Title of Invention

A PROCESS FOR PREPARING POLYMERIC BULKHETEROJUNCTIONS FROM CONDUCTING PREVULCANIZED NATURAL RUBBER LATEX C60 (BUCKMINSTERFULLERENCE) INTERPENETRATING NANOCOMPOSITES AS A NOVEL MATERIAL FOR FABRICATING PLASTIC SOLAR CELLS

Abstract A polymer bulk hetrojunction ,which comprises a conducting polymer component and a fullerene component .The conducting polymer component is formed from the latex of natural rubber by doping ,which is prevulcanized by gamma irradiation , and is blended with the fullerene component. C60 in toluene or cyclohexane solution to form an interpenetrating network composite. Interpenetrating composite bulk hetrojunctions produced by the method of invention are useful for preparing plastic solar cells.
Full Text BACKGROUND OF THE INVENTION
[000\]l. Field of invention
[0002] The present invention relates to a process for producing polymeric bulk
heterpjunctions from conducting pre-vulcanized NR latex-C60 interpenetrating
nanopomposites and fabrication of a plastic solar cell.
[0003] 2. Description of the Prior Art
[0004] The advantages of plastic solar cells over silicon-based solar cells are well known in the art. Since they are moldable and lightweight, they can be installed in a variety of shapes and hence deployed more widely than silicon based solar panels. Polymer photovoltaic panels can be manufactured at low cost by continuous polymer coating process, which is less expensive than silicon based production. However a major disadvantage of plastic solar cells besides its low energy conversion efficiency is the material cost and fabrication difficulties.
[0005] According to the recent knowledge, nanostructuring of polymer blends via the formation of interpenetrating networks of donor molecules such as conjugated conducting polymers and acceptor molecules such as fullerenes can make the PV cell active layer sand^ched between two different electrodes. Nanoscale phase segregation is observed and functions as a bulk heterojunction. The photoinduced electron transfer from the light-absorbing polymer to the fullerene occurs with an astonishingly short period of time 300 femtosecond. This is so fast that no disturbing process can compete. Hence, the efficiency of photoinduced electron transfer approaches 100 %. Moreover the lifetime of the electron transferred state being very long on a molecular scale i.e., 10-3 -10-5 seconds allowing for quite some time for the charges to be transported to the corresponding electrodes.
[0006] Thus the optimization of the nanomorphology of blends, a conducting conjugated polymer with fuUerene is a new field with enormous potential for plastic PV devices. [0007] However, the great nanotechnological challenge is how to obtain, the ordered interpenetrating D-A network structure in the film.

[0008] Currently, the donor p-type conducting polymer used for preparing nanostructurea interpenetrating network blends with C60 for this purpose is costly materials like MEH-PPV etc. Thus the art has continued to seek an economical conducting polymeric material in place of such costly elements and simple process for preparing bulk heterojunction.
SUMMARY OF THE INVENTION
[0009] Accordingly the object of this invention is to develop a cheap conducting polymer - C60 interpenetrating network films for the use in plastic solar cells. [0010] According to this invention, there is provided a process for preparing interpenetrating networks of conducting pre-vulcanised NR latex and fullerene in the plane of the film and function as a bulk heterojunction. The pre-vulcanised (y-irradiated) latex is obtained from fresh latex taken in a rotating vessel system and prevulcanized by gamma (60C, 7.38 x 1013 Bq) radiation source at a rotating speed of 10 rev min-1 at a temperature of 25oC. The dose rate is 0.565 kGy h-1 (total dose = 12). 2-ethylhexylacrylate and CCI4 are used as the sensitizers. The pre-vulcanised latex of varying DRC of 50, 53.8 and 55 % is stabilized by adding sterric stabilizer starch or Do-decylbenzene sulfonic acid (DBSA) at different weight fractions of 2% weight/weight (w/w) or 5% weight/weight (w/w) of latex that sterically prevents the latex particles from coagulation. The solution is stirred with different weight fractions ( 5 % weight/weight (w/w) , 10 % weight/weight orl5 % weight/weight of latex) of fullerene in toluene or cyclohexane for about 5 hours followed by the addition of iodine in toluene or cyclohexane at two different [C=C]/[l2] molar ratios of 8 orl2. A nanostructured blend is formed because the polymer does not mix well due to low entropy of mixing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As follows is a more detailed description of the present invention
[0011] In this description, the term "pre-vulcanization" refers to the partial cross linking of the latex prior to any chemical treatment and this is achieved by exposing the fresh latex to gamma irradiation under the conditions described above. This latex can ensure enough mechanical strength to the fabricated latex films.
[0012] A number of methods such as sulfur vulcnaisation, peroxide vulcanisation, chemical grafting, gamma-irradiation etc are well known for chemical modification of

