The basic composition of a cell, as imagined by Professor Michael Grätzel is as follows:
A transparent conducting oxide (TCO) is deposited on a transparent substrate, glass or plastic, to make two electrodes.
On the working electrode, a thin layer (around 10 μm) of nanoparticles of a semiconductor, the titanium dioxide (TiO2), is deposited. Then, the TiO2 is sintered to create “necks” between the nanoparticles of TiO2, and allow the transport of the electrons from particle to particle to the TCO.
The electrode with the TiO2 is soaked in a dye, composed of either ruthenium or organic dyes. The molecules of dye will cover the surface of every nanoparticle. The dye is the photoactive material of the cell: it will catch the photons of the incoming light and convert them into electrons. The diffusion of those electrons through the TiO2 and the TCO creates a current. This electricity is then used to power external devices or to charge batteries.
At this stage, the dye has given an electron to the external circuit and therefore is missing it, it is “oxidised”. To be able to absorb another photon and created another free electron, it should first be “reduced”, which means that it should get a new electron. This electron is coming back from the external circuit through the counter electrode. The electrolyte, is used to transport the electrons from the counter electrode to the dye between the nanoparticles of TiO2. The cycle is now complete and will begin again with the next absorption of a photon by the dye.
G24i DSTF (Dye Sensitized Thin-Film) Characteristics
- US Department of Energy, 2015 National Solar Technology Roadmap recognizes two technologies, that have the ability to compete with nuclear and coal, DSSC and Concentrator, which have a 5x cost reduction potential.
- Excels in a wide range of light conditions at various angles; flexible, lightweight and robust.
- Outstanding energy payback, resulting in a low carbon footprint.
- DSSC Nano structured systems have the potential to go beyond the Schockley-Queisser limit of 32% efficiency.
According to Dr. Stephen Chu, Secretary of Energy, “In order for solar to displace nuclear and coal, we need a 5x cost reduction.”
Consumer Electronics and BIPV
G24i will concentrate initially on the Consumer Electronics market, manufacturing a DSSC PV solar module which can be adopted in a wide variety of applications, including a mobile phone charger for the developing world where the requirement for off grid technologies is a necessity.
In conjunction with a focus on consumer products, G24i will aggressively develop modules for indoor remote power applications, electric vehicles (EV), E-paper and Building integrated photovoltaics (BIPV).
The main advantages of G24i’s DSTF over existing PV technologies include:
- DSTF devices generates more energy in diffuse lighting conditions (both indoors and outdoors).
- Does not suffer from angular dependence of sunlight.
- DSTF can generate more power over extended periods of time than competing silicon technology.
- Efficiency of DSTF does not degrade with increased temperature.
- DSTF panels allow for form factor variation which allows for flexible, thin and lightweight modules.
- Uses inexpensive and eco-friendly nanomaterials.
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