Silicon solar cells have been around for several decades, but they’ve never been able to match the efficiency of their more traditional counterparts (i.e. conventional Si). That is, until now.
Silicon solar cells work on the same basic principles as most solar cells: they absorb sunlight and convert it into electrical energy. But how they do this is extremely different from conventional Si cells. Let’s take a closer look.
The Evolution Of Silica
While silicon was (and still is) the undisputed king of the semiconductor world, its dominance was not absolute. In fact, there were numerous other semiconductors that could be used to create more powerful and efficient solar cells. One of these more modern materials is silica.
Silica, or silicon dioxide, has been around for a very long time. It was first produced in 1821, and it has never been successfully used to create solar cells before now. (In fact, it was only in 2018 that scientists demonstrated that silica was viable for solar cell applications).
This is most probably due to the high quality of conventional Si and its relative abundance. But in 2019, all of that changed, as silica solar cells finally demonstrated their enormous potential and the world now knows more about them.
Why Does Silica Matter?
If we compare the electronic properties of silica to conventional Si, we can see that they are more favorable towards solar energy conversion. As a result, silica solar cells are able to absorb more sunlight per unit area than conventional Si cells, and this leads to better efficiency.
Silica also has a higher band gap (than Si), which means that it is more resistant to heat. This makes it ideal for cooling down PV modules or for use in satellites or spacecrafts where thermal management is critical.
To summarize, silica is the ultimate “modern” replacement for silicon when it comes to solar cell manufacture. And now that we know how great it is, we will see more and more scientists and researchers investigating its use in creating efficient and robust photoelectric devices.
How Do Silica Solar Cells Work?
Well, first, let’s get the basics out of the way. Just as with regular silicon, the performance of silica solar cells depends on several factors, including the level of doping and the size of the crystals.
As far as the size of the crystals are concerned, the general rule of thumb is that the smaller the crystal size, the more defects you will have (which, in turn, will affect the efficiency of the cell). For this reason, it is preferable to use larger crystals (i.e. >100 µm).
On the other hand, the level of doping has a direct impact on the efficiency of the device. With more and more people wanting to go green and adopt eco-friendly practices, scientists have been trying harder and harder to find substitutes for scarce resources (i.e. silicon). This has led to higher and higher doping levels, which, in turn, has increased the efficiency of silica solar cells. (As a result, these days it is very common to find devices that have a doping level greater than 10^20 cm^3).
This is probably why most silicon solar cells still use the familiar p-n junction. What is a p-n junction? It is simply a combination of a p-type material (i.e. silicon doped with boron) and an n-type material (i.e. silicon doped with phosphorus or arsenic). The p-n junction defines the boundary between two regions: a p-type region and an n-type region. While both sides of the junction are doped, the n-type side will always be more favored in terms of electronic properties.
What Are The Applications For Silica Solar Cells?
Silica solar cells were initially created as a replacement for silicon in photovoltaic devices, and that is still their primary use case. However, in 2019, a number of scientists and entrepreneurs decided to pursue a different application for silica. (As a result, many different material combinations were tested and a number of applications were eventually discovered).
To start with, silica solar cells were put to great use in creating more efficient water-splitting devices. In a nutshell, a water-splitting device is a device that is able to split water into its component parts, namely, hydrogen (H~2~) and oxygen (O~2~). This is something that we all need and use every day, and it is an essential component for future clean energy technologies.
Splitting water is not easy. You need materials that are able to withstand a strong oxidation while also having acceptable electronic properties. Thanks to silica solar cells, this has become much easier to accomplish. As a result, we are now seeing a rise in the commercialization of these devices, with many startups already selling them as a kit for DIYers who want to build their own.
In addition to water splitting, silica solar cells were also used to create sensors that are able to detect various contaminants, such as ozone and nitrogen oxides (NOX). These sensors are extremely important for air quality monitoring and they can also be used to determine the concentration of particles in ambient air.
The Future Of Silica
When it comes to the future of silica, there are several exciting possibilities. First of all, it is an excellent replacement for silicon in photovoltaic devices. In addition, silica is also becoming vital for other applications that we have yet to discover. (And believe it or not, there are already several applications for silica).
On the other hand, there are also a few practical issues that need to be addressed. For example, while it is great that silica solar cells are more efficient than regular silicon cells, they still can’t match their conventional counterparts when it comes to stability and durability. This is most probably due to the high-doping levels required to increase their efficiency (which, in turn, creates more defects). Nevertheless, with the right material engineering, this is something that can be easily fixed. (And that is what is motivating most of the research and development in this area).
In conclusion, silica is a wonderful semiconductor with the potential to completely replace silicon in numerous applications. Not only does it have a great advantage from a cost standpoint, but it also has superior properties regarding stability and durability compared to other materials.