NR latex. In the present invention the process of gamma irradiation is selected for pre-vulci^nisation since it does not involve any chemical ingredients which may adversely affect the doping reaction. [0013] Sterric Stabilisers
[0014] The sterric stabilisers starch or DBS A is used to stabilize the latex from coagulation on addition of any foreign materials to the latex solution and here iodine-toluene or iodine - cyclohexane solution are the foreign materials. The adsorption of the stabiliser molecule to the rubber moieties is in fact the probable mechanism for the stabilization of the latex.
[0015] In the present invention the doping reaction was carried out for each different quantit}' of stabilizer (between 2- 5 % weight/weight of latex)
[0016] There are no restrictions on the methods used to add the stabilizer, and typically used methods include addition of the stabilizer directly while stirring or adding the stabilizer as a water based solution.
[0017] Ceo is well known as a typical n-type polymer and is used in the present invention.
[0018] In the present invention the fullerene- toluene or fullerene- cyclohexane solution
is added to the latex solution and is carried out for different weight fractions of fullerene
(between 5-15 % weight/weight of latex)
[0019] Stirring of stabilized latex solution with the fullerene mixture results in the
formation of bulk heteroj unctions.
[0020] Methods for measuring the molar ratio of C=C double bonds of Polyisoprene in
the reaction medium are well known. The molar ratio is calculated using the basic
equation
[C^C] = weight of latex taken in g /ml x 1000
68 [0021] With the mixture undergoing constant stirring, a pre-determined quantity of a predetermined doping agent (iodine at 0.00623 g/ml) in a pre-determined solvent (toluene or cyclohexane) was added and the doping reaction was allowed to proceed. The molar ratio of iodine is calculated from the equation [I2] = weight of iodine taken in g/ml x 1000
258

[0022] Here the [C=C] /[I2] is calculated to be 8. After 24 h, part of the solution was
casted on glass substrates and dried under dynamic vacuum (10"' torr). Rest of the doped
solution was coated at subsequent time intervals of 24 h each up to 240 h.
[0023] Using the same method, the doping reaction was carried out for different
concentrations of iodine (0.0046 g/ml)
[0024] The decrease in iodine concentration results in an increase in the ratio [C=C] /[k]
to 12 resulting in lower doping rate as inferred from the color changes.
[0025] There are no particular restrictions on the doping time of the system and typical
time values are from 24 h to 240 h.
[0026] In a production process of the present invention, the reaction was carried out with
latex of different dry rubber content (DRC) of 50, 53.8 and 55%.
[0027] Next, the polymer fabrication of a bulk heterojinction photovoltaic (PV) cell of
the present invention will be illustrated. The polymer PV device is fabricated using
interpenetrating networks of intrinsically conducting natural rubber latex pre-vulcanised
by gamma radiation - C60 composite film sandwiched between a pair of electrodes
composed of an anode and a cathode and at least one of which is transparent or semitransparent.
[0028] As the polymer film is formed from a solution, coating methods such as a spin coating method, solution casting method and dip coating method can be used. [0029] The substrate forming the polymer PV of the present invention may preferably be that does not change in forming an electrode and layers of organic materials, and there are exemplified glass, plastics, polymer film, silicon substrates and the like. In the present invention, it is preferable that an anode is transparent or semitransparent, and as the material of this anode, electron conductive metal oxide films, semitransparent metal thin films and the like are used. Specifically, there are used indium oxide, zinc oxide, tin oxide, and films (NESA and the like) fabricated by using an electron conductive glass composed of indium tin oxide (ITO), indium zinc oxide and the like, which are metal oxide complexes, and gold, platinum, silver, copper and the like are used, and among them, ITO, indium- zinc -oxide, tin oxide are preferable.

