Electrical structures which interact with light, such as
solar cells and optical sensors, generally employ electrodes to collect a
generated current (or to apply an external field), however, the electrode
designs commonly used suffer from a number of disadvantages. For example, the
wide spacing of electrodes in conventional solar cells, necessary to reduce
electrode shadowing and limit manufacturing cost, results in high series
resistance between the current generating areas and the current gathering
electrodes. This resistance leads to inefficient energy collection, especially
from the areas of the current generating structure that are farthest from the
electrodes. Packing the electrode structures more tightly fails to provide a
viable alternative because increasing the amount of electrode material will only
shield the current generating material from the incident radiation, thereby
significantly reducing efficiency and/or sensitivity. Accordingly, there exists
a need for electrode designs that can provide optimal electrical properties
while not blocking too much of the electrically active surface from light.
Researchers at Arizona State University have developed an
electrically active structure involving a self-assembling electrode comprising
dendritic metal elements formed on the exposed side of the structure. Due to its
multi-branched mixed-scale nature, the dendritic metal electrode can effectively
interact with a large area of the electrically active structure with minimal
resistance and minimal occlusion of underlying layers. Moreover, dendritic metal
structures can be relatively transparent when manufactured with nanoscale width
and thickness; such low dimensionality can be achieved at low cost using
self-assembly techniques.
Potential Applications
- Photovoltaic and Optoelectronic Devices (e.g. solar
cells, optical sensors, liquid crystal devices, etc.)
- Displays and touchscreen modules as transparent
electrodes
Benefits and Advantages
- Provides Both Reduced Resistance Current Collection and
Reduced Occlusion of Underlying Layers ? makes technology suitable for top
electrode use in electrical devices that photogenerate current (e.g. solar
cells, photodetectors); dendritic metal structure can effectively interact
with a large area of an electrically active structure without occluding a
substantial portion of the structure?s area
- Offers Relative Transparency through Nanoscale
Manufacturing ? low optical occlusion and high area coverage make it useful as
an electrode in field-based optical devices
- Allows Relatively Simple, Inexpensive Fabrication ? able
to fabricate devices using seld-assembly from a solid electrolyte (instead of
micro- or nanolithographic processes)