SolarPowerNerd
Solar cells aren’t all built from the same stuff. The material inside each cell determines how efficient, durable, and affordable your panels will be.
Here’s a breakdown of every major solar cell material on the market today and what’s coming next.
What Is a Basic Solar Cell?
When we think about solar power, we usually picture panels on rooftops or sprawling solar farms generating electricity for the grid. But what’s actually inside those panels?
Thin slices of silicon with doping materials applied to the top and bottom make one side an n-type and one side a p-type semiconductor. An in-between material with just enough electrons in its outer shell separates the two layers.
The n-type material has an available electron in its outer shell, and the p-type has one less. When solar radiation hits the surface, it excites electrons and causes them to move.
If the surface is white, it reflects the light and not much happens. But if it’s black, it absorbs the full spectrum and gets hot, though that alone doesn’t produce electricity.
When the material is a semiconductor where one side has excess electrons and another side has few, the electrons want to move toward the deficit. Connect a wire from the positive side back to the negative side, and the circuit is complete.
The sun keeps pushing electrons through the circuit like a pump pushes water through a pipe.
The Evolution of Solar Cell Materials
Silicon has been used to make photovoltaic cells (PV) since Bell Labs patented the first solar cell in 1954. The actual discovery of the photovoltaic effect goes back much further to French physicist Edmond Becquerel, who found it in 1839.
In 1873, Willoughby Smith discovered that selenium could function as a photoconductor. Later, Williams Adams and Richard Day proved that a solid material could create the photovoltaic effect and generate electricity without heat or moving parts.
Then in 1883, Charles Fritz created the first working selenium solar cell. Selenium cells weren’t very efficient, and it took Albert Einstein’s 1905 paper to explain how the photovoltaic effect actually worked.
Bell Labs finally found solar cell materials that worked well enough to be useful in 1954. Silicon solar cells became the standard for panel production.
Still, silicon isn’t perfect for every application. It’s fragile, heavy, bulky, expensive, and needs large areas to deploy.
What Are the Different Solar Cell Materials Used in Creating Solar Panels?
Currently, there are two types of crystalline silicon cells: monocrystalline and polycrystalline cells.
The first high-production solar panels were monocrystalline solar cells. Monocrystalline refers to one single (and huge) silicon crystal cut into thin slices.
The silicon is processed until it’s pure to within one part per billion. The process generally includes heating and slowly cooling it to vaporize and expel the contaminants.
Heating pure silicon to just above the melting point, a seed rod is lowered into the molten silicon and slowly rotated while extracted. The Southwest Center for Microsystems Education (SCME) provided a video that demonstrates the creation of a single silicon crystal boule (ingot), the Crystal Silicon Ingot Formation.
Watch this 4-minute video for more detail about the Silicon Wafer Production from www.microchemicals.eu.
Doping material is added to each side of the wafer to make one side n-type and the other p-type. Painting a series of thin silver strips to the n-type side and adding an aluminum conductive sheet or substrate to the p-type side completes the cell.
A glass or other transparent material covers the sun-side of the cells (n-type), and cabling and connectors complete the circuit. The cells in this panel are almost black.
Monocrystalline solar panels are prevalent in the marketplace. They’re high on the scale of efficiency, but the cost is high too.
The single crystal is expensive to make and starts as round disks. The wafers need to be cut several times to make them rectangular for more effective use of the panel area.
That creates a lot of waste material and costs a lot to manufacture.
What Are Polycrystalline Solar Panels?
Making polycrystalline solar panels is similar, except the silicon is purified, then poured into large ingots and cut to size without going through as much process and without producing as much scrap.
These panels are blue, and the crystalline silicon cells formation is uniform but uses many smaller crystals. If you’d like to see the whole process, watch this 13-minute video Solar Modular Manufacturing from GP Solar.
What Are Amorphous Silicon Solar Panels?
Amorphous silicon makes the third primarily silicon-based solar panel on the market. It belongs in the class of thin-film technologies.
The thin-film solar cell can be mass-produced directly onto a sheet of plastic 1,000 feet long. The back-metal contact is applied first, followed by about six layers of solar cell materials, including amorphous silicon and semiconductor silicon making the actual cell.
Installing a top transparent conductive layer completes the cell layers. That’s essentially one substantial 1,000-foot solar cell.
The long sheets are then processed to make individual cells and built back up into various sized panels based on the need of the product. These panels have a wider variety of applications than mono and polycrystalline panels.
The manufacturing process is much simpler, so the costs are much lower. Efficiency is decreased, and life expectancy drops because products get more exposure to rugged environments.
What is Cadmium Telluride (CdTe)?
Next on the scene in thin-film technologies were cadmium telluride solar cells, introducing new materials for solar cells.
One method uses a glass substrate for the bottom layer, a transparent conductive layer, and a layer of cadmium sulfide to create the n-type semiconductor. Another layer of cadmium telluride forms the p-type layer.
The rest of the cell’s process uses the same technology as mentioned earlier.
For a great explanation of the manufacturing process, see this 4-minute video First Solar’s Modular Manufacturing Process.
Cadmium telluride solar cell efficiencies are nearly equal to polycrystalline cells, and the manufacturing cost is lower. Still, they introduce new challenges.
