  By harvesting a wider range of the solar spectrum, intermediate band solar
cells (IBSCs) can achieve efficiencies 50% higher than conventional
single-junction solar cells. For this, additional requirements are imposed to
the light-absorbing semiconductor, which must contain a collection of in-gap
levels, called intermediate band (IB), optically coupled to but thermally
decoupled from the valence and conduction bands (VB and CB).
Quantum-dot-in-perovskite (QDiP) solids, where inorganic quantum dots (QDs) are
embedded in a halide perovskite matrix, have been recently suggested as a
promising material platform for developing IBSCs. In this work, QDiP solids
with excellent morphological and structural quality and strong absorption and
emission related to the presence of in-gap QD levels are synthesized. With
them, QDiP-based IBSCs are fabricated and, by means of temperature-dependent
photocurrent measurements, it is shown that the IB is strongly thermally
decoupled from the valence and conduction bands. The activation energy of the
IB$\rightarrow$CB thermal escape of electrons is measured to be 204 meV,
resulting in the mitigation of this detrimental process even under
room-temperature operation, thus fulfilling the first mandatory requisite to
enable high-efficiency IBSCs.
