Photovoltaic polymeric solar cells

Alternating copolymer 20 derived from 2,7-dibenzosilole and 4,7-dithienyl-2,1,3-benzothiadiazole is an outstanding polymeric electron donor in photovoltaic cells.37 With an active layer made up of copolymer to PCBM in a 1 2 ratio, the solar cell displays a high short-circuit current of 9.5 mA/cm2, an open-circuit voltage of 0.9 V, and a fill factor of 50.7%, under illumination of an AM 1.5 solar simulator at 80 mW/cm2. The calculated energy conversion efficiency is 5.4%, which is one of the highest efficiencies so far reported for polymeric photovoltaic cells. 

H. Spanggaard, F.C. Krebs, A brief history of the development of organic and polymeric photovoltaics, Solar Energy Materials and Solar Cells 83 (2004) 125-146. 

Keywords Quantum confinement, quantum-confined nanomaterials (QCNs), quantum dots (QDs), tetrapods, nanocrystals, nanorods, carbon dots (C-dots), graphene quantum dots (GQDs), CdSe, CdS, CdTe, PbS, PbSe, blends, nanocomposites, in-situ polymerization, organic photovoltaics (OPVs), organic light-emitting diodes (OLEDs), dye-sensitized solar cells (DSSCs)... 

Keywords Solar cells, organic photovoltaics (OPVs), quantum confinement effect (QCE), conjugated polymers, nanocomposites, blends, quantum dots (QDs), nanocrystals, nanorods, carbon nanotubes (CNTs), graphene, nanoparticles, alternating copolymers, block copolymers, exdton diffusion length, short-circuit current, open-circuit voltage, fill factor, photoconversion efficiency, in-situ polymerization... 

This Chapter sets out to make the case for the use of textiles, and the polymeric fibres that comprise them, as substrates for photovoltaic devices - or solar cells. Apart from the use of an endless energy source, there are other advantages too a clean, silent technology, very small maintenance costs, and an attractive technology for remote areas where there is no electrical supply from a grid. It could also be a key technology for quick electrical supply to regions struck by sudden natural disasters, such as earthquakes, hurricanes and floods. 

These examples of electrochromic devices serve to display the breadth of their applicability to any number of systems. Polymeric electrochromics, particularly those based on thiophene and its derivatives, show promise for use in display technologies. The processability of many of these systems makes them specifically suited for large-area applications, such as smart windows, billboards or organic photovoltaic cells (solar cells), which currently suffer from large environmental and practical costs when fabricating large-area devices. 

A systematic study of the effect of molecular weight on the photovoltaic performance has also been performed on poly(3-hexadecylthienylene vinylene) synthesized by ADMET polymerization [164]. The molecular weights of the polymers ranged from 6.0x10 to 3.0 X lO gmoD, and were incorporated into bulk heterojunction solar cells with [6,6]-phenyl-Cg -butyric acid methyl... 

JIN 13b] Jin X., Yu X., Zhang W. et al., Synthesis and photovoltaic properties of main chain polymeric metal complexes containing 8-hydroxyquinoline metal complexes conjugating alkyl fluorene or alkoxy benzene by C=N bridge for dye-sensitized solar cells , Polymer Composites, vol. 34, no. 10, pp. 1629-1639, 2013. 

LEE 11] Lee S.-M., Lee S.-B., Kim K.-H. et al., Syntheses and photovoltaic properties of polymeric sensitizers using thiophene-based copolymer derivatives for dye-sensitized solar cells . Solar Energy Materials and Solar Cells, vol. 95, no. l,pp. 306-309,2011. 

YU 13] Yu X., Jin X., Tang G. et al., D-ji-A dye sensitizers made of polymeric metal complexes containing 1,10-phenanthioline and alkylfluoiene or alkoxybenzene synthesis, characterization and photovoltaic performance for dye-sensitized solar cells , European Journal of Organic Chemistry, vol. 2013, no. 26, pp. 5893-5901,2013. 

Thin-film solar cells are without doubt one of the most spectacular application (except thin-film transistors) of a-Si H films obtained by plasma polymerization processes. Since the demonstration of the first a-Si H photovoltaic devices at RCA laboratories in 1976 (Carlson Wronski, 1976) there has been remarkable progress in the development of a-Si H solar cells, spurred, first of all, by the wide demand for a low cost, clean and safe energy (Mueller, 2009). 

The main reasons for the low efficiencies are the incomplete absorption of the solar spectrum by any single material which serves as a colorant. Self-absorption of the fluorescence by the emitting colorant. Critical cone losses of the reemitted centers, absorption and scattering of the host materials, lack of good contact between the LSC and the photovoltaic cell. Reflection of light from the metallic surfaces of which the electrical contacts are made. The decrease of performance efficiency of the collectors made of organic dyes with time are a result of photodecomposition of the colorant and polymeric host material. 

In evaporation-intercalation devices solar energy conversion would, at least in the more efficient case of a thermal system, not be converted by exciting electrons and rapidly separating them from holes, but by transferring atoms or molecules across a phase boundary by evaporation which is usually a very efficient process. It is, consequently, neither necessary to use materials which are well crystallized like those developed for photovoltaic cells nor is it necessary to prepare sophisticated junctions. A compacted polycrystalline sheet of a two-dimensional material which is on one side placed in contact with an electrolyte, sandwiched between the layer-type electrode and a porous counter electrode, as it is used in fuel cells, would constitute the central energy conversion unit. Some care would have to be taken to choose an electrolyte which is suitable for intercalation reactions and which is not easily evaporated through leaks in the electrodes. Thin layers of polymeric or solid electrolytes would seem to be promising. 

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