[0030] The thickness of the anode can be appropriately selected while considering transmission of a light and electric conductivity, and for example, from 10 nm to 10µ.m, preferably from 20 nm to 1µm, further preferably from 50 nm to 500 nm. [0031] As the material of a cathode used in the polymer PV of the present invention, that having lower work function is preferable. For example, there are used metals such as lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbiimi and the like, or alloys comprising two of more of them, or alloys comprising one or more of them with one or more of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten and tin, graphite or graphite intercalation compounds and the like. Examples of alloys include a magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, calcium-aluminum alloy and the like. The cathode may be formed into a laminated structure of two or more layers. The thickness of the cathode can be appropriately selected while considering transmission of a light and electric conductivity, and for example, from 10 nm to 10 µm, preferably from 20 nm to 1 µm, further preferably from 50 nm to 500 nm. [0032] As the method for fabricating a cathode, there are used a vacuum vapor deposition method is used. EXAMPLES [0033] The following examples further illustrate the present invention in detail.
[0034] Synthesis of conducting films of natural rubber - €50 interpenetrating network composite
[0035] 0.25 g of latex (DRC = 53.8%) is stabilized by adding 0.005 g (2 %w/w) of starch. The latex solution remains as a colloidal solution. 0.0125g (5% w/w) of C60 - toluene solution is added and stirred for 5 hours. Then the I2 doping reaction is carried out by adding iodine- toluene solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere. The progress of the doping reaction can be inferred by the colour changes from purple to dark brown and from conductivity measurements. Thin films spin coated on glass substrates at different time intervals of 24,

48. 72, 96 and 240 h and dried under dynamic vacuum are used for conductivity studies. The conductivity was found to increase from giga ohms to kilo ohms with the increase in doping time. Comparative Examples
[0036] 0.25 g of latex (DRC = 53.8%) is stabilized by adding 0.005 g (2%w/w) of starch. The latex solution remains as a colloidal solution. 0.025g (10% w/w) of C60 -cyclohexane solution is added and stirred for 5 hours. Then the h doping reaction is carried out by adding iodine- cyclohexane solution (0.00623 g/ml) at a [C==C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere. The progress of the doping reaction can be inferred by the colour changes from purple to dark brown and from conductivity measurements. Thin films spin coated on glass substrates at different time intervals of 24, 48, 72, 96 and 240 h and dried under dynamic vacuum are used for conductivity studies. The conductivity was found to increase from giga ohms to kilo ohms with the increase in doping time. However the conductivity was found to be lower than the above group for the same doping period.
[0037] 0.25 g of latex (DRC = 53.8%) is stabilized by adding 0.005 g (2 % w/w) of starch. 0.0375 g (15% w/w)) of C60 in toluene was added and stirred for 5 hours. Then the I2 doping reaction is carried out by adding iodine- toluene solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere. Flexible conducting bulk heterojunction films were obtained and the resistivity values were lower than the above results as expected.
[0038] 0.0125 g (5% w/w) of starch is added to 0.25 g of latex (DRC = 53.8%) followed by the addition of 0.0125 g (5%w/w) of C60 in toluene with continuous stirring for 5 hours. The I2 doping reaction is carried out by adding iodine- toluene solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere. The procedure is same as for the above examples. The colour changes from purple to dark brown and the progress of the doping reaction was inferred from the conductivity measurements.

