Open AccessCarrier transport characteristics in CdSe/CdS/Thioglycolic acid ligand quantum dots with a core-shell structure
Author(s) -
薛振杰,
李葵英,
孙振平
Publication year - 2013
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.62.066801
Subject(s) - quantum dot , thioglycolic acid , materials science , high resolution transmission electron microscopy , surface photovoltage , band gap , grain size , nanocrystal , potential well , photoluminescence , analytical chemistry (journal) , transmission electron microscopy , nanotechnology , optoelectronics , spectroscopy , chemistry , physics , composite material , organic chemistry , chromatography , quantum mechanics
In the present paper, we synthesize CdSe quantum dots (QDs) that are stabilized by thioglycolic acid according to the water-phase synthesis. The X-ray diffraction and HRTEM results confirm that the samples prepared each possess a sphalerite structure. The EDS and FT-IR spectra of the samples show that a core-shell structure is formed between the CdSe nanoparticles and the ligand. The fine band structures and the characteristics of the surface states in a connection with the structures are identified by the surface photovoltage (SPV) spectrum of the samples. Two SPV response peaks, located at 475 nm (2.61 eV) and 400 nm (3.1 eV), are closely related to the band-band transitions of the core-CdSe and the shell-CdS, respectively; the SPV response at 370 nm (3.35 eV) is correlated with the n → π* transition between the hydroxyl and sulfydryl (or hydroxyl). It is because of an obvious quantum size effect of the samples that both PL line broadens and SPV response intensity increases with the decrease of the grain size of the sample. The change trend of the surface photoacoustic signal intensity is contrary to that of the SPV response intensity of the samples synthesized at varying pH. Moreover, the fine band structures at surfaces and grain boundaries of CdSe QDs prepared are probed by the SPV spectra of the samples at varying pH values. The relationship between the grain size and the photo-generated carrier transport behavior is discussed according to the detected EFISPV results of the QDs.