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论文类型：期刊论文

发表时间：2019-08-13

发表刊物：PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA

收录刊物：SCIE、PubMed

卷号：116

期号：33

页面范围：16198-16203

ISSN号：0027-8424

关键字：photoelectrochemical cell; metal oxide electrode; bichromophoric dyad |; excited-state transitions

摘要：The direction of electron flow in molecular optoelectronic devices is dictated by charge transfer between a molecular excited state and an underlying conductor or semiconductor. For those devices, controlling the direction and reversibility of electron flow is a major challenge. We describe here a single-molecule photodiode. It is based on an internally conjugated, bichromophoric dyad with chemically linked (porphyrinato) zinc(II) and bis(terpyridyl) ruthenium(II) groups. On nanocrystalline, degenerately doped indium tin oxide electrodes, the dyad exhibits distinct frequency-dependent, charge-transfer characters. Variations in the light source between red-light (similar to 1.9 eV) and blue-light (similar to 2.7 eV) excitation for the integrated photodiode result in switching of photocurrents between cathodic and anodic. The origin of the excitation frequency-dependent photocurrents lies in the electronic structure of the chromophore excited states, as shown by the results of theoretical calculations, laser flash photolysis, and steady-state spectrophotometric measurements.