[0039]: 0.0125 g (5% w/w) of starch is added to 0.25 g of latex (DRC -= 53.8 %) followed by the addition of 0.025 g (10% w/w) of C60 in toluene with continuous stirring for 5 hours .The I2 doping reaction is carried out by adding iodine- toluene solution (0.00623 g/ml) at a [C=C] /[h] molar ratio of 8. The solution is stirred under nitrogen atmosphere. The procedure is same as for the above examples. The resistivity values were obtained in the mega ohms range.
[0040] 0.01.25 g (5%w/w) of starch is added to 0.25 g (DRC = 53.8%) of latex, followed by the addition of 0.0375 g (15%w/w) of Ceo in cyclohexane with continuous stirring for 5 hours .The I2 doping reaction is carried out by adding iodine- cyclohexane solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere. The procedure is same as for the above examples. The characteristic colour changes and the resistivity changes were comparable to the above results. [0041] 0.0125 g (5%w/w) of starch is added to 0.25 g (DRC = 53.8%) of latex, followed by the addition of 0.0375 g (15%w/w) of C60 in toluene with continuous stirring for 5 hours .The I2 doping reaction is carried out by adding iodine- toluene solution (0,0046 g/ml) at a [C=C] /[I2] molar ratio of 12. The solution is stirred under nitrogen atmosphere. The procedure is same as for the above examples. The characteristic colour changes and the resistivity changes were comparable to the above results.
[0042]: 0.0125 g (5% w/w) of starch is added to 0.25 g of latex (DRC = 50 %) followed by the addition of 0.0125 g (5%w/w) of C60 in toluene with continuous stirring for 5 hours. The I2 doping reaction is carried out by adding iodine- toluene solution (0.0046 g/ml) at a [C=C] /[I2] molar ratio of 12. The solution is stirred under nitrogen atmosphere. The procedure is same as for the above examples. The colour changes from purple to dark hrovm and the progress of the doping reaction was inferred from the conductivity-measurements.
[0043] 0.0125 g (5% w/w) of starch is added to 0.25 g of latex (DRC = 55 %) followed by the addition of 0.0125 g (5%w/w) of Ceo in cyclohexane with continuous stirring for 5 hours. The I2 doping reaction is carried out by adding iodine- cyclohexane solution (0.0046 g/ml) at a [C==C] /[I2] molar ratio of 12. The solution is stirred under nitrogen

atmosphere. The procedure is same as for the above examples. The colour changes from purple to dark brown and the progress of the doping reaction was inferred from the conductivity measurements. A highly interpenetrating networks of intrinsically conducting natural rubber - C6o bulkheterojunction was formed and thus nano composite films were easily casted on to various substrates.
[0044]: 0.25 g of latex (DRC = 53.8%) is stabilized by adding 0.005 g (2%w/w) of starch. The latex solution remains as a colloidal solution. 0.025g (10% w/w) of C60 --cyclohexane solution is added and stirred for 5 hours. Then the h doping reaction is carried out by adding iodine- cyclohexane solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere at a higher temperature of 50oC. The rate of the doping reaction was increased as inferred from conductivity measurements. Thin films spin coated on glass substrates at different time intervals of 24, 48, 72, 96 and 240 h and dried under dynamic vacuum are used for conductivity studies. The conductivity was found to increase from giga ohms to kilo ohms with the increase in doping time. A nanocomposite thin film of natural rubber- C60 was obtained.
[0045] 0.25 g of latex (DRC = 53.8%) is stabilized by adding 0.005 g (2% w/w) of DBSA. The latex solution remains as a colloidal solution. 0.0125 g (5% w/w) of C60 in toluene is stirred with the latex solution for 5 hours, then the I2 doping reaction is carried out by adding iodine- toluene solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere at a temeparture of 20o C. The progress of the doping reaction can be inferred by the color change fi'om purple- dark brown and from conductivity measurements. Thin films spin coated on glass substrates at different time intervals of 24, 48, 72, 96 and 240 h and dried under dynamic vacuum are used for conductivity studies.
[0046] 0.25 g of latex (DRC = 53.8%) is stabilized by adding 0.005g (2% w/w) of DBSA. 0.025 g (10%w/w) of C60 in cyclohexane is stirred with the latex solution for 5 hours. Then the I2 doping reaction is carried out by adding iodine- cyclohexane solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 12. The solution is stirred under nitrogen

