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Title: Electronic grade and flexible semiconductor film employing oriented attachment of colloidal ligand-free PbS and PbSe nanocrystals at room temperature
Authors: Shanker, G. Shiva
Swarnkar, Abhishek
Chatterjee, Arindom
Chakraborty, S.
Phukan, Manabjyoti
Parveen, Naziya
Biswas, Kanishka
Nag, Angshuman
Keywords: Chemistry
Nanoscience & Nanotechnology
Materials Science
Applied Physics
Performance Bulk Thermoelectrics
Quantum Dots
Zno Nanocrystals
Surface Ligands
Issue Date: 2015
Publisher: Royal Society of Chemistry
Citation: Nanoscale
Shanker, G. S.; Swarnkar, A.; Chatterjee, A.; Chakraborty, S.; Phukan, M.; Parveen, N.; Biswas, K.; Nag, A., Electronic grade and flexible semiconductor film employing oriented attachment of colloidal ligand-free PbS and PbSe nanocrystals at room temperature. Nanoscale 2015, 7 (20), 9204-9214.
Abstract: Electronic grade semiconductor films have been obtained via the sintering of solution processed PbS and PbSe nanocrystals at room temperature. Prior attempts to achieve similar films required the sintering of nanocrystals at higher temperatures (> 350 degrees C), which inhibits the processing of such films on a flexible polymer substrate, and it is also expensive. We reduced the sintering temperature by employing two important strategies: (i) use of ligand-free nanocrystals and (ii) oriented attachment of nanocrystals. Colloidal ligand-free PbS and PbSe nanocrystals were synthesized at 70 degrees C with high yield (similar to 70%). However, these nanocrystals start to agglomerate with time in formamide, and upon the removal of the solvation energy, nanocrystals undergo oriented attachment, forming larger elongated crystals. PbS and PbSe nanocrystal films made on both glass and flexible substrates at room temperature exhibit Ohmic behavior with optimum DC conductivities of 0.03 S m(-1) and 0.08 S m(-1), respectively. Mild annealing of the films at 150 degrees C increases the conductivity values to 1.1 S m(-1) and 137 S m(-1) for PbS and PbSe nanocrystal films, respectively. AC impedance was measured to distinguish the contributions from grain and grain boundaries to the charge transport mechanism. Charge transport properties remain similar after the repeated bending of the film on a flexible polymer substrate. Reasonably high thermoelectric Seebeck coefficients of 600 mu V K-1 and 335 mu V K-1 for PbS and PbSe nanocrystal pellets, respectively, were obtained at room temperature.
Description: Restricted access
ISSN: 2040-3364
Appears in Collections:Research Papers (Kaniska Biswas)

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