and biexciton properties in conjugated polymers. We have also constructed theoretical models and developed computational tools to describe charge transport in polymer films (carrier mobility and its dependence on electric field, temperature, and carrier density), in metal-organic-metal device structures (I-V characteristics), and in biological systems like DNA.

We have also established principles to model spin-dependent transport in organics and organic device structures and proposed organic spintronic devices including ultra-sensitive organic magnetometers and organic magnetic-field-effect transistors.

Flexible Batteries

SRI's Product Development Program has developed a printing process for rechargeable batteries and hybrid devices. We have demonstrated metal ceramic deposition by screen-printing, inkjet printing, and flexographic This printing process can be applied to the fabrication of custom-sized batteries which can be incorporated into a structure. SRI is also developing flexible, fiber-like lithium-rechargeable batteries.

MEMS Platform for Electronic Sensing

Organics are making an impact in the small microfabricated devices world. SRI is developing electronic sensors for chemical, biological, and physical variables including biowarfare agents, explosives, and magnetic fields. In these devices, organic materials are selected with specific interfacial and electronic properties to allow appropriate processing and functionalization of surfaces to prepare active sensing devices.

Conductive polymers like polyanilines, composites of non-conducting polycarbazones, and silicones are used to form orthogonal, ultra-low-power, tiny micro- and nano-sensors and sensor arrays for wireless electronic "noses" and targeted detection systems.

Molecularly Imprinted Polymers (MIPS)

Portable devices with high sensitivity and selectivity for the detection of precursors and hydrolysis products of chemical warfare agents are needed. SRI has developed surface acoustic wave (SAW) devices for the detection of thiodiethanol, a precursor and breakdown product of mustard gas, based on a palladium complex dispersed in poly(vinylpyrrolidone) (PVP). These devices are sensitive to a few ppb of thiodiethanol vapor in air. The sensor selectivity is tailored by proper selection of the palladium complex. SAW devices prepared from coatings containing a palladium-thiodiethanol complex have been shown to detect thiodiethanol selectively over thioxane.

On the other hand, SAW devices coated with palladium-PVP mixture detect both thiodiethanol and thioxane. Preliminary work on testing SAW devices containing a palladium-thioxane complex shows their enhanced selectivity for thioxane over thiodiethanol.

CONTACT US

For more information about SRI's capabilities in organic electronics, contact:

Dr. Christine Cuppoletti
SRI International
333 Ravenswood Avenue
Menlo Park, CA 94025
650.859.3987
christine.cuppoletti@sri.com