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Sensors 2017, 17(10), 2396;

Silicon Nanocrystals with pH-Sensitive Tunable Light Emission from Violet to Blue-Green

1,2,3,* , 1,2
Department of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
Jiangsu Provincial Engineering Laboratory for RF Integration and Micropackaging, Xinmofan Street 66, Nanjing 210003, China
Author to whom correspondence should be addressed.
Received: 4 September 2017 / Revised: 12 October 2017 / Accepted: 20 October 2017 / Published: 20 October 2017
(This article belongs to the Special Issue Solid-State pH Sensors)
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We fabricated a silicon nanocrystal (NC) suspension with visible, continuous, tunable light emission with pH sensitivity from violet to blue-green. Transmission electron microscopy (TEM) images and X-ray diffraction (XRD) pattern analysis exhibit the highly crystalline nanoparticles of silicon. Photoluminescence (PL) spectra and photoluminescence excitation (PLE) spectra at different pH values, such as 1, 3, 5, 7, 9, and 11, reveal the origins of light emission from the silicon NC suspension, which includes both the quantum confinement effect and surface bonding. The quantum confinement effect dominates the PL origins of silicon NCs, especially determining the tunability and the emission range of PL, while the surface bonding regulates the maximum peak center, full width at half maximum (FWHM), and offsets of PL peaks in response to the changing pH value. The peak fitting of PLE curves reveals one of the divided PLE peaks shifts towards a shorter wavelength when the pH value increases, which implies correspondence with the surface bonding between silicon NCs and hydrogen atoms or hydroxyl groups. The consequent detailed analysis of the PL spectra indicates that the surface bonding results in the transforming of the PL curves towards longer wavelengths with the increasing pH values, which is defined as the pH sensitivity of PL. These results suggest that the present silicon NCs with pH-sensitive tunable light emission could find promising potential applications as optical sources, bio-sensors, etc. View Full-Text
Keywords: silicon; nanocrystals; pH sensitive; photoluminescence silicon; nanocrystals; pH sensitive; photoluminescence

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Wang, J.; Guo, J.; Chen, J. Silicon Nanocrystals with pH-Sensitive Tunable Light Emission from Violet to Blue-Green. Sensors 2017, 17, 2396.

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