Unstrained PbSe/CdSe core shell nanostructures for broad band absorber and narrow band IR emitters
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Unstrained PbSe/CdSe core shell nanostructures for broad band absorber and narrow band IR emitters Nayandeep Mishra1 · K. K. Nishad2 · Varsha R. Mehto3 · Deepshikha Rathore4 · R. K. Pandey5 Received: 10 December 2017 / Accepted: 7 April 2018 © Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract The purpose of this work is to establish structural, morphological and optical properties of PbSe quantum dots (QDs) and PbSe/CdSe core/shell nanostructures (C/S NSs) for application as broad band absorber and narrow band emitters. These NSs were synthesized using chemical bath deposition technique. The structural properties were studied using X-ray diffraction technique with Rietveld refinement and transmission electron microscopy (TEM). The surface morphology of synthesized thin film was established using atomic force microscopy (AFM) and scanning electron microscope (SEM). The optical properties were explained using UV–Vis absorption and photoluminescence (PL) spectroscopy with electron–hole recombination process. A comparison of estimated crystallite size from XRD, high resolution AFM and TEM images was resulted in good agreement as ~ 6.2 ± 0.5 and ~ 6.5 ± 0.5 nm for PbSe QDs and PbSe/CdSe C/S NSs respectively.These obtained properties of self-assembled PbSe/CdSe C/S NSs are expected to be useful in the development of broad band absorber and narrowband IR emitters and solar cells.
1 Introduction Semiconductor core/shell nanostructures offer significantly enhanced freedom in designing novel geometries for nanoconfinement and to achieve exotic optoelectronic properties. For example, a narrow and another wide band gap semiconductor material can be used to form a type one or inverted (type II) core/shell structures [1, 2]. Moreover, the career confinement in core/shell structures can be significantly influenced by controlling the band edge offsets between the core and the shell. Some interesting confinement modes that may ensue following such a material engineering could be (i) electrons/holes in the core and holes/electrons in the * Deepshikha Rathore [email protected] 1
Patanjali Research Institute, Haridwar, Uttarakhand 249405, India
2
Department of Nanoscience and Technology, Calicut University, Thrissur, Kerala 673635, India
3
School of Nanotechnology, Rajiv Gandhi Proudyogiki Vishwavidyalaya, Bhopal, Madhya Pradesh 462033, India
4
Amity School of Applied Sciences, Amity University Rajasthan, Jaipur, Rajasthan 303002, India
5
IMS Unison University, Dehradun, Uttarakhand 248009, India
shell or (ii) one of the carriers confined within the core while the other being delocalized across the whole core/ shell structure. The overall advantage could be in tuning the absorption/emission behaviour over a wide spectral band for application in light emitters or solar cells etc. [3, 4]. To this end, PbSe and CdSe offer some unique advantage. PbSe is known to possess a large Bohr exciton radius, and a smaller electron and hole effective masses. It has a large dielectric constant and a
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