Hot carrier extraction from 2D semiconductor photoelectrodes
arXiv:2210.13588 · doi:10.1073/pnas.2220333120
Abstract
Hot carrier-based energy conversion systems could double the efficiency of conventional solar energy technology or drive photochemical reactions that would not be possible using fully thermalized, ``cool'' carriers, but current strategies require expensive multi-junction architectures. Using an unprecedented combination of photoelectrochemical and in situ transient absorption spectroscopy measurements, we demonstrate ultrafast (<50 fs) hot exciton and free carrier extraction under applied bias in a proof-of-concept photoelectrochemical solar cell made from earth-abundant and potentially inexpensive monolayer (ML) MoS2. Our approach facilitates ultrathin 7Åcharge transport distances over 1 cm^2 areas by intimately coupling ML-MoS2 to an electron-selective solid contact and a hole-selective electrolyte contact. Our theoretical investigations of the spatial distribution of exciton states suggest greater electronic coupling between hot exciton states located on peripheral S atoms and neighboring contacts likely facilitates ultrafast charge transfer. Our work delineates future 2D semiconductor design strategies for practical implementation in ultrathin photovoltaic and solar fuels applications.
arXiv comment6 pages, 3 figures main text; 6 pages, 8 figures, 1 table, 57 refs. appendices
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