第30卷第7期 2015年7月
Article ID: 1000-324X(2015)07-0774-05
无机材料学报 Journal of Inorganic Materials
Vol. 30 No. 7 Jul.,2015
DOI:10.15541/jim20140624
FacileHydrothermalSvnthesisofOil-SolublePbSeQuantumDots YANG Feng-Jiu, LU Meng-Chen, ZHANG Xin, ZHANG Yan, WANG Lian-Jun, JIANG Wan
(State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620. China)
Abstract: Oil-soluble PbSe quantum dots (QDs) with uniform morphology and narrow size distribution were ob-tained via a facile hydrothermal approach. The cubic PbSe QDs with nearly spherical shape and average diameter of(4.0 ± 0.5) nm were obtained. The as-synthesized PbSe QDs showed a strong and a relatively narrow band edge emis- on jo aeordde ( xe e e p n es e pe s e oea dand ea a r rors The photoluminescence (PL) spectra moved to low energy region and FWHM became broad when the reaction time extended and the synthesis temperature increased. The PL spectra exhibited less intense and well defined features at long wavelength which were ascribed to low energy transitions as varying Pb/S molar ratios. In addition, the defect luminescence of PbSe QDs became more obvious with the synthesis temperatures and Pb/S molar ratios increasing The PL spectra of PbSe QDs shifted to long wavelength (low energy region), because small particles coalesced into form large particles during reaction, which was in agreement with the Ostwald ripening principle. The defects of PbSe QDs may result from thermodynamically instable and lower densities of capped oleic acid.
Key words: hydrothermal approach; PbSe quantum dots; semiconductor; photoluminescence
Semiconductor quantum dots (QDs) have attracted numerous attention due to their unique size-dependent energy band structures for optoelectronic properties, which are greatly different from the corresponding bulk materials and molecular(i-2)]. There is a great ap-plication prospect for them in lighting emitting diodes(LEDs), optical switches, solar cells, lasers and bio-logical labeling/3-7). Furthermore, quantum size effects of nanocrystals could be tuned from the low energy to high energy region both in optical absorption and emission spectra. These phenomena have been exten-sively studied in size controlled and monodisperse II-VI semiconductor quantum dots (CdS, CdSe and CdTe)[8-10), Similarly, considerable efforts have been invested in synthesizing high quality semiconductor QDs over the past two decadesli-14]
In contrast to typical semiconductor QDs in IV-VI groups, lead chalcogenides exhibite similar the size dependent properties to the cadmium system as direct energy gap semiconductors in the bulk phase, however, they have a narrower band gap energies (0.41 eV for
PbS and 0.28 eV for PbSe) and a larger excitation Bohr radius (1846 nm) to cadmium systems (410 nm). Therefore, extremely strong quantum size effects could be obtained in larger size particles compared to other semiconductor QDs(15]. Nevertheless, the pro-ductionofleadchalcogenidessemiconductor nanocrystals (PbS, PbSe and PbTe) has been explored in recent years16-i7]A versatile liquid-phase prepara-tion for PbSe colloidal QDs was first reported by Murray, et al(18]. Yu, et a/(17] reported synthesis of PbSe QDs in a non-coordinating solvent. The compo-sition and size dependent effects extinction coefficient for colloidal PbSe QDs was reported by Moreels(19) Primera-Pedrozo and co-workers reported that the PbSe QDs was synthesized in aqueous solution and interacted with ligands at room temperature,which could remain stable in two months under normal con+ dition(20). The PbSe QDs could be used in biomedical field because the selected ligands were water soluble. The PbSe QDs synthesized in the inorganic substrate was recently reported by Ma/21), Cheng/22] and their
Received date: 2014-12-03; Modified date: 2015-02-28; Published online: 2015-04-10
Foundation item: National Natural Science Foundation of China (51272042, 51432004); Innovation Foundation of Master Degree
Thesis of Donghua University (EG2014008)
Biography : YANG Feng-Jiu (1989-), male, candidate of master degree. E-mail: yangfengjiu@163.com Corresponding author: WANG Lian-Jun, professor. E-mail: wanglj@dhu.edu.cn