Sandwiched confinement of quantum dots in graphene matrix for efficient electron transfer and photocurrent production.

Nan Zhu,Kaibo Zheng,Jens Ulstrup,Dörthe Haase,Stefan Carlson,Mohamed Abdellah,Tõnu Pullerits,Qijin Chi,Khadga J Karki,Qiushi Zhu,Sophie E Canton,Karel Žídek

doi:10.1038/srep09860

Nan Zhu, Kaibo Zheng + Show 10 more

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https://doi.org/10.1038/srep09860

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Quantum dots (QDs) and graphene are both promising materials for the development of new-generation optoelectronic devices. Towards this end, synergic assembly of these two building blocks is a key step but remains a challenge. Here, we show a one-step strategy for organizing QDs in a graphene matrix via interfacial self-assembly, leading to the formation of sandwiched hybrid QD-graphene nanofilms. We have explored structural features, electron transfer kinetics and photocurrent generation capacity of such hybrid nanofilms using a wide variety of advanced techniques. Graphene nanosheets interlink QDs and significantly improve electronic coupling, resulting in fast electron transfer from photoexcited QDs to graphene with a rate constant of 1.3 × 109 s−1. Efficient electron transfer dramatically enhances photocurrent generation in a liquid-junction QD-sensitized solar cell where the hybrid nanofilm acts as a photoanode. We thereby demonstrate a cost-effective method to construct large-area QD-graphene hybrid nanofilms with straightforward scale-up potential for optoelectronic applications.

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Separation proceeds via interfacial electron transfer (ET) or hole transfer (HT) from quantum dot (QD) to the electrodes
Following the synthesis and morphologic characterization of the QD-reduced graphene oxide (RGO) hybrid films, we studied their structures in detail
Large-area QD containing thin films are highly desirable for the fabrication of QD-sensitized solar cells and other QD based optoelectronic devices

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Separation proceeds via interfacial electron transfer (ET) or hole transfer (HT) from QDs to the electrodes. The development of new electrode materials, synergic assembly of the two key components, and understanding of charge transport mechanisms are the central issues towards realizing optimal design and construction of high-performance QD based solar power conversion systems. Graphene as a wonder material has emerged at an unprecedented pace over the past decade[26,27,28] This material has continued to develop as an effective alternative to many conventional optoelectronic, photonic, plasmonic and energy materials. A state-of-the-art study recently by Konstantatos and co-workers has clearly demonstrated that hybrid graphene-QD films enable achieving an ultrahigh gain of electrons per photon[38], which is expected to significantly promote the development of new-generation phototransistors based on hybrid QD-graphene materials.

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