ZnO Nanoparticles−CdS Quantum Dots/N3 Dye Molecules: Dual Photosensitization

Abstract

We developed dual photosensitization, in which CdS quantum dots serve as a sandwich layer between the ZnO nanoparticles (NPs) and N3 dye molecules, alleviating the serious issues of CdS photocorrosion and the Zn 2+ /N3 dye complex formation leading to insulating surface aggregation. The improvement in the solarto-electrical conversion efficiency from 0.11 and 0.85 to 3.04% when compared to ZnO/N3 and ZnO-CdS, respectively, is attributed to the effective coupling between the ZnO NPs/N3 dye molecules in the presence of CdS QDs, which in turn enhances the rate of electron injection due to the faster electron injection and transfer rate. Strong ZnO NPs-CdS QDs linking is explored systematically using UV-vis spectroscopy and is interpreted with a charge transfer resistance obtained from impedance spectroscopy studies.

Photoinduced Charge Transfer Properties of ZnWO4/CdS Composite and its Photocatalytic Activities under visible Light

“…(IV) At time longer than 10 -6 s (P2), the time of TPV maximum of ZnWO 4 /CdS composite in comparison to that of the bare CdS is strongly retarded, which is typical for diffusion photovoltage. These result indicates that ZnWO 4 grown on the surface of CdS can restrict a part of photoinduced hole and inhibit the photocorrosion of CdS [16]。The larger retardation time is, the lower recombination rate of electron-hole pairs will be. This means that photo-induced charges will have more time to participate in the photocatalytic reaction before recombination.…”

Uniform deposition of coupled CdS and CdSe quantum dots on ZnO nanorod arrays as electrodes for photoelectrochemical solar water splitting

“…The multi-QD sensitized ZnO or TiO 2 photoelectrodes in PV or PEC devices consist of a film of randomly packed nanoparticles [13,15,16] or orientated arrays [17e19]. Even a type-I band structure between the relative band positions of bulk CdS and CdSe, superior photogenerated carrier collection between CdS and CdSe QDs during PEC operation had been demonstrated due to Fermi level alignment [20].…”

Core-shell ZnO@CuInS2 hexagonal nanopyramids with improved photo-conversion efficiency

“…Semiconductors such as CdS [10,11], PbS [12,13], Bi 2 S 3 [14], CdSe [15], and InP [16] which absorb light in the visible region, can serve as sensitizers as they are able to transfer photogenerated electrons to large band gap semiconductors such as TiO 2 or SnO 2 or ZnO. Over the past few years, the assembling of quantum dots with higher absorption coefficient on the polycrystalline surfaces of the ZnO nanostructures has been investigated as an alternative of conventional dye-sensitized solar cell [17,18]. Guerguerian et al reported improved conversion efficiency of solar cells based on ZnO@CdS core-shell nanocrystals [19].…”