Room Temperature Operation of a Quantum Ratchet Intermediate Band Solar Cell

An intermediate band solar cell which generates photocurrent due to sequential absorption of two sub‐bandgap photons at temperatures up to 300 K was realized. The intermediate band is comprised of a “quantum ratchet” semiconductor nanostructure which is designed to store the photoelectron in a long‐lived state that allows for efficient optical re‐absorption; it incorporates a potential barrier designed to both increase the confinement of electrons and reduce thermal escape. This leads to extended electron lifetimes in the ratchet state and room temperature operation. At low temperature (≈12 K), electrons exhibit a ratchet state lifetime of τ RB > 100 s, representing an increase by a factor of ≈10 7 over a device without the barrier.