Charge transport in lead sulfide quantum dots/phthalocyanines hybrid nanocomposites |
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Affiliation: | 1. Institute of Materials and Manufacturing, Brunel University London, Uxbridge, Middlesex UB8 3PH, UK;2. School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK;3. United States Air Force Research Laboratory, Space Vehicles Directorate, SE Kirtland AFB, NM 87117, USA |
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Abstract: |  A hybrid composite of non-aggregated lead sulfide (PbS) nanoparticles of average size 5.8 ± 1 nm embedded within a film of an octaalkyl substituted metal-free phthalocyanine (Compound 2) was prepared on interdigitated gold electrodes by mild acidic treatment of newly synthesised octasubstituted lead phthalocyanine analogue (Compound 1) in solid state phase. This nanocomposite film shows an enhancement of in-plane electrical conductivity over that of a film of octaalkyl substituted metal-free phthalocyanine alone by nearly 65%. This observation is consistent with the formation of charge complex compound as indicated by Raman and XPS data. The presence of PbS in the composite was examined on the basis of XRD peak positions which are comparable with those of bulk PbS. A band gap of 2.22 eV was calculated from optical absorption data using Tauc's law, implying quantum confinement. The mono dispersal behaviour of PbS nanoparticles was established from TEM and XRD studies. The hopping conduction mechanism is found to be primarily responsible for charge transport in the hybrid nanocomposite film with the hopping distance larger than PbS diameter. |
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Keywords: | Bohr radius Quantum confinement Photophysical quenching Percolation limit Hopping conduction Memristors |
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