Multiple exciton generation (MEG) has been shown for quantum dots (QDs) in solution and in quantum dot solar cells. Direct conversion of solar energy to chemical fuels can also benefit from the enhanced conversion efficiency afforded by MEG. We present here a lead sulfide (PbS) QD photoelectrochemical cell that is able to drive a hydrogen evolution reaction with a peak external quantum efficiency (EQE) of over 100%, with the highest EQE at 114±1.3%. QD photoelectrodes with bandgap energies (E<sub>g</sub>) of 0.85, 0.92 and 1.08 eV all demonstrated clear MEG where absorption of a photon with at least 2.7xE<sub>g</sub> begins to produce more than one electron-hole pair per absorbed photon. Our results show that the extra carriers produced via MEG can be used to drive a chemical reaction with above unity quantum efficiency thus demonstrating a new direction in exploring high efficiency approaches for solar fuels.

Photoelectrochemical hydrogen evolution reaction with quantum yield exceeding 100% via MEG

253rd National Meeting (2017)

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