TY  - JOUR
T1  - Synthesis and Optical Characterization of Colloidal CdSe Quantum Dots Nucleated for A Long Time at High Temperature
TT  - Yüksek Sıcaklıkta Uzun Bir Süre Çekirdekleştirilen Kolloidal CdSe Kuantum Noktalarının Sentezi ve Optik Karakterizasyonu
AU  - Allahverdi, Çağdaş
PY  - 2019
DA  - May
DO  - 10.21541/apjes.389919
JF  - Academic Platform - Journal of Engineering and Science
JO  - APJES
PB  - Akademik Perspektif Derneği
WT  - DergiPark
SN  - 2147-4575
SP  - 229
EP  - 236
VL  - 7
IS  - 2
LA  - en
AB  - Colloidal CdSe quantum dots were nucleated at about 300oC for 15 s and growth at 272oC up to 245 min in non-coordinatingsolvent octadecene by using hot-injection technique. Stearic acid was used as a capping agent in the synthesis of CdSe quantumdots. The nucleation time used in this study was considerably longer than those in the literature and its effect on the opticalproperties was examined. The first excitonic absorption and corresponding recombination peaks were observed in their opticalabsorption and photoluminescence spectra, respectively. The value of Stokes shift changed up to 70 meV. A peak and shoulderstructure was obtained in the optical absorption and photoluminescence spectra of the sample growth for 20 min. It was indicatedthat CdSe quantum dots which are nucleated at high temperature for a sufficiently long period may have double size distribution.The images of CdSe quantum dots were obtained via transmission electron microscopy. Their images were processed with theimage processing program ImageJ. The average size of CdSe quantum dots growth for 12 min was found as 2.63 nm. The sizedispersion increased 4.6 times with respect to that of the monodisperse quantum dots. The X-ray energy transition peaks belongto Cd and Se elements were observed in their energy dispersive X-ray spectra. Symmetric and asymmetric vibrational modes ofstearic acid molecules capping these quantum dots were determined at about 2848 cm-1and 2914 cm-1, respectively, by usingFourier transform infrared spectroscopy.
KW  - optical absorption
KW  - photoluminescence
KW  - Fourier transform infrared spectroscopy
KW  - transmission electron microscopy
KW  - : CdSe quantum dots
KW  - transmission electron microscopy
N2  - Kolloidal CdSe kuantum noktaları, koordine olmayan oktadesen çözücü içerisinde sıcak-enjeksiyon tekniği kullanılarak yaklaşık300oC’de 15 s çekirdekleştirildi ve 272oC’de 245 dakikaya kadar büyütüldü. CdSe kuantum noktalarının sentezinde stearik asitbir kaplama ajanı olarak kullanıldı. Bu çalışmada kullanılan çekirdekleşme zamanı literatürdekilere göre oldukça uzundu veoptik özelliklere olan etkisi incelendi. Birinci eksiton soğurma ve karşılık gelen rekombinasyon tepeleri, sırasıyla, optik soğurmave fotolüminesans spektrumlarında gözlendi. Stokes kayma değeri 70 meV’ye kadar değişti. 20 dakika için büyütülen numuneninoptik soğurma ve fotolüminesans spektrumlarında bir tepe ve omuz yapısı elde edildi. Yüksek sıcaklık altında yeterince uzun birsürede çekirdekleştirilen bu kuantum noktalarının çift büyüklük dağılımına sahip olabileceği gösterildi. CdSe kuantumnoktalarının görüntüleri geçirgenlik elektron mikroskopi vasıtasıyla elde edildi. Resimleri, ImageJ görüntü işleme programı ileişlendi. 12 dakika büyütülen CdSe kuantum noktalarının ortalama büyüklüğü 2.63 nm olarak bulundu. Büyüklük dağılımı tekildağılımlı kuantum noktalarınkine nazaran 4.6 kat arttı. Cd ve Se elementlerine ait X-ışınları enerji geçiş tepeleri enerji dağılımlıX-ışınları spektrumlarında gözlendi. Bu kuantum noktalarını saran stearik asit moleküllerinin simetrik ve asimetrik tireşimmodları Fourier dönüşümlü kızıl ötesi spektroskopi kullanılarak, sırasıyla, 2848 cm-1 ve 2914 cm-1civarında belirlendi.
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UR  - https://doi.org/10.21541/apjes.389919
L1  - https://dergipark.org.tr/en/download/article-file/665846
ER  -