Engineering the energy bandgap of lead cobalt sulfide quantum dots for visible light optoelectronics
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Engineering the energy bandgap of lead cobalt sulfide quantum dots for visible light optoelectronics Ali Badawi1,* 1
Department of Physics, Faculty of Science, Taif University, Taif, Saudi Arabia
Received: 15 April 2020
ABSTRACT
Accepted: 23 August 2020
The energy bandgap of ternary alloyed lead cobalt sulfide quantum dots has been engineered for visible light optoelectronic applications. Ternary Pb0.8Co0.2S QDs were synthesized in situ onto TiO2 electrodes using a sub-sequential chemical bath deposition method up to 7 times. The surface morphology of the prepared alloyed Pb0.8Co0.2S QDs photoanodes was characterized using a transmission electron microscope. The X-ray diffraction technique was used to study the structural properties of the prepared alloyed photoanodes. The optical properties were characterized using a UV–visible–NIR spectrophotometer in the visible region range. The absorption of the prepared photoanodes increases as the no. of deposition times rises up to 7. Besides, the energy bandgap of the alloyed photoanodes is red-shifted from 3.15 eV (393 nm) to 1.68 eV (738 nm). These bandgap red shifts are mainly attributed to the quantum confinement effect. Based on optical properties measurements, the prepared ternary alloyed QDs could be utilized effectively in visible light optoelectronic applications.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Recently, semiconductor nanoparticles have been paying close attention because of their unique characteristics. The novelty of the optical, thermal, mechanical, and electrical properties qualifies them to act the role of the leader in many applications. These applications involve different industrial, medical, and agricultural fields [1–4]. Semiconductors quantum dots (QDs) achieve a high level of significance due to the ability of controlling their properties. For example, the QDs’ optical properties could be tuned for such an application, based on two strategies: adjusting their size and shape or varying their
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https://doi.org/10.1007/s10854-020-04327-1
components’ ratios through alloying. A lot of previous work have been made on tuning the QDs’ optical properties. Mostly, these works are focused on cadmium chalcogenides (S, Te and Se) [1, 5, 6], PbS [7], Ag2 S[2], CdTexS1-x[8], Cd1-xPbxS [9], and Pb1-x ZnxS [10] due to their low cost, availability, and ease of preparation [11]. For example, Khalid et al. [12] tuned the optical and thermal properties of CdS QDs by controlling their size for photovoltaic applications. Zhang et al. [13] showed that Ag2S QDs could be tuned by size control to be used as fluorescent probes with high biocompatibility. On the other hand, many works have taken place to perform the second strategy of adjusting the QDs’ optical properties by
J Mater Sci: Mater Electron
varying the atomic ratios of the QD components. For example, Al-Hosiny et al. [8] prepared CdTexS1-x 1QDs by varying the molar ratios of Te and S for solar cells
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