Biological Synthesis of CdS/CdSe Core/Shell Nanoparticles and Its Application in Quantum Dot Sensitized Solar Cells

Abstract

In the present work, we report the use of bacterial cells for the production of CdS/CdSe Core/Shell quantum dots (QDs), a complex nanostructure specially designed to improve their performance as photosensitizer in photovoltaic devices. The method requires the incorporation of L-cysteine, CdCl 2 and Na 2 SeO 3 to Escherichia coli cultures and allows a tight control of QDs properties. The obtained CdS/CdSe QDs were photophysically and structurally characterized. When compared to CdS QDs, the classical shift in the UV-visible spectra of Core/Shell nanostructures was observed in CdS/CdSe QDs. The nanosize, structure, and composition of Core/Shell QDs were confirmed by TEM and EDS analysis. QDs presented a size of approximately 12 nm (CdS) and 17 nm (CdS/CdSe) as determined by dynamic light scattering (DLS), whereas the fourier transform infrared (FTIR) spectra allowed to distinguish the presence of different biomolecules bound to both types of nanoparticles. An increased photostability was observed in CdS/CdSe nanoparticles when compared to CdS QDs. Finally, biosynthesized CdS/CdSe Core/Shell QDs were used as photosensitizers for quantum dots sensitized solar cells (QDSSCs) and their photovoltaic parameters determined. As expected, the efficiency of solar cells sensitized with biological CdS/CdSe QDs increased almost 2.5 times when compared to cells sensitized with CdS QDs. This work is the first report of biological synthesis of CdS/CdSe Core/Shell QDs using bacterial cells and represents a significant contribution to the development of green and low-cost photovoltaic technologies.

Production of cadmium sulfide quantum dots by the lithobiontic Antarctic strain Pedobacter sp. UYP1 and their application as photosensitizer in solar cells

“…This is puzzling considering the fluorescent and structural properties determined for these QDs. Previous works in biosynthesized CdS QDs with similar properties to those described here (size, composition, QY, and emission), reported XRD results indicating the existence of crystalline structures [ 8 , 36 , 37 , 56 ]. This result is most probably a consequence of the amorphous matrix of organic matter that covers the QDs produced by Pedobacter sp.…”

“…Regarding the application of biosynthesized QDs as photosensitizer materials in the construction of solar cells, as far as we can tell, there had been only a few previous works. In Spangler et al [ 57 ], an engineered strain of Stenotrophomonas maltophilia was used to produce PbS NPs, while in the works Órdenes-Aenishanslins et al [ 56 , 58 ], the bacteria employed was an Escherichia coli strain that was able to synthesize CdS QDs. To date, Pedobacter genus has not been used for this purpose.…”

“…Quantum dots sensitized solar cells were constructed as in the protocol described by Órdenes-Aenishanslins et al [ 56 ] with minor modifications. Electrodes with an area of 20 × 20 × 2 mm size were used with fluorine doped tin oxide coated glass (FTO glass) TEC15, with surface resistivity of 13 Ω sq −1 and 82–84.5% of transmittance (Sigma-Aldrich).…”

Bacterial Synthesis of Ternary CdSAg Quantum Dots through Cation Exchange: Tuning the Composition and Properties of Biological Nanoparticles for Bioimaging and Photovoltaic Applications

“…This biosynthetic process is highly versatile and has been recently used for the controlled production of CdS/CdSe Core/Shell QDs. These Cd-based nanomaterials were specifically designed for photovoltaic applications and their use as "bio-sensitizers" in QDs-sensitized solar cells was reported for the first time [22]. Based on this and the inherent advantages of using microorganisms as nanocrystal bio-factories, we believe that the biosynthesis process constitutes a unique opportunity to generate nanoparticles with improved properties, such as ternary QDs, that could contribute to the development of new technologies and applications.…”

Synthesis of CdS/CdSe Core/Shell Heterostructures Using Ultrasonic Assisted Sol–Gel Method

“…As a solution, investigators have found that the heterogeneous, composite semiconductors have superior optical optoelectronic and physical properties as compared to the single material [12]. In recent years, a single semiconductor material coated with another material (known as core/shell nanostructure) has also gained prominence [13][14][15][16][17][18]. The shell materials are coated for controlling the reactivity and stability of the core [19].…”