Surface passivation by l-arginine and enhanced optical properties of CdS quantum dots co-doped with Nd3+–Li+

Journal of Nanostructure in Chemistry, Mar 2015

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 co-doped 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.

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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 - 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)


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S. S. Talwatkar, A. L. Sunatkari, Y. S. Tamgadge, V. G. Pahurkar, G. G. Muley. Surface passivation by l-arginine and enhanced optical properties of CdS quantum dots co-doped with Nd3+–Li+, Journal of Nanostructure in Chemistry, 2015, pp. 205-212, Volume 5, Issue 2, DOI: 10.1007/s40097-015-0151-4