The objective of this research is to investigate the materials requirements, device architecture, and processing for stretchable polymer thin film electronic devices. The research will demonstrate polymer light emitting diodes where the emissive region can be stretched by 50%. The project also investigates the mechanical compliancy of the devices with muscle contraction and for conforming onto uneven surfaces. The approach is to use stretchable polymer substrates, compliant transparent electrodes, and luminescent polymers, fabricate sandwiched structures by roll lamination, and create a p-i-n junction in a polymer thin film. The electroluminescent and photovoltaic properties of the devices will be characterized under various strain conditions to identify key issues for further enhancement of device performance. The project will lay the foundation for the fabrication of stretchable polymers for electronic devices. The project will provide fundamental knowledge on how large strains affect the property of p-i-n junction, the performance of the devices, and the interlayer adhesion. Polymer light emitting diodes will be demonstrated that are twice as efficient as light bulbs and can be stretched and contracted like muscle. The research may ultimately lead to new important products such as wearable devices, minimally invasive light sources for photodynamic therapy, and low-profile lighting devices. The products will have low cost and flexible form factors for broad market penetration and job creation. The project also offers a unique multidisciplinary research and education opportunity for graduate students, postdoctoral researchers, and undergraduates from materials creation and processing to device fabrication and testing.

Project Report

This project developed a novel technique to fabricate transparent electrodes comprising nanostructured conductive material inlaid in the surface layer of polymer substrate. The electrodes have high surface conductivity, high transparency, and low surface roughness, useful for the fabrication of thin film electronic devices. This is a new technology to replace indium tin oxide for reduced production cost and reduced toxicity. The fabrication process was further improved, and various formulations were developed to introduce intrinsic stretchability and/or high light extraction efficiency. The new conductor was formulated with various mechanical properties available to polymers, including mechanical flexibility, rubbery deformation, shape memory property, and self-healing. It was used to demonstrate a rubbery pressure sensor and sensor array. The new transparent conductor was used to fabricate flexible organic thin film electronic devices, including light emitting didoes and solar cells, with comparable or enhanced performance than control devices fabricated on the conventional indium tin oxide transparent conductor coated on glass. Elastomeric polymer light emitting devices were demonstrated that could be stretched, folded, twisted like a piece of rubber. The Youtube video showing a polymer LED being stretched was visited by 30,000 people in the first week posted online, and has received close to 73,418 in the first two months. Two invention patents were applied to the US Patent Office and PCT. The transparent conductor technology has been licensed to Polyradiant Corp. for commercialization. We demonstrated the first fully stretchable polymer light emitting device, or the elastomeric OLED that can be deform like a piece of rubber. The project also trained 3 graduate students, 3 postdoctoral fellows, 6 undergraduate students, 3 visiting graduate student, 6 high school student interns, who participated in the multidisciplinary project, received education and developed research skills with the project.

Project Start
Project End
Budget Start
2010-10-01
Budget End
2013-09-30
Support Year
Fiscal Year
2010
Total Cost
$319,999
Indirect Cost
Name
University of California Los Angeles
Department
Type
DUNS #
City
Los Angeles
State
CA
Country
United States
Zip Code
90095