DSC TECHNOLOGY

The Dye Solar cell has been called the first real revolution in solar energy since the commencement of silicon solar cell work some 40 years ago. It is a new technology with performance characteristics which make it ideal for use on vertical surfaces, indoors or in shadowy conditions.

DSC are third generation photovoltaic electricity generators, based on the principle of artificial photosynthesis, utilising nanotechnology and molecular engineering. DSC solar cells are particularly suited to local energy generation for military purposes, because they are less sensitive to light variation and angle of the sun, as well as producing proportionally more power in lower light conditions.

DSC 3^rd Gen Photovoltaic (PV) technology can be realised on glass or metal substrates. The 3^rd Gen cells are produced by screen-printing – the process extendable to inexpensive roll-to-roll manufacture on flexible substrates. The high surface area of titania nano-composites results in the ability to perform in cloudy and smoky environments, not just under clear and sunny sky needed by earlier generation PV.  

It has been recognised that traditional battery based power sources do not satisfy the requirements of the modern defence theatre. Supply, cost, safety and disposal are all issues. Rapidly increasing usage of all forms of energy and, especially of electrical energy, makes battlespace energy generation and storage a crucial capability of the modern defence force.

DSC is Different to Silicon

The important features that distinguish DSC from conventional photovoltaics are as follows:

It is a photoelectrochemical cell: charge separation occurs on interface between a wide bandgap semiconductor and an electrolyte.

It is a nanoparticulate titania cell: it is not a dense film as is amorphous silicon, but a "light sponge".

It is a Dye-sensitised cell: a dye monolayer chemically absorbed on the semiconductor is a primary absorber of sunlight; free charge carriers are generated by electron injections from a dye molecule, excited by visible radiation.

The basic titania (TiO2) based DSC cell consists of a sandwich of TiO2, dye, electrolyte and catalyst between two conductive transparent electrodes. Upon illumination of the cell, charge separation occurs by electron injection from the excited state dye molecule into the conduction band of TiO2. Simply, light excites the dye, sending an electron on its way to be picked up and transmitted by the semiconducting titania to become electrical energy. The dye is then reduced by an electron transferred by the redox couple.

Simple in Design There are three main design formats for DSC products. The first is the parallel cell which requires integration of separate cells to form a module. This design has a number of materials engineering limitations, so it has not yet been commercialised. The other two designs, the Integrated Module and the Monolithic differ mainly in the design of the counter electrode. The Integrated Module Design comprises two sheets of conducting glass with the electrode deposited on one sheet and the counter-electrode deposited on the second sheet. The advantages are: Semiconductor Processing – methods of improving nanostructural characteristics of the semiconductor to provide the preferred meso pore    structure. Techniques are being developed to reduce voltage losses due to junction formation at the interfaces. Suitable for high solar radiation Optionally transparent or translucent Suitable for building integration Can be hermetically sealed for ultra long life The Monolithic Design is built up sequentially on one glass substrate. The module utilises the conductive glass as the collector for both the electrode and counter-electrode. This design has the following advantages: Lower production cost Potential for larger cells Cheaper material bill Amenable to continuous production Features of the DSC manufacturing process include: Materials used in significant quantities have the capacity to be produced cheaply in high volumes; Manufacturing processes are ‘simple’ using standard processing and assembly equipment; Embodied energy is low, i.e. the manufacture is not highly energy intensive; Manufacturing processes, being similar to thick film hybrid processes and laminated window manufacture, are amenable to automation.   Advantages of DSC Compared to other solar cells, the titania solar cell has the following advantages: Much less sensitive to angle of incidence of radiation good in refracted and reflected light. Performs over a much wider range of light conditions due to the high internal surface of titania ("light sponge") – can be designed for operation at very low light Can be designed to operate optimally over a wide range of temperatures. Much less sensitive to a partial shadowing Option for transparent modules - so can be used for day-lighting, roof lighting, displays. DSC production needs only commonly available non vacuum processing equipment, making it vastly cheaper to set up facilities. DSC has significantly lower embodied energy than all other forms of solar cell.