atmosphere Flexible conducting nanocomposite films were obtained and the resistivity values were comparable to films obtained for the above example.
[0047] 0.25 g of latex (DRC = 53.8%) is stabilized by adding O.OOSg (2% w/w) of DBSA. 0.0375 g (15% w/w) of C6o in toluene is stirred with the latex solution for 5 hours. Then the I2 doping reaction is carried out by adding iodine- toluene solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere. Flexible conducting bulkheteroj unction films were obtained and the resistivity values were comparable to films obtained for the above example.
[0048] 0.0125 g (5% w/w) of DBSA is added to 0.25 g of latex (DRC = 53.8 %). 0.0125 g (5% w/w) of C60 in cyclohexane is stirred with the latex solution for 5 hours. The I2 doping reaction is carried out by adding iodine- cyclohexane solution (0.0046 g/ml) at a [C=C] /[I2] molar ratio of 12. The solution is stirred under nitrogen atmosphere. The procedure is same as for the above examples.
[0049] 0.0125 g (5 %w/w) of DBSA is added to 0.25 g of latex (DRC - 53.8 %). 0.025 g (10% w/w) of C60 in toluene is stirred with the latex solution for 5 hours. The I2 doping reaction is carried out by adding iodine- toluene solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere. The procedure is same as for the above examples. The results are comparable to that of example [0039].
[0050] 0.0125 g (5% w/w) of DBSA is added to 0.25 g of latex (DRC = 53.8 %). 0.0375 g (15% w/w) of C60 in toluene is stirred with the latex solution for 5 hours. The I2 doping reaction is carried out by adding iodine- toluene solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere as said in the above procedure and the results are comparable to [0040]
[0051]: 0.0125 g (5 %w/w) of DBSA is added to 0.25 g of latex (DRC = 50 %). 0.025 g (10% w/w) of Ceo in toluene is stirred with the latex solution for 5 hours. The I2 doping reaction is carried out by adding iodine-toluene solution (0.00623 g/ml) at a[C=C1]/[I2]

molar ratio of 8. The solution is stirred under nitrogen atmosphere. The procedure is same as for the above examples. The results are comparable to that of example [0048].
[0052] 0.0125 g (5 %w/w) of DBSA is added to 0.25 g of latex (DRC -= 55 %). 0.025 g (10% w/w) of C60 in toluene is stirred with the latex solution for 5 hours .the 1: doping reaction is carried out by adding iodine- toluene solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere. The procedure is same as for the above examples.
[0053] 0.25 g of latex (DRC = 53.8%) is stabilized by adding 0.005 g (2% w/w) of DBSA. The latex solution remains as a colloidal solution. 0.0125 g (5% w/w) of CGO in toluene is stirred with the latex solution for 5 hours. Then the I2 doping reaction is carried out by adding iodine- toluene solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere at a temeparture of 50^ C. The progress of the doping reaction can be inferred by the color change from purple- dark brown and from conductivity measurements. Thin films spin coated on glass substrates at different time intervals of 24, 48, 72, 96 and 240 h and dried under dynamic vacuum are used for conductivity studies.
[0054] Fabrication of a bulk heterojunction plastic solar cell.
[0055] The conjugation reaction in solution was carried by dissolving a 0.25 g (DRC = 53.8%) of latex stabilized by 0.005 g (2% w/w) of starch. 0.025g (10% w/w) of C60 -cyclohexane solution is added and stirred for 5 hours. Then the I2 doping reaction is carried out by adding iodine- cyclohexane solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere. The reaction was characterized by the respective color changes with increase in doping time. Thin film of the doped solution was casted on the ITO coated glass substrate by spin coating technique and were dried under vacuum. The metallic electrode Indium (In) was then deposited on the top of latex film through vacuum evaporation technique. The active area of the device was about 0.5 cm . The electrical conductivity measurements and the J-V characteristics were measured using Keithley electrometer model 6514 and a stabilized power supply.

Thus a PV device was fabricated using interpenetrating networks of intrinsically conducting natural rubber latex prevulcanised by gamma radiation -C60 composite films.
[0056] The conjugation reaction in solution was carried by dissolving a 0.25 g (DRC = 53.8%) of latex stabilized by 0.005 g (2% w/w) of DBSA. 0.025g (10% w/w) of C6o -cyclohexane solution is added and stirred for 5 hours. Then the I2 doping reaction is carried out by adding iodine- cyclohexane solution (0.00623 g/ml) at a [C^^C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere at temperature of 20 C.The reaction was characterized by the respective color changes with increase in doping time. Thin film of the doped solution was casted on the ITO coated glass substrate by spin coating technique and were dried under vacuum. The metallic electrode Indium (In) was then deposited on the top of latex film through vacuum evaporation technique. The active area of the device was about 0.5 cm . The electrical conductivity measurements and the J-V characteristics were measured using Keithley electrometer model 6514 and a stabilized power supply. Thus a PV device was fabricated using interpenetrating networks of intrinsically conducting natural rubber latex prevulcanised by gamma radiation -C60 composite films.
[0057] The same procedure is repeated by using Al electrode. The solution is prepared using 0.25 g (DRC = 53.8 %) of latex stabilized by 0.005 g (2% w/w) of DBSA 0.025g (10% w/w) of C60 - cyclohexane solution is added and stirred for 5 hours. Then the I2 doping reaction is carried out by adding iodine- cyclohexane solution (0.00623 g/ml) at a [C=C] /[I2] molar ratio of 8. The solution is stirred under nitrogen atmosphere at temperature of 20oC.Thin film of the doped solution is casted on the ITO coated glass substrate by spin coating technique and are dried under vacuum. The metallic electrode Aluminium (Al) is then deposited on the top of latex film through vacuum evaporation technique. The results are comparable to [0056].



