**9. Photovoltaic textile, developments at international level**

The incorporation of polymer photovoltaics into textiles was demonstrated by Krebs et a., (2006) by two different strategies. Simple incorporation of a polyethyleneterphthalate (PET) substrate carrying the polymer photovoltaic device prepared by a doctor blade technique necessitated the use of the photovoltaic device as a structural element71.

The total area of the device on PET was typically much smaller than the active area due to decorative design of aluminium electrode. Elaborate integration of the photovoltaic device into the textile material involved the lamination of a polyethylene (PE) film onto a suitably

Flexible Photovoltaic Textiles for Smart Applications 63

Massachusetts Institute of Technology (MIT) Cambridge, Massachusetts revealed that the integration of solar cell technology in architecture creates designs for flexible photovoltaic materials that may change the way buildings receive and distribute energy. Sheila Kennedy of (MIT) used 3-D modeling software for her solar textiles designs, generating membranelike surfaces that can become energy-efficient cladding for roofs or walls73. Solar textiles

Fig. 12. Patterned polymer cell (with permission)

Fig. 13. Photovoltaic decorative patterns

may also be used like tents as shown in Fig. 14.

transparent textile material that was used as substrate. Plasma treatment of PE-surface allowed the application of a PEDOT electrode that exhibited good adherence. Screen printing of a designed pattern of poly 1,4-(2-methoxy-5-(2-ethylhexyloxy) phenylenevinylene (MEH-PPV) from chlorobenzene solution and final evaporation of an aluminum electrode completed the manufacturing of power generating device. The total area of the textile device was 1000 cm2 (25cm x 40cm) while the active area (190 cm2) was considerably smaller due to the decorative choice of the active material.

Konarka Inc. Lowell, Mass., U.S.A demonstrated a successful photovoltaic fiber. Presently, a German company is engaged with Ecole Polytechnique Fédérale de Lausanne (EPFL) to optimize the fiber properties and weave it into the power-generating fabric. Solar textiles would able to generate renewable power generation capabilities. The photovoltaic fibres are able to woven in fabric form rather than attached or applied on other surfaces where integration remains always susceptible. The structures woven by photovoltaic fibres are able to covert into fabric, coverings, tents and garments.

Patterned photovoltaic polymer solar cells can be incorporated on PET clothing by sewing through the polymer solar cell foil using an ordinary sewing machine. Connections between cells were made with copper wire that could also be sewn into the garment. The solar cells were incorporated into a dress and a belt as shown in Fig.11 (Tine Hertz).

Fig. 11. Textile solar cell pattern designed by Tine Hertz and Maria Langberg of Danmarks Designkole

Shafarman et al., (2003) demonstrated thin film solar cells by using CuInGaSe2 photovoltaic polymers and this film is more suitable for patching onto clothing into different patterns72. The polymer photovoltaics technology is in its infancy stage and many gaps need to be bridged before commercialization. Prototype printing machines are useful to apply PVs on textile surface into decorative pattern as shown in Fig. 11, 12,13.

transparent textile material that was used as substrate. Plasma treatment of PE-surface allowed the application of a PEDOT electrode that exhibited good adherence. Screen printing of a designed pattern of poly 1,4-(2-methoxy-5-(2-ethylhexyloxy) phenylenevinylene (MEH-PPV) from chlorobenzene solution and final evaporation of an aluminum electrode completed the manufacturing of power generating device. The total area of the textile device was 1000 cm2 (25cm x 40cm) while the active area (190 cm2) was

Konarka Inc. Lowell, Mass., U.S.A demonstrated a successful photovoltaic fiber. Presently, a German company is engaged with Ecole Polytechnique Fédérale de Lausanne (EPFL) to optimize the fiber properties and weave it into the power-generating fabric. Solar textiles would able to generate renewable power generation capabilities. The photovoltaic fibres are able to woven in fabric form rather than attached or applied on other surfaces where integration remains always susceptible. The structures woven by photovoltaic fibres are able

Patterned photovoltaic polymer solar cells can be incorporated on PET clothing by sewing through the polymer solar cell foil using an ordinary sewing machine. Connections between cells were made with copper wire that could also be sewn into the garment. The solar cells

Fig. 11. Textile solar cell pattern designed by Tine Hertz and Maria Langberg of Danmarks

Shafarman et al., (2003) demonstrated thin film solar cells by using CuInGaSe2 photovoltaic polymers and this film is more suitable for patching onto clothing into different patterns72. The polymer photovoltaics technology is in its infancy stage and many gaps need to be bridged before commercialization. Prototype printing machines are useful to apply PVs on

textile surface into decorative pattern as shown in Fig. 11, 12,13.

considerably smaller due to the decorative choice of the active material.

were incorporated into a dress and a belt as shown in Fig.11 (Tine Hertz).

to covert into fabric, coverings, tents and garments.

