Quantum dot sensitized solar cell based on TiO2/CdS/CdSe/ZnS heterostructure

• QDSSC fabrication using unidimensional TiO2 nanostructures.
• High surface area for QDs loading.
• Strong absorption in the visible regime for TiO2/CdS/CdSe/ZnS.
• The QDSSC show improved photocurrents.
• High power conversion efficiency of 2.56%.

A cascade structure of TiO2/CdS/CdSe/ZnS quantum dot sensitized solar cell (QDSSC) is achieved to boost the photoconversion efficiency of TiO2/CdSe system by incorporating inner buffer layer of CdS. A sodium dodecyl sulfate (SDS) surfactant mediated TiO2 nanorods assembly is prepared by a simple hydrothermal technique. The formation of CdS, CdSe and ZnS thin film over TiO2 nanorods assembly as a photoanode is carried out by successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) techniques. Thus synthesized electrode materials are characterized by XRD, XPS, field emission scanning electron microscopy (FE-SEM), TEM, High resolution-TEM (HR-TEM), STEM-EDS mapping, Optical and solar cell performances. The results designate that the thin film of CdS and CdSe have efficiently covered exterior surfaces of TiO2 nanorods assembly. The interfacial structure of TiO2/CdS/CdSe is also investigated and the growth interface is verified. A cautious evaluation between CdSe and CdS/CdSe sensitized cells tells that CdS helps to enhance the further growth of CdSe in the cascade electrodes and improves light harvesting. Under AM 1.5G illumination, the photoanodes show an improved power conversion efficiency of 2.56%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 4.80 mA cm−2 which is 18 times higher than that of a bare TiO2 nanorods assembly.

A cascade structure of TiO2/CdS/CdSe/ZnS quantum dot sensitized solar cellis achieved to boost the photoconversion efficiency for TiO2/CdSe system by incorporating inner layer of CdS.Figure optionsDownload as PowerPoint slide