**6.1.1 Manufacturing of photovoltaic fibres as per Bedeloglu et al.,57-58 method**

Bedeloglu et al., have used nontransparent PP as substrate. The PP tape was washed using methanol, isopropanol and water and then dried in N2 atmosphere. Thermal evaporation technique was used to deposit 100nm thick Ag contact layer on PP substrate. A filtered solution of PEDOT: PSS, chemical structure shown in Fig.7, in 5% dimethyl sulfoxide (DMSO) and stirred with 0.1% Triton X-100 to increase the thermal conductivity and cohesiveness properties. Stirred mixture of PEDOT: PSS were deposited on cleaned PP tapes at a thickness of 200 nm by dip coating technique. A blend of P3HT as conjugated polymer and PCBM was stirred upto 24h in chlorobenzene and then dip coated with thickness of 200 nm on top of PEDOT: PSS layer. Finishing of all PV structures was completed in vacuum chambers. An aluminium contact layer of approximately 3 nm thickness was deposited followed by 7nm thick Ag layer as anode. The purpose of Al layer was to avoid short circuiting between Ag and PEDOT: PSS films. The resultant photovoltaic fibre is shown in Fig.8.

Fig. 8. Schematic representation of Photovoltaic fibre

Flexible Photovoltaic Textiles for Smart Applications 57

Plasma treatment was followed by application of PEDOT electrode deformation by spray painting of an inhibited mixture of Iron (III) Tosylate and 3,4-Ethylene-dioxythiopene (EDT) through an aluminum mask. As the temperature reaches 50°C inhibitors are started to evaporate and polymerization of EDT initiated. After completing the polymerization, the PEDOT-coated textile was washed in cold water twice to washout excess tosylate, Iron (II)

The materials that can generate electricity by photon conversion are loaded with fibres,

Chlorobenzene was used to get the solution of MEH-PPV of 3.5gL-1. The solution was filtered through a filter of 2.7μm filter and coated on polyethylene terephthalate- Indium tin oxide (PET-ITO) substrate by doctor blade coating system. Consequently a homogeneous red colour film is coated on PET-ITO substrate. Cholorobenezene solution of 25gL-1 was used to get printed pattern of polymer by means of screen-printing. The masks were prepared by using threads of 27 micron diameter with 140, 180,200 and 220 fibres cm-1 mesh. Finally, the printed substrates were dried in absence of sunlight. Photovoltaic device was prepared by following manner. The PET-ITO-MEHPPV substrates were incorporated behind a mask and a layer of C60 and aluminium was deposited by thermal evaporation technique. After completing the evaporation the device was laminated on 100 micron PET substrate on electrode side. The screen printed photovoltaic textile was mounted on large evaporator and kept the distance between thermal source and substrate 65 cm. The PV textile holder was rotated at 30 rpm. The aluminium electrodes were prepared in the form of 300 nm thick layers. The evaporation chamber was filled with dry nitrogen after completing the 30 min cooling. Electrodes were integrated with textile substrate by using silver epoxy62.

Characterization of various photovoltaic textiles is essential to prove its performance before send to the market. Various characterization techniques collectively ensures the perfect

Scanning electron microscope is used to investigate the thickness and morphology of various donor, acceptor layers. Scanning electron microscopes from LEO Supra 35 and others can be used to measure the existence and thickness of various coated layers on various textile surfaces at nanometer level. Various layers on photovoltaic fibres become clearly visible with 50000X magnification. The thickness of the layers can be seen from SEM photographs by bright interface line between the polymer anode and the photoactive

In order to characterize the Photovoltaic fibres open circuit voltage, short circuit current density, current and voltage at the maximum power point under an illumination of 100

In order to calculate the Photovoltaic efficiency of Photovoltaic textiles, current verses voltage study is essential. To achieve this target a computer controlled sourcemeter equipped with a solar simulator under a range of illumination power is required with proper calibration. All photoelectrical characterizations are advised to conduct under nitrogen or argon atmosphere

and inhibitor residuals and finally annealed in air at 50°C for 2 hour.

yarns and textile structures inherently to offer PV effect.

**7. Characterization of photovoltaic textiles** 

layer.

**7.2 Current and voltage** 

mW/cm2 are carried out.

achievement of the targets to manufacture the desired product.

**7.1 Thickness and morphology of photovoltaic textiles** 

A group of Turkish scientists has standardized a photovoltaic fibre manufacturing process. A monofilament supply cope is used to supply the basic filament for PV fibre manufacturing. This monofilament is cleaned in a bath by methanol solution and then further clean up by isopropanol solution in second bath. The cleaned fibre surface is washed with distill water followed by drying with dry nitrogen flow. The fibre is immersed in fourth bath containing mixture of PEDOT: PSS followed by oven drying at 50°C for 3 hr. The coated fibres are further immersed in another subsequent bath containing photoactive material solution and then dried out at 50°C for 15 min in oven. After drying, deposition of metal electrode takes place on fibre surface followed by deposition of anti-reflective materials by appropriate deposition technique. Finally a protective layer is laminated on fibre surface. In consequence of this process, a photovoltaic fibre is manufactured and become ready for power harvesting.

Fig. 9. Manufacturing process of Photovoltaic fibre as suggested by Bedeloglu et al.21

### **6.2 PV textiles by patching (attachment of PV cells to existing textile structures)**

Under this technology a solar cell is manufactured separately and then patched onto textile structure by different ways. Thin film solar cells with adequate flexibility can be patched successfully on textile surfaces to impart PV effect. This technique is most appropriate to easily develop both small and large area structures with low cost, and light weight.

