Polymer based photovoltaics for solar cells  

Posting by Rahul Gaba on 17 Jul 2008 at 21:51:32.

I'm looking for a novel polymer based coating material to be used in organic photovoltaics for a solar cell. Reason is that combined exposure to moisture and UV light reduces photovoltaics ability to convert sunlight in electricity. Therefore most polymer, or thin film, based solar cells have a service life of about 25-30 years.

Currently some technologies are being developed, such as a Photon Conversion Material (PCM) coating which converts UV light in visible light (using blue Polyfluorene). This (also plastic based) solar cell technology is perhaps promising, but seemingly adds (only) 5 years to the lifetime.

I am looking forward to you comments!

Rahul Gaba

          follow up posts
    On 19 Aug 2008 at 21:54:53 Composite Analytica posts:
    Dear Rahul:

    We will get back to you shortly with some detailed feedback, but at this moment please be informed that near the end of September 2008 there will be a workshop in London on the integrated properties (corrosion resistance, flexible mechanical properties and permeability / barrier behaviour) of high performanced electronics such as plastic based photovoltaics (PV 's) and Organic Light Emitting Diode (O LED 's). Click this news link to learn more.

    Composite Analytica
    [responses: 7]

      On 28 Aug 2008 at 23:13:03 Rahul Gaba posts:
      Thanks for your replies! I recently fabricated my first Organic Solar cell using glass substrate and nano layers of organic polymer blends. Now working on reducing the environmental effect on the cell and increasing its efficiency! Thanks,
      Rahul Gaba
      [responses: 6]
        On 21 Sep 2008 at 13:08:00 Max posts:
        Dear Rahul,

        For my thesis, I am currently working on an evaluation of different substrate materials for solar cells. Do you know whether electric current loss through plastic of polymer based substrate materials is a significant issue (probably with and without the presence of diffused moisture - i.e. some sorts of Polyamide have an equilibrium moisture uptake of 20 wt% - does this cause electric current loss)?

        I have some idea of the electric conductivity of polymers, so in essence I want to know the electric current in a polymer based solar cell of 3 to 5 Volts (at the Tin Oxide anode side)?


        p.s. the electrical conductivity of Polyamide without moisture equals 10 E-12 S/m [A/ V m].
        [responses: 4]

          On 21 Sep 2008 at 16:52:10 Rahul Gaba posts:
          Dear Max ,

          I worked only with ITO coated Glass substrate. We didn't use polymer substrate intentionally because we were working on increasing the cell efficiency and for this purpose annealing (heating at high temperature & cooling thereafter) is a very important step. Since there is a limitation of the high temperature to which polymers or plastics can be subjected to but not so with glass, so we went for glass substrate.
          Unfortunately I don't have any definite answer to your query at the moment but will revert back in case I get any info.
          From what i think:
          We use plastic/glass just a substrate, ITO is the electrode, don't you think moisture, if any , present in the plastic will vaporise when cells are annealed? also we can provide the substrate with some insulation(on the opposite side of ITO) to prevent any electric loss. are you referring to the the dielectric dissipation loss within the polymer substrate itself? can't we prevent it by using water resistant coating on the polymer substrate?
          [responses: 3]

            On 30 Sep 2008 at 19:21:31 Composite Analytica posts:
            Hi Max,

            The issue you raise is rather interesting. Here follows a short and very global calculation of the Amperes in a plastic based Solar Cell:

            -100% Sun Light ~ 1 kW/m2,
            -Polymer Based Solar Cell Efficiency ~3% = 30 W/m2
            -Voltage ~3 Volt

            As Power = V x I, then it follows that I=10 A/m2.

            I think most the conductivity of the polymer can be neglected, compared to 10 Amperes per square meter. Moreover, as a transparent substrate, more hydrophobic polymers are used. Water diffusion rate [m2/s] and total water vapour transmission rate [WVTR gram/m2 day] of candidate materials, such as polyesters: Polyethylene Terephthalate (PET), Polyethylene Naphthalate (PEN)*, a transparent Polyimide (PI) is much lower. For their electrical conductivity in humid environment or occasions where a lot of moisture is present, the article "Study of electrical properties of polymeric materials using electrochemical impedance spectroscopy" at Wiley Interscience may be of your interest.

            Composite Analytica

            *the oxygen, water vapour transmission rate of PEN is globally five times lower than PET.

            [responses: 1]

            On 23 Sep 2008 at 11:46:45 Max posts:

            Many many thanks for your reply! My primary interest is the electric conductivity of the plastic - or polymer based - substrate in real-life conditions, i.e. moisture from the atmosphere (as a result of rain or high humidity) which is capable to diffuse into any plastic material. With glass this is indeed not a potential problem. On the other hand, plastic substrates are lightweight and mechanically flexible...

            Polyamide is quite hydrophilic, so the electric conducitivity will definitely change during water exposure. How much Voltage and Electric Current (Amperes) did you obtain per square meter of cell, globally?

            Thanks again.

            Best Regards,
            [responses: 0]

    On 29 Jul 2008 at 14:11:16 Solar Shock posts:
    Rahul, I am afraid that currently I can not suggest another better material for photovoltacis. Nevertheless I am interested in this thread since polymer based solar cell materials have a wide range of interesting features, such as that they can spin from Light Emitting Diode (LED's), their flexible properties combined with low weight of plastic materials.

    Keep up the good work!

    [responses: 0]

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