Periodically nanoarchitectured photovoltaic solar cells and planar optical concentrators

Solar light received on earth is rich in photons in the 500-900-nm wavelength range. A photovoltaic solar cell is an optoelectronic device containing semiconductors that capture and absorb solar photons. Every absorbed photon creates an electron-hole pair (EHP). Electrons and holes are sent in opposite directions to generate an electric current. However, some electrons can recombine with holes to reduce the current. The design imperatives therefore are to enhance photon absorption, maximize the EHP generation rate, and minimize the EHP recombination rate. Periodic nanoarchitecture can assist in meeting these imperatives. The combination of nanoscale periodic gradation of the bandgap in the absorber layer of the solar cell and a periodically corrugated metallic backreflector shows promise. The same geometry with the absorber layer replaced by a periodically nonhomogeneous, nonabsorbing, dielectric layer can be efficacious for planar optical concentrators.