PbS Quantum Dot-sensitized Solar Cells Research Articles

Impact of number of sensitizer SILAR cycles on the performance of ZnO based PbS quantum dot-sensitized solar cells

Impact of number of sensitizer SILAR cycles on the performance of ZnO based PbS quantum dot-sensitized solar cells

Surface Plasmon Resonance Enhancement of PbS Quantum Dot-Sensitized Solar Cells

Lead sulfide (PbS)-sensitized quantum dot solar cells (QDSC) were fabricated using TiO2 and TiO2–Au plasmonic nanocomposite films by successive ionic layer adsorption and reaction (SILAR) method. The average size of gold nanoparticles (GNPs) used for fabricating nanocomposite films was ~ 15 nm. Thin plasmonic QDSC, with a film thickness of 10 µm, showed an increase of ~ 11% in photocurrent and ~ 6% in overall energy conversion efficiency compared to the device without GNPs. The improved performance of QDSCs is attributed to the increased absorption due to the plasmonic near-field effects of the incorporated GNPs. High-efficiency PbS/CdS-co-sensitized thick cells with 16 µm bilayer TiO2 also showed improvement in photocurrent and efficiency. The results show that the plasmonic-enhanced absorption can be used to augment efficiency of QDSC devices in much the same fashion as that of dye-sensitized solar cells.

Enhanced efficiency of PbS quantum dot-sensitized solar cells using plasmonic photoanode

In this report, an effort has been made to develop an efficient PbS quantum dot-sensitized photoanode by simple successive ionic layer adsorption and reduction technique to enhance the overall photovoltaic performance of PbS quantum dot-sensitized solar cells. Three strategies have been adopted for the improvement of the photovoltaic performance of PbS quantum dot-sensitized solar cells, i.e., (i) by incorporation of TiO2-Au nanocomposites, where Au nanoparticles of different sizes are embedded into a TiO2 matrix, and (ii) variation of temperature at which quantum dots are deposited (iii) by postdeposition annealing of QD-sensitized photoanode in Ar atmosphere. We have used electrophoretic deposition technique to develop the nanocomposite-doped photoanode. High-resolution transmission electron microscopy confirms that the Au particles dispersed in the TiO2 matrix vary from 2 to 50 nm and PbS quantum dot size ranges 3.5–6 nm. The optical absorption of PbS quantum dot-sensitized TiO2-Au-incorporated photoanode is substantially enhanced as confirmed from the UV-visible absorption spectra measurements. The current-voltage characteristics of all the plasmonic quantum dot-sensitized solar cells under illumination (100 mW/cm2, AM 1.5) show significant improvement in power conversion efficiency using the abovementioned strategies. The maximum power conversion efficiency observed in PbS quantum dot-based quantum dot-sensitized solar cells is 7.0%. Electroimpedance spectroscopy has been utilized to understand the recombination kinetics in these solar cells.

A novel, PbS:Hg quantum dot-sensitized, highly efficient solar cell structure with triple layered TiO2 photoanode

Hg-doped PbS quantum dot-sensitized solar cells (QDSSCs) were fabricated using successive ionic layer adsorption and reaction method with TiO2 single layer, double layer and triple layer photoanode nanostructures. The triple layer TiO2 photoanode was fabricated by using a TiO2 nanofibre (NF) layer sandwiched between two TiO2 nanoparticle (NP) layers in order to enhance light harvesting through effective light scattering process. The performance of this photoanode has been further enhanced by the surface charge control process and mild annealing treatment. TiO2 triple layer nanostructure based QDSSC showed a significantly higher energy conversion efficiency of 4.72% under the simulated light of 100 mW cm−2 with AM 1.5 filter. The efficiency of the best solar cell made with a single layer of TiO2 nanoparticles under the same conditions was 2.94%. The enhanced solar cell efficiency has been attributed to improved light harvesting by multiple light scattering in the tri-layer TiO2 photoanode structure combined with efficient electron transport with less recombination as evidenced from electrochemical impedance spectroscopic measurements.

High-Performance Solid-State PbS Quantum Dot-Sensitized Solar Cells Prepared by Introduction of Hybrid Perovskite Interlayer.

High-performance solid-state PbS quantum dot-sensitized solar cells (QD-SSCs) with stable 9.2% power conversion efficiency at 1 Sun condition are demonstrated by introduction of hybrid perovskite interlayer. The PbS QDs formed on mesoscopic TiO2 (mp-TiO2) by spin-assisted successive precipitation and anionic exchange reaction method do not exhibit PbSO4 but have PbSO3 oxidation species. By introducing perovskite interlayer in between mp-TiO2/PbS QDs and poly-3-hexylthiophene, the PbSO3 oxidation species are fully removed in the PbS QDs and thereby the efficiency of PbS QD-SSCs is enhanced over 90% compared to the pristine PbS QD-SSCs.

