Surface passivation by l-arginine and enhanced optical properties of CdS quantum dots co-doped with Nd3+–Li+
Surface passivation by L-arginine and enhanced optical properties of CdS quantum dots co-doped with Nd3+-Li+
S. S. Talwatkar 0 1 2 3
A. L. Sunatkari 0 1 2 3
Y. S. Tamgadge 0 1 2 3
V. G. Pahurkar 0 1 2 3
G. G. Muley 0 1 2 3
0 Y. S. Tamgadge Department of Physics, Shri Shivaji Arts, Commerce and Science College , Akola 444003, Maharashtra , India
1 A. L. Sunatkari Department of Physics, Siddharth College of Arts , Science and Commerce, Fort, Mumbai 400001, Maharashtra , India
2 S. S. Talwatkar Department of Physics, N. G. Aacharya and D. K. Marathe College of Arts , Science and Commerce, Chembur, Mumbai 400071, Maharashtra , India
3 V. G. Pahurkar G. G. Muley (&) Department of Physics, Sant Gadge Baba Amravati University , Amravati 444602, Maharashtra , India
L-Arginine-passivated Nd3? and Li? co-doped CdS quantum dots (QDs) were synthesized by chemical precipitation method. Ultraviolet-visible absorption spectra of prepared QDs show absorption in the range of 477-450 nm indicating huge blue shift in energy band gap as compared to the bulk CdS due to quantum confinement effect. The optical band gap is found increasing from 2.44 to 2.97 eV as the doping concentration increased from 1 to 5 wt%. Photoluminescence spectra showed that codoped CdS QDs are highly luminescent and emit multiple intense violet (362, 371, 385, 395 nm) and blue (422, 445, 456 and 465 nm) coloured peaks with increasing intensity with co-dopant concentration. Fourier transform infrared study confirmed the interaction between CdS nanoparticles and L-arginine ligands. The structural and morphological study revealed the formation of orthorhombic crystal structure. The size of CdS QDs, as analysed by X-ray diffraction and high-resolution transmission electron microscopy, is found reducing with co-dopant concentration. The energy dispersive X-ray analysis shows no impurities present except dopants indicating high purity of the prepared samples. Based on the results, we proposed that this material is a new class of luminescent material suitable for optoelectronics devices' application, especially in light emitting devices, electroluminescent devices and display devices.
CdS quantum dot; Nd3?-Li? co-doping; L-Arginine capping; Blue-violet emission
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The last two decades have witnessed a tremendous growth
and improvisation in investigating and developing
semiconductor nanoparticles in the field of basic and applied
research. The semiconducting nanoparticles are of great
importance due to their unique physical and chemical
properties. The structural aspects and optical properties
such as photoconductivity and photoluminescence of
nanoparticles are substantially different from their bulk
counterparts attributed to the quantum confinement effect
and large surface to volume ratio of atoms. Group IIIV
semiconductor nanoparticles have wide applications in
optoelectronics, photonics, solar cell, photo-detector, laser,
light emitting diodes, and high-density magnetic
information storage [17]. Among the chalcogenide materials, CdS
is widely investigated due to its intrinsic direct band gap of
2.42 eV at room temperature, which can be exploited in
potential device applications involving bio-imaging,
heterogeneous photo catalysis, nonlinear optics and many
more [811].
Since Bhargava and co-worker [12] reported significant
enhancement in photoluminescence in Mn2? doped ZnS
nanoparticles, doping method has been widely used to alter
the physical and chemical properties of CdS quantum dots
(QDs). Dopant ions interact with host atoms and may bring
electronic state within the band gap rendering peculiar
properties to the material [13, 14]. CdS QDs with various
metal dopants of different concentrations and size
controlling capping agents have studied for their tunable band
gap, size-dependant optical properties, chemical stability,
and easy preparation techniques [15]. The location of
dopant in the host material produces changes in properties
of CdS QDs. Transition metals such as cobalt, manganese,
copper and nickel-doped CdS nanoparticles have widely
attracted the scientific attention due to their unique optical
properties and their potentiality for various applications
[1620]. In the recent years, researchers have diverted their
attention to co-doped CdS QDs with dopant combinations
such as Ni2?Mn2?, Pb2?Cu2?, Cu?Cu2?, Co2?Cu2?,
CuAl, Mn2?Eu3?, Cu2?In3?, Li?RE3? and Cu2?
RE3? (RE-rare earth) to explore the possibility of
enhanced photoluminescence [2126]. In addition, surface
passivation also plays a vital role in the enhancement of
optical properties, especially photoluminescence.
Numerous reports are available on the influence of surface
passivation on improving linear optical properties of CdS QDs
[27]. Amino acids are inherently compatible, and one of the
common amino acids is L-arginine, which has zwitterionic
structure. Hence, functionalization of CdS QDs with
L-arginine molecule highly facilitates the interaction of
nanoparticles with functional g (...truncated)