Efficient Hot Electron Transfer in Quantum Dot-Sensitized Mesoporous Oxides at Room Temperature.
basic_science · Level V
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- Record sourced from PubMed, PMID 30039708.
- Also identified by DOI 10.1021/acs.nanolett.8b01981.
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Abstract
Hot carrier cooling processes represent one of the major efficiency losses in solar energy conversion. Losses associated with cooling can in principle be circumvented if hot carrier extraction toward selective contacts is faster than hot carrier cooling in the absorber (in so-called hot carrier solar cells). Previous work has demonstrated the possibility of hot electron extraction in quantum dot (QD)-sensitized systems, in particular, at low temperatures. Here we demonstrate a room-temperature hot electron transfer (HET) with up to unity quantum efficiency in strongly coupled PbS quantum dot-sensitized mesoporous SnO<sub>2</sub>. We show that the HET efficiency is determined by a kinetic competition between HET rate ( K<sub>HET</sub>) and the thermalization rate ( K<sub>TH</sub>) in the dots. K<sub>HET</sub> can be modulated by changing the excitation photon energy; K<sub>TH</sub> can be modified through the lattice temperature. DFT calculations demonstrate that the HET rate and efficiency are primarily determined by the density of the state (DoS) of QD and oxide. Our results provide not only a new way to achieve efficient hot electron transfer at room temperature but also new insights on the mechanism of HET and the means to control it.