Long wavelength optical absorption and photovoltaic performance enhancement on CuInS2 and PbS quantum dot co-sensitized solar cells

CuInS2 and PbS quantum dots (QDs) are prepared by successive ionic layer adsorption and reaction (SILAR) process for photo-anode of quantum dot sensitized solar cells (QDSSCs). And the optical properties and photovoltaic performance of CuInS2 and PbS QDSSCs with different structure are investigated. The absorption intensity is obviously enhanced and absorption edge is expanded to the near-infrared region for the TiO2/PbS/CuInS2 QDSSCs. The TiO2/3PbS/4CuInS2 QDSSCs have the great photovoltaic conversion efficiency of 2.93%, which is attributed to the better photocurrent response at long wavelength region and band energy level matching of CuInS2 and PbS QDs to improve charge generation and transfer performance.

A novel anion-exchange strategy for constructing high performance PbS quantum dot-sensitized solar cells

Abstract Near-infrared responsive PbS quantum dots (QDs) have received particular attention serving as promising candidates for next generation photovoltaics. This work explores a novel anion-exchange strategy to produce high quality in-situ grown PbS QDs on mesoporous TiO2 films. Such an anion-exchange reaction occurs between PbSO3 and S2− in aqueous solution at low temperature under ambient conditions. A solar cell based on such anion-exchanged PbS QDs yields an impressive power conversion efficiency of 3.06% without resorting to any doping or co-sensitization, achieving around 200% performance improvement with respect to that of a conventional successive ionic layer adsorption and reaction (SILAR) processed device. Based on detailed microscopic, optical and electrochemical characterizations, much enhanced photovoltaic performance is attributed to improved electron injection and collection efficiencies. Up-shifted conduction band level of reasonable small-sized PbS QDs processed by anion-exchange gives rise to desired electron injection from PbS to TiO2, while simultaneous deposition of ZnS passivation layer along with the formation of anion-exchanged PbS QDs allows the minimization of interface states for reduced charge recombination. This work offers an alternative promising approach for constructing high performance PbS QD-sensitized solar cells.

Bifacial illuminated PbS quantum dot-sensitized solar cells with translucent CuS counter electrodes

This paper reports the optimization of the TiO2 photoanode and the fabrication of bifacial illuminated PbS quantum dot-sensitized solar cells (QDSSCs) with translucent CuS counter electrodes. TiO2 photoanode is prepared by introducing a compact TiO2 layer between FTO substrate and TiO2 film with titanium diisopropoxide bis(acetylacetonate) in 1-butanol and post-treatment with TiCl4 aqueous solution; then, PbS quantum dots (QDs) are deposited on the surface of TiO2 film by successive ionic layer adsorption and reaction method; also, by means of control of the TiO2 surface charge, QD density of TiO2 film is improved by adding triethanolamine into the cationic precursor solution. Using this optimized TiO2 photoanode and a translucent CuS counter electrode, a bifacial illuminated PbS QDSSC is fabricated. The preparation conditions are optimized and the surface morphology and electrochemical properties of TiO2 photoanodes are characterized. The bifacial illuminated PbS QDSSC achieves a power conversion efficiency of 2.16 %, which is increased by 48.97 % compared with the single illuminated QDSSC.

Design and development of highly efficient PbS quantum dot-sensitized solar cells working in an aqueous polysulfide electrolyte

PbS quantum dot-sensitized solar cells (QDSCs) with a photovoltaic conversion efficiency (η) of 5.73% have been fabricated by applying Au/CuS/FTO as a counter electrode (CE), post-annealing the deposited PbS QDs, and introducing the bilayered TiO2 nanostructure as a photoanode.

Efficiency enhancement of solid-state PbS quantum dot-sensitized solar cells with Al2O3 barrier layer

Atomic layer deposition (ALD) was used to grow both PbS quantum dots and Al2O3 barrier layers in a solid-state quantum dot-sensitized solar cell (QDSSC). Barrier layers grown prior to quantum dots resulted in a near-doubling of device efficiency (0.30% to 0.57%) whereas barrier layers grown after quantum dots did not improve efficiency, indicating the importance of quantum dots in recombination processes.

Effect of ZnS coatings on the enhancement of the photovoltaic properties of PbS quantum dot-sensitized solar cells

We have studied the effect of ZnS coatings on the photovoltaic properties of PbS quantum dot-sensitized solar cells (QDSSCs). PbS QDs are suitable materials for QDSSCs because of their wide light absorption range; however, their high photochemical reactivity is a problem that needs to be overcome for solar cell applications. In this paper, a ZnS passivation layer was applied to PbS QDs adsorbed onto electrodes using a successive ionic layer adsorption and reaction (SILAR) method for different numbers of cycles in both aqueous and methanol solutions. It was demonstrated that, as a consequence of the low viscosity of methanol, the performance of the PbS QDSSCs was greatly enhanced when a methanol, rather than aqueous, solution was used in the SILAR method. The optical absorption properties of PbS QDs adsorbed on TiO2 electrodes with or without ZnS surface passivation were studied. An increase in size of the PbS QDs after coating with ZnS was confirmed by a red shift in the optical absorption spectra measured using photoacoustic spectroscopy. The photovoltaic properties of a sandwich structure of PbS QDSSCs were studied under “one sun” illumination using a polysulfide (S/S2−) redox system as the electrolyte and Cu2S on brass as the counter electrode. The short-circuit current density dramatically increased from 0.50 mA/cm2 to 11.2 mA/cm2 after the electrodes were modified with the ZnS coating. The maximum conversion efficiency that was achieved for PbS QDSSCs with a ZnS coating under one sun illumination was 1.92%.