Solar cells nanoparticles

Liao JY, He JW, Xu HY, Kuang DB, Su CY (2012) Effect of Ti02 morphology on photovoltaic performance of dye-sensitized solar cells nanoparticles, nanofibers, hierarchical spheres and ellipsoid spheres. J Mater Chem 22(16) 7910-7918... 

Hyun et al. [345] prepared PbS Q-dots in a suspension and tethered them to Ti02 nanoparticles with a bifunctional thiol-carboxyl linker molecule. Strong size dependence due to quantum confinement was inferred from cyclic voltammetry measurements, for the electron affinity and ionization potential of the attached Q-dots. On the basis of the measured energy levels, the authors claimed that pho-toexcited electrons should transfer efficiently from PbS into T1O2 only for dot diameters below 4.3 nm. Continuous-wave fluorescence spectra and fluorescence transients of the PbS/Ti02 assembly were consistent with electron transfer from small Q-dots. The measured charge transfer time was surprisingly slow ( 100 ns). Implications of this fact for future photovoltaics were discussed, while initial results from as-fabricated sensitized solar cells were presented. 

There is no doubt that metallic nanoparticles that have defined sizes and shapes will become key components of a number of novel, highly sophisticated products, the prototypes of which are currently emerging from the industrial R D departments. The outlook is promising for the industrial production of defined 1.4nm metal clusters for use as single electron switches or transistors, for the cost-effective fabrication of ultrapure metallic nanomaterials needed for dye solar cells or sensors, and for the reproducible production of (particularly) efficient and durable... 

Anandan S, Sathish Kumar P, Pugazhenthiran N, Madhavan J, Maruthamuthu P (2008) Effect of loaded silver nanoparticles on Ti02 for photocatalytic degradation of Acid Red 88. Solar Energy Mater Solar Cells 92 929-937... 

Doping is important for semiconductors in order to tune their optical and electrical properties for the potential applications in biotechnology and solar cells [65]. Ag-doped hexagonal CdS nanoparticles were successfully obtained by an ultrasound-assisted microwave synthesis method. Here, the doping of Ag in to CdS nanoparticles induced the evolution of crystal structure from cubic to hexagonal. Further support from photocatalytic experiment also clearly indicates the doping of Ag clusters into the CdS matrix. 

Apart from recapture of the injected electrons by the oxidized dye, there are additional loss channels in dye-sensitized solar cells, which involve reduction of triiodide ions in the electrolyte, resulting in dark currents. The Ti02 layer is an interconnected network of nanoparticles with a porous structure. The functionalized dyes penetrate through the porous network and adsorb over Ti02 the surface. However, if the pore size is too small for the dye to penetrate, that part of the surface may still be exposed to the redox mediator whose size is smaller than the dye. Under these circumstances, the redox mediator can collect the injected electron from the Ti02 conduction band, resulting in a dark current (Equation (6)), which can be measured from intensity-modulated experiments and the dark current of the photovoltaic cell. Such dark currents reduce the maximum cell voltage obtainable, and thereby the total efficiency. 

The chapters cover the following areas (i) use of coordination complexes in all types of catalysis (Chapters 1-11) (ii) applications related to the optical properties of coordination complexes, which covers fields as diverse as solar cells, nonlinear optics, display devices, pigments and dyes, and optical data storage (Chapters 12-16) (iii) hydrometallurgical extraction (Chapter 17) (iv) medicinal and biomedical applications of coordination complexes, including both imaging and therapy (Chapters 18-22) and (v) use of coordination complexes as precursors to semiconductor films and nanoparticles (Chapter 23). As such, the material in this volume ranges from solid-state physics to biochemistry. 

It is well known that Ti02 is widely used in cosmetics, solar cells, batteries, additives in toothpaste and white paint, and others. Recently, there is a considerable interest in using Ti02 nanoparticles as a film-forming material since they have high... 

