CdS Q-Dot-Impregnated TiO₂-B Nanowire-Based Photoanodes for Efficient Photovoltaic Conversion in ‘Q-Dot Co-sensitized DSSC’

Abstract

Cadmium sulfide (CdS) as a narrow-band-gap semiconductor has been coupled in 0–15 wt % to hydrothermally grown titanium dioxide bronze-phase (TiO2-B) nanowires (TNWs), reducing the optical band gap from 2.96 to 2.71 eV. In CdS Q-dot-impregnated TNW/CdS composite nanowires, absorption of light extends toward the visible range of the solar spectrum and effective light-harvesting improves via increased specific surface area; furthermore, the properly aligned band edges between CdS and TiO2-B ascertain efficient separation of the photogenerated charge carriers. Overall, an optimum photoanode material characteristic has been demonstrated in TNW/CdS-10 nanocomposite that achieves a typical photovoltaic (PV) conversion efficiency, η ∼ 1.63%, in Q-dot-sensitized solar cells (QDSSCs), compared to the η ∼ 0.86% of the simple electrochemical cell with a pristine TNW photoanode. N3 dye sensitization of the pristine TNW photoanode leads to a conversion efficiency of η ∼ 3.88% in dye-sensitized solar cells (DSSCs). When the CdS Q-dot-sensitized TNW/CdS-10 photoanode is further co-sensitized by the N3 dye, an enhanced PV conversion efficiency of η ∼ 8.04% is attained in the “Q-dot co-sensitized DSSC” device by virtue of the optimum light absorption facilitated by the maximum dye-loading capacity retained by the widest available surface area on the composite photoanode, contributing to a superior incident-photon-to-current conversion efficiency (IPCE) of ∼ 69.60% at 520 nm. Interfacial electron injection and the recombination dynamics of the cells studied using impedance spectroscopy demonstrate that the DSSC performance increases due to minimization of the electron–hole recombination rate and the increase of the conduction of charge carriers via reduced charge-transfer resistance of the photoanode­(Q-dots/dye)/electrolyte interface at an optimum 10 wt % CdS loading. Sequential sensitization of TiO2-B nanowire photoanodes via CdS Q-dot impregnation and further by N3 dye molecule adsorption improves light-harvesting, facilitates efficient photocarrier generation, and prevents interfacial charge recombination, and their cumulative electron injection results in a better photovoltaic performance via novel “CdS Q-dots and N3 dye co-sensitization of TiO2-B NWs” in Q-dot co-sensitized DSSCs.

Optimized photoelectric conversion properties of PbS x Se1−x -QD/MoS2-NT 0D–1D mixed-dimensional van der Waals heterostructures

“…To appraise the photoelectric conversion properties of PbS x Se 1−x -QDs/MoS 2 -NT 0D-1D MvdW heterostructures, we compare this result with other 0D-1D heterostructures (figure 5(d)). Apparently, the reported PCEs of 0D-1D heterostructures are in the range of 0.29%-4.78% for the past few years, which is much lower than that the present work [10,16,17,19,[52][53][54][55]. This is mainly due to the outstanding light absorptance and extremely fast charge transfer in PbS x Se 1−x -QDs/MoS 2 -NT 0D-1D MvdW heterostructures.…”

Two-Step Visible Light Photocatalytic Dye Degradation Phenomena in Ag2O-Impregnated ZnO Nanorods via Growth of Metallic Ag and Formation of ZnO/Ag0/Ag2O Heterojunction Structures

“…To study the changes in the band gap energy of ZnO/Ag 2 O nanocomposites at different Ag 2 O contents on the pristine mesoporous ZnO nanorods, the corresponding UV–vis spectra were appraised by measuring the diffuse reflectance spectra (DRS), as shown in Figure a. The optical absorption spectra were obtained using the diffuse reflectance data in the Kubelka–Munk function where R is the reflectance and F­(R) remains proportional to the absorbance coefficient (α) when the scattering coefficient maintains a constant magnitude with wavelength.…”

“…30 The Ag peaks shift to a lower binding energy (BE), by which electrons To study the changes in the band gap energy of ZnO/Ag 2 O nanocomposites at different Ag 2 O contents on the pristine mesoporous ZnO nanorods, the corresponding UV−vis spectra were appraised by measuring the diffuse reflectance spectra (DRS), as shown in Figure 8a. The optical absorption spectra were obtained using the diffuse reflectance data in the Kubelka−Munk function 52…”

Review on the Revolution of Polymer Electrolytes for Dye-Sensitized Solar Cells

“…Presently, there are rapid developments in new emerging PV technologies, namely, as perovskite solar cells (PSCs). These lead-based thin-film devices have promptly and greatly outperformed the record PV efficiencies by two times larger and seen as promising to compete with first-generation solar cells in the near future, surpassing the role and prospect of DSSCs for larger solar power plant applications. − However, currently there are still limited choices of perovskite materials and their stability and toxicity remain extremely serious issues. Thus, DSSCs must be considered still practicable and can be developed over the coming years, providing an opportunity to build solar cells with transparency in different color options and a wide range of shapes. ,− But, compared to the silicon p–n junction solar cells, the major challenge faced by DSSCs to be commercialized is low efficiency, which is only 14% compared to the maximum estimated theoretical efficiency of about 32%, along with long-term stability. , In order to be commercialized, DSSCs should have high efficiency and long-term durability.…”