skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Comparative behavior of CdS and CdSe quantum dots in poly(3-hexylthiophene) based nanocomposites

Abstract

CdS and CdSe nanoparticles have been prepared using conducting poly(3-hexylthiophene) (P3HT) matrix with an objective to understand the effect of nanoparticles on the polymer matrix using electrochemical and spectroscopic techniques. The spectroscopic results reveal that the electronic structure of polymer is strongly influenced by the characteristics of embedded semiconducting nanoparticles. SEM and TEM images show the ordered morphology of the CdS and CdSe nanoparticles in presence of the polymer matrix. Cyclic voltammetry performed both in the presence and absence of light enables us to understand the redox changes in P3HT due to CdS and CdSe quantum dots such as the generation of free radical in the excited state and their electrochemical band gaps.

Authors:
 [1];  [2];  [2];  [3]
  1. Swiss Federal Institute of Technology, ETH-Hoenngerberg, 8092-Zurich (Switzerland). E-mail: sonar@mat.ethz.ch
  2. Physical and Materials Chemistry Division, National Chemical Laboratory, Pune-411008 (India)
  3. Physical and Materials Chemistry Division, National Chemical Laboratory, Pune-411008 (India). E-mail: viji@ems.ncl.res.in
Publication Date:
OSTI Identifier:
20891609
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 41; Journal Issue: 1; Other Information: DOI: 10.1016/j.materresbull.2005.07.032; PII: S0025-5408(05)00273-4; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CADMIUM SELENIDES; CADMIUM SULFIDES; COMPOSITE MATERIALS; ELECTROCHEMISTRY; ELECTRONIC STRUCTURE; EXCITED STATES; IMAGES; MORPHOLOGY; POLYMERS; QUANTUM DOTS; SCANNING ELECTRON MICROSCOPY; VOLTAMETRY

