Thermophotovoltaic Cells Based on Low-Bandgap Compounds

High efficiency TPV GaSb and Ge based cells fabricated by a non-toxic and inexpensive Zn-diffusion technique have been developed. GaSb based cells optimised for operation with solar powered photon emitter allowed increasing the efficiencies up to 27-28% at black body temperature > 2000 K assuming 90% reflection of sub-bandgap photons. Combination of the MOCVD technique or LPE growth and Zn diffusion from the gas phase allows fabricating Ge photocells on the base of the GaAs/Ge heterostructures, which are characterized by high photocurrent and open circuit voltage values. Efficiencies of 13% were obtained in GaAs/Ge TPV cells under the black-body (1700-2100 K) irradiation assuming the achieved 90% reflection of sub-bandgap photons.