Indium Tin Oxide-Free Polymer Solar Cells: Toward Commercial Reality - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 194

Fig. 7 Schematic illustration of two upscaling geometries of solar cells: a a cross-section of a
monolithically integrated thin film module where width w is the active area that contributes to the
power generation and the interconnect area of width s is lost area. The dashed lines show the path
of current which is injected into the transparent electrode and then driven laterally to one edge of
the device where contact to the back metal electrode of the adjacent device is made. b Cross-
section of a standard cell (6 inch 2 ) using metalgrid/TC. These individual cells are stacked
adjacent to each other and serially connected in a long string. Area under the grid lines is lost area
and photogenerated current between the lines is conducted laterally over a short distance by the
TC film. c Maximum fraction of nominal efficiency as a function of the TC material figure of
merit for monolithic integration (lower green line) and for standard integration (upper blue line).
For monolithic integrations, achieving high module efficiencies will require r = a [ 1. Reproduced
from Ref. [ 12 ] with permission. 2013 RSC Publishing
3.1 Nanomaterials
3.1.1 Metal Nanogrids
Metal nanogrids are characterized by an array of periodic nanoscale metal grid
lines. For metal nanowire to be effective replacement of ITO, two design con-
siderations are important: (1) the grid lines width should be subwavelength to
provide sufficient visible transparency; and (2) the period of the mesh should be