  Hot carrier solar cells allow potential efficiency close to the
thermodynamical limit in ideal conditions. However, the feasability of such
devices has not been clearly stated so far and only ideal cells were considered
in previous studies. Here we develop a model with realistic energy selective
contacts, carrier thermalization and absorptivity. The requirements in term of
contact selectivity is investigated, showing that semi-selective contacts are
not incompatible with high efficiencies. Candidates for absorbing material were
synthesized and the required thermalization properties are obtained. Specific
structures were designed to enhance absorption of concentrated sunlight in a
small material thickness, allowing high carrier density in the absorber.
