Organic electronics are a relatively new class of semiconductor devices which have the opportunity to enable advancements in display technology, solid state lighting, solar energy harvesting, and low cost ubiquitous computing and sensors.  Organic light-emitting devices (OLEDs) will find applications in flat panel displays and solid-state lighting, and can be manufactured from low cost printing methods such as ink jet or gravure printing. Organic Photovoltaics (OPVs) work similar to their inorganic counterparts.  However, their low cost will enable them to be used in large area panels to provide economical solar energy conversion devices.   Finally, Organic Field Effect Transistors (OFETs) offer transport mobilities which compare favorable with amorphous silicon, offering both a low cost and low temperature processible material which can be utilized for active matrix displays and low cost computing devices.

While much promise surrounds the continued advancements observed in organic electronics, critical issues must still be resolved in their overall reliability, especially in flexible applications.  Typical organic electronic devices utilize Indium Tin Oxide (ITO) as a hole injection or collection electrode.  ITO is both very expensive due to increasing demand from the flat panel and touch screen display markets, and it flexibility is limited due to the brittle nature of most oxides.  Both the potential degradation from mechanical deformation and the cost of ITO have given the impetus to develop new flexible, transparent electrode replacements for this material.

In addition to concerns over the electrode, organic electronics are typically very sensitive to oxygen and water vapor.  Thus, the development of transparent encapsulation films which possess effective water vapor transmission rates ~1mg/m2/day are necessary.  This limit is especially true when highly reactive low workfunction metal electrodes are utilized as the anode in OPVs and OLEDs.  While recent research has shown the ability to create ultrabarrier films using multilayer deposition of inorganic/organic films, work still needs to be performed on both integration with devices and understanding their performance under flexible deformation.

In this work, we are developing new flexible electrode materials from random networks of carbon nanotubes which can be printed onto a variety of substrates.  Understanding the workfunction, doping stability, and processing parameters on sheet resistance and transparency are of primary concern.  Sheet resistances on the order of 150 ohms/sq have been obtained with transparencies greater than 80%.  These sheet resistances are stable for bending radii as small as 5 mm.  The integration and evaluation of these electrodes into several devices as well as issues concerning their scale up to large area processing are currently being evaluated.

In addition to CNT electrodes, we are testing the performance of several multilayer thin films for encapsulation of organic electronics.  Films are deposited by PECVD and PVD techniques.  Permeability of the coatings is being measured using the calcium corrosion test.  The performance of the films is being related to the number of layers in the overall film, the mechanical properties, film stress, and defects.  Effective water vapor transmission rates <10ug/m2/day have been obtained. Integration with devices, tests under deformation, and long term reliability analysis is also underway.