In a typical approach thin layers of polymer photovoltaics are laminated onto a textile substrate followed by plasma treatment and coating of PEDOT electrode. Subsequent screen printing of the active material and evaporation of the ultimate electrode finished the polymer photovoltaic that is fully integrated into the textile material59.

Poly 1,4-(2-methoxy-5-(2-ethylhexyloxy))phenylenevinylene (MEH-PPV) was synthesized by polymerization of α,α'-dibromo-2-methoxy-5-(2-ethylhexyloxy) xylene as described by Neef and Ferraris. The purified MEH-PPV was characterized and found the Mw of 249,000 g mol-1 , polydispersity of 5.46 and a peak molecular weight Mp of 157,500 g mol-1. A polyethylene terephthalate (PET) film of thickness 200 μm covered with 50 Ω2 ITO layer was iched by 20% HCL and 5%HNO3. A 250 μm thick polyethylene film was thermally laminated on polyethylene terephthalate (PET) surface. Both PET and PE surfaces was plasma treated using a 350-1 low power 3-phase AC plasma system as prescribed by Jensen and Glejbol (2003) in order to obtain optimum etching to get appropriate adherence with textile substrates60-61.

A group of Turkish scientists has standardized a photovoltaic fibre manufacturing process. A monofilament supply cope is used to supply the basic filament for PV fibre manufacturing. This monofilament is cleaned in a bath by methanol solution and then further clean up by isopropanol solution in second bath. The cleaned fibre surface is washed with distill water followed by drying with dry nitrogen flow. The fibre is immersed in fourth bath containing mixture of PEDOT: PSS followed by oven drying at 50°C for 3 hr. The coated fibres are further immersed in another subsequent bath containing photoactive material solution and then dried out at 50°C for 15 min in oven. After drying, deposition of metal electrode takes place on fibre surface followed by deposition of anti-reflective materials by appropriate deposition technique. Finally a protective layer is laminated on fibre surface. In consequence of this process, a photovoltaic fibre is manufactured and

Fig. 9. Manufacturing process of Photovoltaic fibre as suggested by Bedeloglu et al.21

**6.2 PV textiles by patching (attachment of PV cells to existing textile structures)**  Under this technology a solar cell is manufactured separately and then patched onto textile structure by different ways. Thin film solar cells with adequate flexibility can be patched successfully on textile surfaces to impart PV effect. This technique is most appropriate to

easily develop both small and large area structures with low cost, and light weight.

polymer photovoltaic that is fully integrated into the textile material59.

In a typical approach thin layers of polymer photovoltaics are laminated onto a textile substrate followed by plasma treatment and coating of PEDOT electrode. Subsequent screen printing of the active material and evaporation of the ultimate electrode finished the

Poly 1,4-(2-methoxy-5-(2-ethylhexyloxy))phenylenevinylene (MEH-PPV) was synthesized by polymerization of α,α'-dibromo-2-methoxy-5-(2-ethylhexyloxy) xylene as described by Neef and Ferraris. The purified MEH-PPV was characterized and found the Mw of 249,000 g mol-1 , polydispersity of 5.46 and a peak molecular weight Mp of 157,500 g mol-1. A polyethylene terephthalate (PET) film of thickness 200 μm covered with 50 Ω2 ITO layer was iched by 20% HCL and 5%HNO3. A 250 μm thick polyethylene film was thermally laminated on polyethylene terephthalate (PET) surface. Both PET and PE surfaces was plasma treated using a 350-1 low power 3-phase AC plasma system as prescribed by Jensen and Glejbol (2003) in order to obtain optimum etching to get appropriate adherence with

become ready for power harvesting.

textile substrates60-61.

Plasma treatment was followed by application of PEDOT electrode deformation by spray painting of an inhibited mixture of Iron (III) Tosylate and 3,4-Ethylene-dioxythiopene (EDT) through an aluminum mask. As the temperature reaches 50°C inhibitors are started to evaporate and polymerization of EDT initiated. After completing the polymerization, the PEDOT-coated textile was washed in cold water twice to washout excess tosylate, Iron (II) and inhibitor residuals and finally annealed in air at 50°C for 2 hour.

The materials that can generate electricity by photon conversion are loaded with fibres, yarns and textile structures inherently to offer PV effect.

Chlorobenzene was used to get the solution of MEH-PPV of 3.5gL-1. The solution was filtered through a filter of 2.7μm filter and coated on polyethylene terephthalate- Indium tin oxide (PET-ITO) substrate by doctor blade coating system. Consequently a homogeneous red colour film is coated on PET-ITO substrate. Cholorobenezene solution of 25gL-1 was used to get printed pattern of polymer by means of screen-printing. The masks were prepared by using threads of 27 micron diameter with 140, 180,200 and 220 fibres cm-1 mesh. Finally, the printed substrates were dried in absence of sunlight. Photovoltaic device was prepared by following manner. The PET-ITO-MEHPPV substrates were incorporated behind a mask and a layer of C60 and aluminium was deposited by thermal evaporation technique. After completing the evaporation the device was laminated on 100 micron PET substrate on electrode side. The screen printed photovoltaic textile was mounted on large evaporator and kept the distance between thermal source and substrate 65 cm. The PV textile holder was rotated at 30 rpm. The aluminium electrodes were prepared in the form of 300 nm thick layers. The evaporation chamber was filled with dry nitrogen after completing the 30 min cooling. Electrodes were integrated with textile substrate by using silver epoxy62.
