期刊
ACS APPLIED MATERIALS & INTERFACES
卷 5, 期 10, 页码 4233-4238出版社
AMER CHEMICAL SOC
DOI: 10.1021/am400411a
关键词
nanocrystalline silicon; polymer nanocomposites; photoluminescence
资金
- NSF [CBET-1133135]
- DOE [DE-FG36-08G088160]
- NSF under MRSEC Grant [DMR-0819885]
- Directorate For Engineering
- Div Of Chem, Bioeng, Env, & Transp Sys [1133135] Funding Source: National Science Foundation
The photoluminescence (PL) of size-purified silicon nanocrystals is measured as a function of temperature and nanoparticle size for pure nanocrystal films and polydimethylsiloxane (PDMS) nanocomposites. The temperature dependence of the bandgap is the same for both sample types, being measurably different from that of bulk silicon because of quantum confinement. Our results also suggest weaker interparticle and environmental coupling in the nanocomposites, with enhanced PL and an unexpected dependence of lifetime on size for the pure nanocrystal films at low temperatures. We interpret these results through differences in the low temperature size dependence of the ensemble nonradiative equilibrium constants. The response of the PDMS nanocomposites provides a consistent measure of local temperature through intensity, lifetime, and wavelength in a polymer dispersed morphology suitable for biomedical applications, and we exploit this to fabricate a small-footprint fiber-optic cryothermometer. A comparison of the two sample types offers fundamental insight into the photoluminescent behavior of silicon nanocrystal ensembles.
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