One of the most exciting developments of the past two decades has been
the emergence of organic electronics. This term refers to the use of organic
materials as active layers in a variety of semiconductor devices. One example
is organic light emitting diodes, devices which emit visible light upon the
passage of current through an organic semiconductor film. These devices are
now commercially available in small format flat panel displays and are being
intensely developed for solid-state lighting. A second example is organic thin
film transistors, which control the flow of electricity in circuits and are being
developed for applications in smart tags and flat panel displays.
Concurrently, our need for sensors is ever increasing. Food safety, environmental
monitoring, medical diagnostics, and homeland security are all
areas that would benefit from the deployment of sensors and sensor networks.
Improvements would be useful or even required on multiple fronts, including
sensitivity and specificity, power consumption, portability, and cost. Organic
semiconductors offer many advantages in comparison with their inorganic
counterparts, which make them particularly attractive for sensor applications.
First, they can be deposited at or near room temperature on large area surfaces
and are compatible with mechanically flexible supports such as paper and
plastic. This enables their use in roll-to-roll fabrication techniques, which can
dramatically decrease manufacturing costs, an important attribute for disposable
sensors. Second, their properties can be tailored by means of chemical
synthesis. This includes electronic properties (such as energy gap and electron
affinity) but also properties such as surface energy. Of particular interest
for sensors is the ability to covalently attach biologically relevant moieties to
organic semiconductor molecules. Such hybrid materials have the potential to
lead to the fabrication of sensors with high sensitivity and specificity.