Designkole

Fig. 12. Patterned polymer cell (with permission)

Fig. 13. Photovoltaic decorative patterns

Massachusetts Institute of Technology (MIT) Cambridge, Massachusetts revealed that the integration of solar cell technology in architecture creates designs for flexible photovoltaic materials that may change the way buildings receive and distribute energy. Sheila Kennedy of (MIT) used 3-D modeling software for her solar textiles designs, generating membranelike surfaces that can become energy-efficient cladding for roofs or walls73. Solar textiles may also be used like tents as shown in Fig. 14.

Flexible Photovoltaic Textiles for Smart Applications 65

 In 2002, Konarka became the first company in the United States to license Dr. Michael Grätzel's dye-sensitized solar cell technology, which augmented its own intellectual

 Thuringian Institute of Textiles and Plastics Research (TITK), Breitscheidstraße Rudolstadt Germany, is a technically-oriented research institute, carrying out fundamental and applied research on PV textiles suitable to easily commercialize. The institute supports small and medium-sized enterprises in their innovation works with interdisciplinary scientific knowledge, innovative ideas, and knowledge of the industry

 Professor John Wilson and Dr Robert Mather of School of Textiles and Design, formerly the Scottish College of Textiles have created Power Textiles Ltd, a spin-off from Heriot-Watt University, to develop a process for the direct integration of solar cells on textiles. In a research work at American Institute of Physics, multiwall carbon nanotubes are introduced into poly(3-hexylthiophene) and [6,6] phenyl C61 butyric acid methyl fullerene, bulk heterojunction organic photovoltaic devices after appropriate chemical modification for compatibility with solution processable photovoltaics. To overcome the problem of heterogeneous dispersion of carbon nanotubes in organic solvents, multiwall CNT are functionalized by acid treatment. Pristine and acid treated multiwall carbon nanotubes have been incorporated into the active layer of photovoltaic polymers which results a fill

factor of 0.62 and power harvesting efficiency of 2.3% under Air Mass 1.5 Global75. Dephotex is going to develop photovoltaic textiles based on novel fibre under

 Photovoltaic tents are developed by integration of flexible solar panels made by thin film technology by patching on tent fabric surface. The solar cells can run ventilation systems, lighting and other critical electrical functions, avoiding the need for both

The integration of photovoltaic technology with UV absorption technology will open very smart passages to new product development. However, the above opinion is only a hypothesis of author. The textile materials which are stable against ultraviolet rays are more suitable to work as basic substrate. However, the production and integration of photovoltaic fibres into fabric form will solve many problems concerned about simple incorporation of a polymer photovoltaic on a textile substrate directly or by lamination of a thin layer of PVs onto textile material followed by plasma treatment and application of a PEDOT electrode

The incorporation of polymeric photovoltaics into garments and textiles have been explored new inroads for potential use in ''intelligent clothing'' in more smart ways. Incorporation of organic solar cells into textiles has been realized encouraging performances. Stability issues need to be solved before commercialization of various photovoltaic textile manufacturing techniques. The functionality of the photovoltaic textiles does not limited by mechanical stability of photovoltaics. Polymer-based solar cell materials and manufacturing techniques

power generation capabilities can be tightly integrated

and provision of modern technical infrastructure.

collaboration with European Union.

generators and the fuel to run them.

onto the textile materials.

**10. Conclusions** 

property.

they can produce a photovoltaic fiber. Presently, the Company is working with EPFL to optimize the fiber structure and weave it into the first power-generating fabric. Solar textiles would open up additional application areas for photovoltaics since renewable

Fig. 14. Photovoltaic textile as a tent (with permission)

Fig. 15. A typical example of photovoltaic textile (with permission)


Fig. 14. Photovoltaic textile as a tent (with permission)

Fig. 15. A typical example of photovoltaic textile (with permission)

interest in the development of photovoltaic textiles.

presence in order to develop photovoltaic textiles74.

textiles.

Commission for Technology and Innovation (CTI) Switzerland also exhibited a keen

Thuringian Institute of Textiles and Plastics Research (TITK) registered their remarkable

 J Wilson and R Mather have created Power Textiles Ltd, a spin-off from Heriot-Watt University, Scotland to develop a process for the direct integration of solar cells on

 Konarka is developing solar photovoltaic fabric with joint effort of the university Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland. Konarka has claimed that they can produce a photovoltaic fiber. Presently, the Company is working with EPFL to optimize the fiber structure and weave it into the first power-generating fabric. Solar textiles would open up additional application areas for photovoltaics since renewable power generation capabilities can be tightly integrated


The integration of photovoltaic technology with UV absorption technology will open very smart passages to new product development. However, the above opinion is only a hypothesis of author. The textile materials which are stable against ultraviolet rays are more suitable to work as basic substrate. However, the production and integration of photovoltaic fibres into fabric form will solve many problems concerned about simple incorporation of a polymer photovoltaic on a textile substrate directly or by lamination of a thin layer of PVs onto textile material followed by plasma treatment and application of a PEDOT electrode onto the textile materials.
