  Transparent conductors (TC's) combine the usually contraindicated properties
of electrical conductivity with optical transparency and are generally made by
starting with a transparent insulator and making it conductive via heavy
doping, an approach that generally faces severe 'doping bottlenecks'. We
propose a different idea for TC design-starting with a metallic conductor and
designing transparency by control of intrinsic interband transitions and
intraband plasmonic frequency. We identify the specific design principles for
three such prototypical intrinsic TC classes and then search computationally
for materials that satisfy them. Remarkably, one of the intrinsic TC,
Ag3Al22O34, is predicted also to be a prototype 3D compounds that manifest
natural 2D electron gas (2DEG) regions with very high electron density and
conductivity.