Figure 11.5 Essential features of a dye-sensitised solar cell based on sensitiser-coated Ti02 nanoparticles...

Figure 3.31. Organic solar cell with the molecular glass Spiro-MeOTAD as the solid-state electrolyte. The photosensitive ruthenium dye is attached as a monolayer to Ti02 nanoparticles, thus forming a large active area for photoinduced electron transfer.

Narayanan, R., M. Deepa, and A.K. Srivastava, Nanoscale connectivity in a Ti02/CdSe quantum dots/functionalized graphene oxide nanosheets/Au nanoparticles composite for enhanced photoelectrochemical solar cell performance. Physical Chemistry Chemical Physics, 2012.14(2) p. 767-778. 

Fan, G.-Q., et ah, Plasmonic-enhanced polymer solar cells incorporating solution-processable Au nanoparticle-adhered graphene oxide. Journal of Materials Chemistry, 2012. 22(31) ... 

Tjoa, V., et al., Facile photochemical synthesis ofgraphene-Pt nanoparticle composite for counter electrode in dye sensitized solar cell. ACS Applied Materials Interfaces, 2012. 

Poudel, P. Qiao, Q., One dimensional nanostructure/nanoparticle composites as photoanodes for dye-sensitized solar cells. Nanoscale 2012,4 2826-2838. 

Jang, Y. H. Xin, X. Byun, M. Jang, Yu J. Lin, Z. Kim, D. H., An Unconventional Route to High-Efficiency Dye-Sensitized Solar Cells via Embedding Graphitic Thin Films into Ti02 Nanoparticle Photoanode. Nano Letters 2012,12 479-485. 

Wang C, Bahnemann DW, Dohrmann JK (2000) A novel preparation of iron-doped Ti02 nanoparticles with enhanced photocatalytic activity. Chem Commun 16 1539-1540 Wang Y, Hao Y, Cheng H, Ma H, Xu B, Li W, Cai S (1999) The photoelectrochemistiy of transition metal-ion-doped Ti02 nanociystalline electrodes and higher solar cell conversion efficiency based on Zn -doped Ti02 electrode. J Mater Sci 34 2773-2779... 

Copper selenide is also used in solar cells [200]. TOPO-capped CuSe nanoparticles were synthesized from Cu(Se2CNEt2)2 using a single-source method [201]. Copper selenide nanoparticles have also been prepared and XPS spectra, valence bands and Auger transitions reported for the molecular clusters Cui46Se73(PPh(3))(202) and Cu2Se [203]. Photoemission features were reported for both species. 

In photo-catalytic and solar energy conversion devices, the absorption of a photon results in the generation of electrons and holes, which, upon separation, can provide an electric potential or trigger chemistry. The efficiency of these devices is frequently determined by the transport of the charges following photo-generation. In particular, for TiC>2-based dye-sensitized solar cells, it has been demonstrated that the efficiency is limited by electron transport through TiC>2 nanoparticles [1]. 

Ultimately an understanding of electron transfer processes in dye-sensitized solar cells must be expressed in terms of a model which takes the specific nature of metal oxide surfaces into account [97]. Moreover, the nanostructured devices often involve oxide nanoparticles which approach the limit where quantum-size effects become important. It would be a great step forward if this could be incorporated into an electron-transfer model. 

In recent years, ET dynamics at the sensitizer-semiconductor nanoparticle interface has been intensively studied [51,52]. In addition to its fundamental importance, understanding the interfacial ET is also crucial to the development of numerous nanoparticle-based devices, such as molecular electronics [53,54] and solar cells based on composites of molecular and nanostructured semiconductor components [55-57],... 

Fig. 5 4. The structure of DTB-Pe, the way it adsorbs on TiOz surface and the schematic representation of the structure of the thin film layer of Ti02 nanoparticles on top of the electrode in a dye-sensitized solar cell, with dye molecules adsorbed on it. (Reprinted with permission from Ref. [58]. Copyright 2001 American Chemical Society.)...

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