Multiple exciton generation for photoelectrochemical hydrogen evolution reactions with quantum yields exceeding 100%

作者：Yan, Yong^*; Crisp, Ryan W.; Gu, Jing; Chernomordik, Boris D.; Pach, Gregory F.; Marshall, Ashley R.; Turner, John A.; Beard, Matthew C.

来源：Nature Energy, 2017, 2(5): 17052.

DOI：10.1038/nenergy.2017.52

• DOT SOLAR-CELL
• CARRIER MULTIPLICATION
• SEMICONDUCTOR NANOCRYSTALS
• WATER REDUCTION
• VISIBLE-LIGHT
• EFFICIENCY
• 120-PERCENT
• CATALYST
• PBS
• H-2

Multiple exciton generation (MEG) in quantum dots (QDs) has the potential to greatly increase the power conversion efficiency in solar cells and in solar-fuel production. During the MEG process, two electron-hole pairs (excitons) are created from the absorption of one high-energy photon, bypassing hot-carrier cooling via phonon emission. Here we demonstrate that extra carriers produced via MEG can be used to drive a chemical reaction with quantum efficiency above 100%. We developed a lead sulfide (PbS) QD photoelectrochemical cell that is able to drive hydrogen evolution from aqueous Na2S solution with a peak external quantum efficiency exceeding 100%. QD photoelectrodes that were measured all demonstrated MEG when the incident photon energy was larger than 2.7 times the bandgap energy. Our results demonstrate a new direction in exploring high-efficiency approaches to solar fuels.

• 出版日期2017-5