Hot-electron extraction from perovskite quantum dots for photovoltage enhancement

Abstract

Rapid energy loss from hot-carrier relaxation above the bandgap limits optoelectronic efficiency. A key unmet challenge for hot-carrier utilization is developing practical systems that combine long hot-carrier lifetimes in absorbers with efficient extraction in devices. Here, we fabricate CsPb1–xSnxI3 perovskite quantum dots (QDs) with long hot-carrier lifetimes under low pump intensity─critical for real applications. We also design Cs-doped TiO2 nanorod arrays as hot-carrier high-pass filters; their tuned band structure enables around 82% hot-electron extraction from surface-sensitized QDs, confirmed by visible/near-IR transient absorption and supported by DFT/NAMD calculations. Proof-of-concept hot-carrier solar cells based on these QDs-sensitized nanorod arrays show a 12% open-circuit voltage increase (up to 1.13 eV) vs normal cells, attributed to hot-carrier photocurrent (73% quantum efficiency at 400 nm vs 600 nm). Hot-carrier thermionic emission modeling validates results, providing a promising platform for photovoltaics beyond the Shockley–Queisser limit.