Carbon dots are unique fluorescent nanoparticles that can be made of many carbon sources. However, carbon source such as plastic is difficult to make carbon dots using simple synthesis procedure due to strong carbon bonds in the plastic material. The utilization of plastic source in carbon dots is a challenge. In this work, we used polyethylene in synthesis of citric acid carbon dots using simple microwave technique. We studied the effect of polyethylene addition on optical properties and surface energy level of carbon dots. We found that absorbance peak of core carbon dot was red shift and absorbance peak of surface level was blue shift due to addition of polyethylene. However, photoluminescence and timeresolved photoluminescence measurements showed that surface energy level was red shifted due to addition of polyethylene. The change of surface functional group was clearly observed using infra-red spectroscopy. Therefore, addition of polyethylene in carbon dots clearly modified surface energy level of carbon dots.
The comparison between two different bottom-up synthetic techniques had been prepared in order to synthesis the carbon dots (CD) from organic waste, i.e. the hydrothermal (HT) and microwave irradiation (MI) techniques. The CD were extracted from two different sources, i.e. from watermelon rind (wet organic waste) and peanut skin (dry organic waste). All of the products were characterized using spectroscopy characterization to determine their optical characteristics. It was obtained that all of the CD absorbing light in the UV region (around 300 nm) and emitting light in the visible light region (around 500 nm) which is called as photoluminescence (PL). The time-resolved PL (TRPL) was also observed within all of the products, which shows that they have TRPL around 3 to 4 ns, thus those CD categorized as fluorescence. Then, both CD from watermelon rind (WR) and peanut skin (PS) were examined using FTIR and it was obtained that both CD has carboxyl group content. After that, both products were also compared based on their performance as Fe3+ and Pb2+ sensors (1 nM–10-1 M with 10 interval). The best performance was achieved by PS CD, due to its consistency in optical characteristics degradations (negative degradation) due to PL-turn off sensor method with the regression of each optical characteristics (absorbance, PL, and TRPL) are 0.6542, 0.6567, and 0.6168.
We reported the fabrication of 1D photonic crystal structure and investigated its application for tuning colloidal CdSe
quantum dot emission. The photonic crystals was made by using sol-gel method and consists of TiO2 and SiO2
multilayers on glass substrate. The colloidal quantum dot is CdSe quantum dot with emission wavelength around 630
nm, which is similar to photonic band gap of fabricated photonic crystals. The quantum dot was dropped and dried on the
opposite side of photonic crystals. We measured angle dependence of transmission of photonic crystal and angle
dependence photoluminescence of quantum dot emission. We found that quantum dot emission was influenced by
excitation angle ; therefore photonic crystals can be useful for tuning the emission of quantum dot. We have confirmed
that the angle dependence photoluminescence of quantum dot is significantly related to photonic band gap of photonic
crystal. This work leads to future application of photonic crystal on quantum dot emission such as quantum dot lasing.
Conference Committee Involvement (1)
Third International Seminar on Photonics, Optics, and Its Applications (ISPhOA 2018)
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