Structural, optical and electrical properties of PbS and PbSe quantum dot thin films

El-Menyawy, E.M.; Mahmoud, G. M.; Ibrahim, Ruhani; Terra, F. S.; El-Zahed, H.; Zawawi, I. K. El

doi:10.1007/s10854-016-5080-6

Cited by 16 publications

(10 citation statements)

References 39 publications

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“…While figure S5 shows the schematic representation of the experimental set up used to measure the electrical properties. Sample GO/PbS shows the greatest resistivity value among the NHM thin films, this is attributed to the low charge transport properties in GO, due to the presence of the O-rich functional groups on its structure, as previously discussed; also due to the high resistivities normally displayed by only-PbS QDs thin films [54], as it was verified in this study. Even though, the resistivity of the GO/PbS sample decreased compared to the resistivity value of GO and PbS thin films samples.…”

Section: Electronic Properties and Photoresponsesupporting

confidence: 83%

“…However, it is proposed that the main factor related to the increment in the photogenerated current, is an improved CC transfer between the PbS QDs and the rGO structures forming the NHM. It has been reported that the reduction process in rGO 'lowers' its WF value [54]. The final value depends on the reduction degree.…”

Section: Electronic Properties and Photoresponsementioning

confidence: 99%

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Solution processed nanostructured hybrid materials based on PbS quantum dots and reduced graphene oxide with tunable optoelectronic properties

Lara-Canche¹,

García-Gutiérrez²,

Gómez³

et al. 2020

Nanotechnology

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Nanostructured hybrid materials (NHMs) are promising candidates to improve the performance of several materials in different applications. In the case of optoelectronic technologies, the ability to tune the optical absorption of such NHMs is an appealing feature. Along with the capacity to transform the absorbed light into charge carriers (CC), and their consequently efficient transport to the different electrodes. In this regard, NHM based on graphene-like structures and semiconductor QDs are appealing candidates, assuming the NHMs retain the light absorption and CC photogeneration properties of semiconductor QDs, and the excellent CC transport properties displayed by graphene-like materials. In the current work a solution-processed NHM using PbS quantum dots (QDs) and graphene oxide (GO) was fabricated in a layer-by-layer configuration by dip-coating. Afterwards, these NHMs were reduced by thermal or chemical methods. Reduction process had a direct impact on the final optoelectronic properties displayed by the NHMs. All reduced samples displayed a decrement in their resistivity, particularly the sample chemically reduced, displaying a 107 fold decrease; mainly attributed to N-doping in the reduced graphene oxide (rGO). The optical absorption coefficients also showed a dependence on the rGO’s reduction degree, with reduced samples displaying higher values, and sample thermally reduced at 300 °C showing the highest absorption coefficient, due to the combined absorption of unaltered PbS QDs and the appearance of sp2 regions within rGO. The photogenerated current increased in most reduced samples, displaying the highest photocurrent the sample reduced at 400 °C, presenting a 2500-fold increment compared to the NHM before reduction, attributed to an enhanced CC transfer from PbS QDs to rGO, as a consequence of an improved band alignment between them. These results show clear evidence on how the optoelectronic properties of NHMs based on semiconductor nanoparticles and rGO, can be tuned based on their configuration and the reduction process parameters.

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Section: Electronic Properties and Photoresponsesupporting

confidence: 83%

Section: Electronic Properties and Photoresponsementioning

confidence: 99%

Solution processed nanostructured hybrid materials based on PbS quantum dots and reduced graphene oxide with tunable optoelectronic properties

Lara-Canche¹,

García-Gutiérrez²,

Gómez³

et al. 2020

Nanotechnology

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“…It is believed that the fundamental absorption edge is one of the most significant characteristics of the absorption spectra of crystalline and non-crystalline (or amorphous) materials [26]. The optical absorption coefficient (α) as a function of the wavelength (λ) of the pure MC and MC nanocomposite films can be evaluated using the following relation [27]:α=1dln[false(1−Rfalse)22T+false(1−Rfalse)44T2+R2] where d is the thickness of the films. The optical absorption coefficient as a function of photon energy was determined for the pure and doped MC samples, as shown in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Polymer Nanocomposites Based on [Methyl Cellulose](1−x):(CuS)x (0.02 M ≤ x ≤ 0.08 M) with Desired Optical Band Gaps