Cadmium is a very toxic but plentiful element. Tellurium is rare.
There are environmental concerns, but it appears there are steps in place to make the manufacturing process safe.
The solar panels typically have a shorter lifespan, and recycling both the cadmium and the telluride is essential.
What Is Copper Indium Gallium Selenide (CIGS)?
Next on the scene are Copper Indium Gallium Selenide solar cells. Referred to as CIGS solar cells, they introduce even more new materials.
Solar cell materials include a conductive layer placed on the substrate, then CIGS semiconductor material, a transparent conductive layer of cadmium sulfide (CdS), then a transparent zinc oxide (ZnO) layer, and an anti-reflective coating of magnesium fluoride (MgF2). Some applications eliminate the CdS layer for a cadmium-free finished product.
While CIGS is currently one of the most efficient thin-film solar cells on the market (22.9% efficiency in the lab), the cost of production and price to the end-user is high.
What Are Organic Photovoltaic Cells (OPVs)?
OPVs are a class of organic solar cells used in photovoltaic applications. This type of cell introduces organic polymers as solar cell materials.
That doesn’t mean little organisms live in OPV cells converting sunlight to electricity. Organic polymers are made up of chemically organic elements: carbon, hydrogen, oxygen, nitrogen, halogens, and sometimes sulfur and phosphorus.
Organic polymers make up the semiconductor between two metal electrodes (usually a transparent indium tin oxide and an alloy of aluminum-magnesium and calcium). OPVs have many uses because there are many absorbers or organic polymer semiconductors available, combined with their flexibility and relatively low cost to produce.
OPVs enable building-integrated photovoltaics that allow buildings to produce the electricity they need and provide attractive color schemes. They do experience low efficiency (11%) and a short life span compared to silicon-based panels.
A team in China produced OPVs using a tandem design method that achieved 17.3% efficiency. OPVs are beginning to look much more promising because of this.
What Is the Perovskite Solar Cell?
Results have been published for perovskite cells with lab-tested efficiencies at 23.7%, and 28% for tandem perovskite cells. Manufacturers print the solar cells using ink materials for low-cost production, and the material absorbs the complete visible spectrum of light.
Efficiencies are high, and costs are low. The perovskite semiconducting material is typically a methylammonium lead trihalide (CH3NH3PbBr3).
Manufacturers often substitute with either iodine or chlorine for bromine.
The architecture is relatively simple. Imagine a transparent n-type conductive layer coated with a perovskite material and covered by a p-type conductive layer.
See the TEDx Talks video on perovskite cells. If you’d like to dive deeper into photovoltaic technologies, take a look at these free online courses by Mark Lundstrom of Purdue.
What Are Other Solar Cell Technologies?
Other cell types don’t introduce new solar cell materials but use different ways to deploy the same kind of solar cells with higher efficiencies or lower overall costs.
Look at the Best Research-Cell Efficiencies chart published by the National Renewable Energy Laboratory (NREL) in Golden, Colorado. You can see the latest solar technologies tested in their lab.
The four-junction semiconductor device with a concentrator is highest on their chart and likely to stay there. This device is essentially a compound semiconductor.
Multiple silicon-based solar cells are combined and tuned to a range of wavelengths of light to allow better use of the full spectrum. A concentrator, which can be as simple as a magnifying glass or mirror, focuses the light on the target of the solar cell.
A cell of this type is far too expensive for most people to use on their rooftops. Still, it has made it into space technologies where efficiency is essential to mission success.
Other technologies on the horizon include solar cell fabric and tandem perovskite cells.
Frequently Asked Questions
Which material is most commonly used in solar cells?
Silicon is by far the most common material in today’s solar cells. It’s abundant, well-understood, and strikes a good balance between efficiency and durability.
Both monocrystalline and polycrystalline silicon cells dominate the residential and commercial solar panel market worldwide.
Are perovskite solar cells better than silicon?
Perovskite cells show impressive lab efficiencies up to 28% in tandem designs, and they’re cheaper to manufacture than silicon. They aren’t widely available yet because long-term durability and stability still need improvement before they can compete with silicon’s proven 25-year track record.
What makes thin-film solar cells different from crystalline panels?
Thin-film cells use much less material and can be deposited on flexible substrates like plastic. They’re lighter, cheaper to produce, and work in more applications.
The trade-off is lower efficiency and shorter lifespans compared to monocrystalline or polycrystalline silicon panels.
Can organic solar cells power a home?
Organic photovoltaic cells aren’t efficient enough yet to power a full home. Their efficiency sits around 11-17%, and they degrade faster than silicon.
They’re better suited for building-integrated applications, portable electronics, and situations where flexibility and lightweight design matter most.
Final Thoughts
Solar cell materials have come a long way since Bell Labs built the first practical silicon cell in 1954. Today, options range from traditional crystalline silicon to thin-film cadmium telluride, CIGS, organic polymers, and perovskites.
Each material brings its own balance of efficiency, cost, and durability. The right choice depends on your specific application, budget, and performance needs.
New technologies are pushing solar products into building materials, window coatings, and flexible fabrics. As research continues, the number of useful elements has expanded to cover a substantial portion of the periodic table.