We claim:
1. A process for preparing bulk heterojunctions of intrinsically conducting 1,4 -Polyisoprene (natural rubber) and C60 (fullerene), comprising (aO pre vulcanization of natural rubber latex by gamma irradiation and stabilizing the latex by adding sterric stabilizers, starch and / or Do-decylbenzenesulfonic acid (DBSA), followed by (b) blending the latex dispersion with fullerene (C60) -toluene or fullerene- cyclohexane solution at different weight percentages ranging from 5 - 15 % w/w and (c) doping the resulting composite by a adding a dopant, the dopant being iodine and / or antimony pentachloride and /or tin tetra chloride, which comprises of iodine in toluene or cyclohexane, stirring occasionally the solution under nitrogen atmosphere at a temperature range of 20o to 50o C, for time intervals ranging from 24 hrs to 240 hrs, followed by (c) spin coating the said doped solution on to Indium Tin Oxide (ITO) coated quartz and glass substrates, and drying under dynamic vacuum of 10-2 Torr to obtain thin films, on which Aluminum or Cadmium contacts is vacuum evaporated to form plastic solar cells.
2. A process as claimed in claim 1 wherein the said step of iodine doping reaction consists of adding Iodine - cyclohexane and / or iodine - Toluene solution at a molar ratio, [C=C] / [I2] = 8 and 12.
3. A process as claimed in claim 1 wherein the DRC of pre-vulcanized rubber latex is 53.8%, 50% and 55%.
4. A process as claimed in claim 1 wherein the steps of stabilization consists in adding to the prevulcanised latex, 2 to 5 % parts of starch and / or 2 to 5 % or parts of DBS A.

5. A process as claimed in claim 1 wherein stirring of the said solution with
fullerene (C60) -toluene or fullerene -cyclohexane solution at different weight
percentages of 5,10 and 15%
6. A process as claimed in claim 1 wherein the step of doping reaction consist in
stirring occasionally the reaction mixture of stabilized ,pre vulcanized 1,4-
polyisoprene latex at temperatures ranging from 20oCc to 50oC for a period of 24
to 240 hrs
7. A process as claimed in claim 1 for fabricating plastic solar cells wherein the
intrinsically conducting pre vulcanized natural rubber latex "C60 blend is spin
coated on to an ITO coated quartz substrate to get said blend's thin films of
thickness in the range of 50 to 100 nanometers ,with indium(In ) or aluminum
(Al) deposited on the top of the blend film through vacuum evaporation to act as
the positive electrode and the ITO film on quartz itself acting as the negative
electrode.


Documents:

791-che-2003-abstract.pdf

791-che-2003-claims duplicate.pdf

791-che-2003-claims original.pdf

791-che-2003-correspondnece-others.pdf

791-che-2003-correspondnece-po.pdf

791-che-2003-description(complete) duplicate.pdf

791-che-2003-description(complete) original.pdf

791-che-2003-form 1.pdf

791-che-2003-form 19.pdf


Patent Number 200785
Indian Patent Application Number 791/CHE/2003
PG Journal Number 8/2007
Publication Date 23-Feb-2007
Grant Date 02-Jun-2006
Date of Filing 29-Sep-2003
Name of Patentee DR. PADMANABHAN PREDEEP
Applicant Address PADMA VILAS, KALLUMALA P.O KERALA 690 110
Inventors:
# Inventor's Name Inventor's Address
1 DR. PADMANABHAN PREDEEP PADMA VILAS, KALLUMALA P.O KERALA 690 110
PCT International Classification Number H01B001/20
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA