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Graphene has been touted for several high–tech applications but has only made commercial inroads in a few different areas so far. One of these areas is solar cells.
There is a lot of potential for graphene in solar cells, and it is an area where many of its properties can be utilized to favourable effect. Over the last few years, there have been several commercial offerings hitting the market, with the latest one this year targeting the marine sector.
The Commercial Appeal of Graphene Solar Cells
Graphene possesses a range of beneficial properties, including a high degree of flexibility and tensile strength, a high electrical conductivity and charge carrier mobility, a high thermal stability, an almost 100% optical transparency, and the ability to be doped.
Even though graphene is typically a zero–bandgap material (i.e., completely conductive), there are derivatives out there which are semi–conducting in nature Pure graphene sheets can also be doped with a range of atoms to make them semiconductor materials ― which makes them suitable for use in photovoltaic junctions.
The use of graphene, however, is not just focused on the junctions. One of the most widely used areas of graphene, and one which has the most commercial potential, is to utilize its conductive nature as a replacement for indium tin oxide in the transparent electrodes used in solar cells. Beyond this, there is also the potential for graphene to be used as a non–reflective coating to improve the light absorption of other types of solar cells.
Aside from the electrical properties exhibited by graphene, the structural properties are just as interesting from a commercial standpoint, and there are solar cells which have come to market for this reason. Solar cells that incorporate graphene tend to undergo less thermal stress during production, resulting in fewer microcracks forming in the cell compared to normal.
Once in use, the mechanical properties and stability of graphene compared to more traditional materials means that the solar cells are likely to degrade less and last for longer, offering a better cost effectiveness in the long run.
The ability for graphene to be tuned and customized, alongside its various other properties, is enabling a range of solar cells to be created at both the academic and industry level to suit many applications. The inherent thinness and flexibility of graphene is also opening the door towards more flexible, printable, and transparent solar cells.
While these more ‘exotic’ styles of solar cells are still seen more at the academic level, there are other graphene–enhanced solar cells that have already hit the market and others which are currently undergoing extensive trials.
The Commercial Adoption of Graphene Solar Cells
While there is a lot of promise, commercial development of graphene solar cells is still confined to academic labs or are not quite ready for trials, yet. There have been a few notable commercial developments over the last few years, however, which have led to graphene solar cells being used in real–world applications.
The first notable commercial development came from the longstanding Chinese company ZNShine in 2018 when they worked directly with India’s largest power generation equipment manufacturer, Bharat Heavy Electricals Limited, to tackle the issues of dust accumulating on solar cell farms in India.
In the case of ZNShine’s solar cells, the graphene is used in a coating on top of the sun–facing panel to offer improved light performance and to make the surface self–cleaning so that regular and extensive maintenance is not required in dusty environments. ZNShine has since gone on to offer many different solar cell devices to the market, all of which use the graphene coating to improve the power conversion efficiency of their solar cell technologies.
The second biggest development over the last few years was when Freevolt brought graphene solar cells to the market for residential use. The solar cell technology rights were also bought out by S2A Modular for use in their self–sustaining homes.
These solar cells utilize graphene as a transparent electrode on top of the cell, allowing the cell to not only take advantage of the excellent conductive properties that graphene possesses (improving efficiencies), but also its structural properties. Because it is integrated near the surface, it minimizes the surface degradation of the solar cell, reduces thermal and other external environmental factors from affecting the cell, and improves the usable life of the cell.
A New Approach Toward Marine Applications
Looking towards recent commercialization efforts, graphene solar cells in 2022 have been targeting the marine sector thanks to the U.K.–based company Grafmarine. These new graphene solar panels, termed the ‘NanoDeck,’ are set to be used to power ships and have been designed to be suitable for use in marine environments, where conditions are typically different (and often harsher) than residential settings.
The solar cells aim to tackle the high carbon emissions given off from the global shipping industry. Grafmarine developed the NanoDeck to be modular so that they can fit on to the surface of any ship. The NanoDeck uses graphene in the form of a composite as well as in a structural and conductive capacity because the graphene composite not only forms part of the photovoltaic technology, but also the structural properties help the solar cell withstand harsh environments at sea.
At this stage, there are currently only prototypes available, but it has been announced recently that the next phase of trials is going to be starting off the coast of Wales to test the true commercial potential and efficiency of the graphene enhanced NanoDeck, as well as how well the modular systems work with each other. The trials are currently being performed in conjunction with the Marine Energy Engineering Centre of Excellence, improving the technology readiness level of the solar panels.
While Grafmarine’s solution remains in the prototype phase, there is a lot of potential to help reduce the emissions given off by long–haul ships. Should the tests be successful, there is also talk of these modular systems being suitable for use with wind turbines, on shipping docks, and for powering hotels.
These are vastly diverse sets of commercial markets compared to other graphene solar cell technologies that have come before it ― such as those focused on solar farms or residential markets ― showing interest in graphene in varying high–tech markets is growing.
We have already seen a reasonable improvement in graphene solar cell commercialization in a relatively short time. With more investment and collaboration going into graphene products and collaboration projects, it is likely that these will not be the only commercial offerings on the market in a few years, and we may even see even more markets opening as well.