Cyrus Tang Center for Sensor Materials and Applications

Hangzhou, China

Cyrus Tang Center for Sensor Materials and Applications

Hangzhou, China

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Liang X.,Cyrus Tang Center for Sensor Materials and Applications | Yi Q.,Cyrus Tang Center for Sensor Materials and Applications | Bai S.,Cyrus Tang Center for Sensor Materials and Applications | Dai X.,Cyrus Tang Center for Sensor Materials and Applications | And 7 more authors.
Nano Letters | Year: 2014

We demonstrate a facile and general strategy based on ligand protection for the synthesis of unstable colloidal nanocrystals by using the synthesis of pure p-type NiO nanocrystals as an example. We find that the introduction of lithium stearate, which is stable in the reaction system and capable of binding to the surface of NiO oxide nanocrystals, can effectively suppress the reactivity of NiO nanocrystals and thus prevent their in situ reduction into Ni. The resulting p-type NiO nanocrystals, a highly demanded hole-transporting and electron-blocking material, are applied to the fabrication of organic solar cells and polymer light-emitting diodes, demonstrating their great potential as an interfacial layer for low-cost and large-area, solution-processed optoelectronic devices. © 2014 American Chemical Society.


Liang X.,Cyrus Tang Center for Sensor Materials and Applications | Ren Y.,Cyrus Tang Center for Sensor Materials and Applications | Bai S.,Cyrus Tang Center for Sensor Materials and Applications | Zhang N.,Cyrus Tang Center for Sensor Materials and Applications | And 11 more authors.
Chemistry of Materials | Year: 2014

Transition metal oxides are widely used in solution-processed optoelectronic devices as charge-transporting interlayers to improve contact properties and device performances. Here we show that the work function of oxide nanocrystal thin films, one of the most important parameters for charge-transporting interlayers, is readily tuned by rational design of material synthesis. Mechanism studies reveal that the combination of employing the reverse-injection approach and using zinc stearate and indium 2-ethylhexanoate as the cationic precursors ensures both controlled reaction pathways and balanced relative dopant-host precursor reactivity and hence high-quality indium doped zinc oxide nanocrystals. We find that the empirical rule of relative Lewis acidity fails to predict the relative reactivity of the cationic precursors and quantitative measurements are obligatory. The successful incorporation of indium dopants into host oxide nanocrystals accompanied by the generation of high density of free electrons leads to oxide thin films with lower work function. Polymer light-emitting diodes with electron-transporting interlayers based on the indium doped zinc oxide nanocrystals exhibit improved electron-injection properties and enhanced device characteristics, i.e., lower turn-on voltage, higher maximum luminance, and higher efficiency. Our study is an excellent example that new understanding on the chemical kinetics of doped nanocrystals leads to rational design of synthetic protocols and materials with tailored electronic properties, providing benefits for their optoelectronic applications. © 2014 American Chemical Society.

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