Citation Formats

Sonar, Prashant, Sreenivasan, K.P., Madddanimath, Trupti, and Vijayamohanan, K. Comparative behavior of CdS and CdSe quantum dots in poly(3-hexylthiophene) based nanocomposites. United States: N. p., 2006. Web. doi:10.1016/j.materresbull.2005.07.032.
Sonar, Prashant, Sreenivasan, K.P., Madddanimath, Trupti, & Vijayamohanan, K. Comparative behavior of CdS and CdSe quantum dots in poly(3-hexylthiophene) based nanocomposites. United States. doi:10.1016/j.materresbull.2005.07.032.
Sonar, Prashant, Sreenivasan, K.P., Madddanimath, Trupti, and Vijayamohanan, K. Thu . "Comparative behavior of CdS and CdSe quantum dots in poly(3-hexylthiophene) based nanocomposites". United States. doi:10.1016/j.materresbull.2005.07.032.
@article{osti_20891609,
title = {Comparative behavior of CdS and CdSe quantum dots in poly(3-hexylthiophene) based nanocomposites},
author = {Sonar, Prashant and Sreenivasan, K.P. and Madddanimath, Trupti and Vijayamohanan, K.},
abstractNote = {CdS and CdSe nanoparticles have been prepared using conducting poly(3-hexylthiophene) (P3HT) matrix with an objective to understand the effect of nanoparticles on the polymer matrix using electrochemical and spectroscopic techniques. The spectroscopic results reveal that the electronic structure of polymer is strongly influenced by the characteristics of embedded semiconducting nanoparticles. SEM and TEM images show the ordered morphology of the CdS and CdSe nanoparticles in presence of the polymer matrix. Cyclic voltammetry performed both in the presence and absence of light enables us to understand the redox changes in P3HT due to CdS and CdSe quantum dots such as the generation of free radical in the excited state and their electrochemical band gaps.},
doi = {10.1016/j.materresbull.2005.07.032},
journal = {Materials Research Bulletin},
number = 1,
volume = 41,
place = {United States},
year = {Thu Jan 05 00:00:00 EST 2006},
month = {Thu Jan 05 00:00:00 EST 2006}
}
  • A comparative study on electrical performance, optical properties, and surface morphology of poly(3-hexylthiophene) (P3HT) and P3HT-nanofibers based “normally on” type p-channel field effect transistors (FETs), fabricated by two different coating techniques has been reported here. Nanofibers are prepared in the laboratory with the approach of self-assembly of P3HT molecules into nanofibers in an appropriate solvent. P3HT (0.3 wt. %) and P3HT-nanofibers (∼0.25 wt. %) are used as semiconductor transport materials for deposition over FETs channel through spin coating as well as through our recently developed floating film transfer method (FTM). FETs fabricated using FTM show superior performance compared to spin coated devices;more » however, the mobility of FTM films based FETs is comparable to the mobility of spin coated one. The devices based on P3HT-nanofibers (using both the techniques) show much better performance in comparison to P3HT FETs. The best performance among all the fabricated organic field effect transistors are observed for FTM coated P3HT-nanofibers FETs. This improved performance of nanofiber-FETs is due to ordering of fibers and also due to the fact that fibers offer excellent charge transport facility because of point to point transmission. The optical properties and structural morphologies (P3HT and P3HT-nanofibers) are studied using UV-visible absorption spectrophotometer and atomic force microscopy , respectively. Coating techniques and effect of fiber formation for organic conductors give information for fabrication of organic devices with improved performance.« less
  • We show that graphene quantum dots (GQD) embedded in a semiconducting poly(3-hexylthiophene) polymeric matrix act as charge trapping nanomaterials. In plane current-voltage (I-V) measurements of thin films realized from this nanocomposite deposited on gold interdigitated electrodes revealed that the GQD enhanced dramatically the hole transport. I-V characteristics exhibited a strong nonlinear behavior and a pinched hysteresis loop, a signature of a memristive response. The transport properties of this nanocomposite were explained in terms of a trap controlled space charge limited current mechanism.
  • Photo-induced electron transfer between poly-(3-hexylthiophene) (P3HT) and small (2.4 nm) PbS quantum dots (QDs), capped by different ligands, was studied by picosecond and femtosecond time-resolved fluorescence and by photo-induced absorption (PIA) measurements. In line with previous experiments, we observed that the efficiency of the quenching of P3HT by PbS QDs increased upon decreasing the average thickness of the ligand shell. This trend was also observed in the PIA spectra and in prior work on the performance of photovoltaic devices where the active layer was a blend of P3HT with PbS QDs capped by different ligands. Combining the pico- and femtosecond fluorescencemore » decays showed that the quenching in blend films of P3HT and PbS QDs treated with 1,4-benzenedithiol occurred over a broad time scale ranging from tens of femtoseconds to hundreds of picoseconds. This complex kinetics was attributed to exciton hopping followed by electron transfer to the conduction band of the QDs. We also compared the wavelength dependence of the internal quantum efficiency (IQE) in the hybrid photovoltaic devices to those devices where the photoactive layer consists of PbS QDs only. Although excitation in the first excitonic transition of the PbS QDs yielded a similar IQE in both devices, the IQE of the hybrid devices tripled at wavelengths where also P3HT started to absorb. This suggests that upon excitation of P3HT in the latter devices, charge generation occurs by photo-induced electron transfer from P3HT to the QDs rather than by energy transfer to the QDs followed by exciton dissociation in the QDs.« less
  • The synthesis of well-defined, end-functional poly(3-hexylthiophene)s (P3HTs) by in situ quenching of the Grignard metathesis (GRIM) polymerization is complicated by the extreme tendency to favor difunctional products in all but a few cases. A facile one-pot method for preparing 2-pyridyl and 3-pyridyl P3HTs with high abundance of monofunctional products is established via an examination of the kinetics of the end-functionalization quenching reaction with lithium chloride complexes of 2- and 3-pyridyl Grignard reagents. Density functional theory calculations guide the selection of pyridine as the end group, which provides the capacity to ligate cadmium selenide (CdSe) nanocrystals and arrests aggregation upon thermalmore » annealing when dispersed in a P3HT matrix. The relative abundances of various end-functional products, as ascertained by high-resolution matrix assisted laser desorption ionization time-of-flight mass spectrometry, can be altered through the use of 1-pentene as an additive: GRIM polymerizations quenched with 3-pyridyl and 2-pyridyl Grignard reagents show 5% and 18% abundances of difunctional, pyridyl-capped P3HTs, respectively, when 1-pentene is present at 1000:1 relative to the nickel catalyst. This represents a significant improvement compared to quenching with aryl Grignard reagents, where difunctional products predominate. Furthermore, the ability to manipulate end group compositions coupled with the propensity of pyridyl-functionalized P3HTs to ligate semiconductor quantum dots (SQDs) opens new possibilities for tuning the morphology of conjugated polymer/SQD blends.« less
  • Embedding of quantum dots into porous oxide matrixes is a perspective technique for photosensitization of a structure. We show that the sensitization efficiency may be increased by the use of core-shell quantum dots. It is demonstrated that the photoresponse amplitude in a SnO{sub 2} porous matrix with CdSe/CdS quantum dots depends non-monotonously on the number of atomic layers in a shell. The best results are obtained for SnO{sub 2} matrixes coupled with the quantum dots with three atomic layers of a shell. Mechanisms responsible for the structure sensitization are discussed.