2017

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Abstract:In this paper, the sample preparation of polymer nanocomposites based on methyl cellulose (MC) with small optical bandgaps has been discussed. Copper monosulfide (CuS) nanoparticles have been synthesized from the sodium sulphide (Na 2 S) and copper chloride (CuCl 2 ) salts. Distinguishable localized surface resonance plasmon (LSRP) absorption peaks for CuS nanoparticles within the 680-1090 nm scanned wavelength range were observed for the samples. An absorption edge (E d ) was found to be widely shifted to a lower photon energy region. A linear relationship between the refractive index of the samples and the CuS fraction was utilized to describe the distribution of the particle. The optical bandgap of MC was reduced from 6.2 to 2.3 eV upon the incorporation of 0.08 M of CuS nanoparticles. The optical dielectric loss, as an alternative method, was used successfully to estimate the optical bandgap. Moreover, the electronic transition type was identified by using Tauc's extrapolation method. The plots of the optical dielectric constant and energy bandgap as a function of the CuS concentration were utilized to examine the validity of the Penn model. For the nanocomposite samples, the Urbach energy was found to be increased, which can be evidence for a large possible number of bands-to-tail and tail-to-tail transitions. However, from the X-ray diffraction (XRD) analysis, it was also found that the synthesized CuS nanoparticles disrupted the crystallinity phase of the MC polymer. Finally, fourier transform infrared (FTIR) spectroscopy for the samples was also performed. Significant decreases of transmittance intensity as well as band shifting in the FTIR spectra were observed for the doped samples.

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“…For the proper characterization of associated effects, we compare extinction spectra of the films that were consequently annealed in vacuum for 2 h at temperatures, T ann , in the range from 160 to 300 °C. Although we measured the extinction spectra, due to the weak reflectance of small PbS nanoparticles even at high densities, 49 we ascribe all observed spectral features solely to the absorption (thus, we denote measured data as absorption, α, spectra below). Obtained spectra for both samples after each annealing step are given in Figure 5.…”

Section: Resultsmentioning

confidence: 99%

Effect of Thermal Annealing on Structure and Optical Properties of Poly(p-xylylene)–PbS Thin Films

et al. 2019

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In this study, wide-angle X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy were employed to address the crystalline structure and morphology of poly(p-xylylene)−PbS nanocomposite thin films prepared by vapor deposition polymerization as well as their evolution upon thermal annealing. It was found that as-synthesized samples with different PbS contents demonstrate similar diffraction patterns that cannot be fully ascribed to a decrease in crystallite size, indicating distorted crystal structure of PbS nanoparticles compared to the bulk PbS. X-ray absorption spectroscopy reveals wide distribution of Pb−S bond lengths with a minimum value of 2.67 Å, which can be attributed to the presence of molecular (PbS) n clusters in the studied films. It was shown that thermal annealing can be used to control the size of PbS nanoparticles and, as a consequence, optical properties of the composite films. The UV−vis absorption spectra demonstrate pronounced red shift of the absorption edge correlated with the growth of PbS nanoparticles upon annealing. Comprehensive analysis of several theoretical models describing the effect of nanoparticles size on optical band gap of the composite material has been performed and compared with the experimental data.

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Structural, optical and electrical properties of PbS and PbSe quantum dot thin films

Cited by 16 publications

References 39 publications

Solution processed nanostructured hybrid materials based on PbS quantum dots and reduced graphene oxide with tunable optoelectronic properties

Solution processed nanostructured hybrid materials based on PbS quantum dots and reduced graphene oxide with tunable optoelectronic properties

Synthesis of Polymer Nanocomposites Based on [Methyl Cellulose](1−x):(CuS)x (0.02 M ≤ x ≤ 0.08 M) with Desired Optical Band Gaps

Effect of Thermal Annealing on Structure and Optical Properties of Poly(p-xylylene)–PbS Thin Films

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