期刊
JOURNAL OF PHYSICAL CHEMISTRY C
卷 115, 期 41, 页码 20120-20127出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp205984m
关键词
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资金
- EU (PSYNANO)
- DFG [SFB 631 C3, GK 1240]
- Evonik Degussa S2B Nanotronics
- state of North Rhine-Westfalia
- Karl-Max von Bauernfeind-Verein of the TUM
- International Graduate School Material Science for Complex Interfaces (CompInt) of the TUM
- CRUP-DAAD
- FCT through the RNME - Pole University of Aveiro [REDE-1509-RME-2005]
- HybridSolar Project
- [PTDC-CTM-100468-2008]
- [PTDC-FIS-112885-2009]
- Fundação para a Ciência e a Tecnologia [PTDC/FIS/112885/2009] Funding Source: FCT
We have produced networks of surface-oxidized and hydrogen-terminated silicon nanocrystals (Si-NCs), both intrinsic and n-type doped, on flexible plastic foil from nanoparticle inks The charge transport in these networks was : comprehensively studied by means of time-dependent conductivity, steady-state current versus voltage characteristics, and steady-state photocurrent measurements as a function of incident light intensity. These measurements were complemented by surface chemistry and structural/morphological analysis from Fourier transform infrared spectroscopy and electron microscopy. Whereas H-terminated Si-NC networks function as semiconductors (both in air and in vacuum), where conductivity enhancement upon impurity doping and photoconductivity were observed, these characteristics are not present in networks of surface-oxidized Si-NCs. For both network types, the observation of a power law behavior for steady-state current versus voltage and a current decaying with time at constant bias indicate that charge transport is controlled by space-charge-limited current (involving trap states) via percolation paths through the networks. We have also monitored the evolution of the networks (photo)conductivity when the internanocrystal separating medium formed by Si-H bonds is progressively replaced by a native oxide upon exposure to air. Although a decrease in the (photo)conductivity is observed, the networks still behave as semiconductors even after a long-term air exposure. From an analysis of all (photo)current data, we deduce that in networks of oxidized Si-NCs inter-NC charge transfer requires the participation of oxide-related electronic states, whereas in H-terminated Si-NC networks direct inter-NC charge transfer plays a major role in the overall long-range conduction process.
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