Multilayered Semiconductor (CdS/CdSe/ZnS)-Sensitized TiO₂ Mesoporous Solar Cells: All Prepared by Successive Ionic Layer Adsorption and Reaction Processes

Abstract

A model semiconductor-sensitizer layer of CdSe with under- or overlayers of CdS or ZnS by pre- or postadsorption was prepared on the surface of mesoporous TiO2 films by a series of successive ionic layer adsorption and reaction (SILAR) processes in solutions containing corresponding cations and anions. The growth of each semiconductor layer was monitored by taking UV−visible absorption spectra and high-resolution transmission electron microscopy (TEM) images. The all SILAR-prepared multicomponent sensitizer consisting of CdS/CdSe/ZnS layers was evaluated in a polysulfide electrolyte solution as a redox mediator in regenerative photoelectrochemical cells. The CdS and ZnS layers with the CdSe layer sandwiched in between were found to significantly enhance photocurrents. The best photovoltaic performance was obtained from the CdS/CdSe/ZnS-sensitizer with the ZnS layer on the top, yielding an overall power conversion efficiency of 3.44% with a mask around the active film and 3.90% with no mask. The effect of the mask on short-circuit current (J sc) and overall efficiency (η) measurements was shown to be increasingly critical in semiconductor-sensitized solar cells as they exhibit high photocurrents. The polysulfide electrolyte, which acted as an effective electron transfer mediator for CdS and/or CdSe sensitizers, was not as effective for PbS-based sensitizers prepared by the same SILAR process.

ZnS/SiO2 Passivation Layer for High-Performance of TiO2/CuInS2 Quantum Dot Sensitized Solar Cells

“…QD loading and well controllable in size and density of the target semiconductor QDs and efficient electron transfer to TiO2 [13,14].…”

Enhanced photovoltaic performance of a quantum dot-sensitized solar cell using a Nb-doped TiO2 electrode

“…Table 1 shows the quantitative results which are in good agreement with the theoretical values. CdS and CdSe quantum dots are widely used as semiconductor sensitizers for QDSSCs because their composite absorption spectrum covers most of the visible light region [27][28][29]. A successive ionic layer adsorption and reaction method offers the possibility to deposit a high density of QDs onto nanocrystalline electrodes with low aggregation.…”

Enhanced performance of solar cells via anchoring CuGaS2 quantum dots

“…The chalcopyrite semiconductor quantum dots (QDs), such as CdS(Se) [13][14][15][16][17][18][19][20], PbS(Se) [21][22][23][24], SnSe 2 [25], InAs [26,27], Sb 2 S 3 [28], were introduced into QDSSCs as light-harvesting sensitizers via various methods. Since photons with lower energy could be absorbed, the chalcopyrite semiconductor QDs are considered as a promising candidate for the high-efficiency solar cells [29].…”