Organic solar cells: What you need to know

Scientists are always looking for ways to make solar as efficient, accessible, and aesthetically pleasing as possible. Some of the most exciting research and development taking place in the industry today revolves around constructing thin, flexible solar options using organic solar cells.

Traditional crystalline solar cells are typically made of silicon. An organic solar cell uses carbon-based materials and organic electronics instead of silicon as a semiconductor to produce electricity from the sun. Organic cells are also sometimes referred to as "plastic solar cells" or "polymer solar cells."

One of the biggest differences between silicon photovoltaics and organic photovoltaics (OPV) is in their physical structure – organic cells are made with compounds that are typically dissolved in ink and printed onto thin plastics, which means that OPVs can be flexible and incorporated into more places or structures than crystalline photovoltaics. They can even be used to create solar power windows.

While organic photovoltaics are an exciting new technology, there's a long way to go before they can match the efficiencies already reached in silicon-based solar cells. However, given the wide range of potential applications for OPVs, it might not be long before they are a commonly used technology for generating solar energy. Additionally, organic cells are cheap to produce and physically versatile, meaning once performance can be refined, organic solar products may be able to compete with traditional crystalline cells.

Just like monocrystalline and polycrystalline silicon solar cells, organic solar cells generate electricity through the photovoltaic effect. A photovoltaic cell turns sunlight into usable electricity in three simplified steps:

1. Light is absorbed and knocks electrons loose from a semiconducting material

2. Loose electrons flow and create an electrical current

3. The current is captured and transferred to wires

In an organic solar cell, the photovoltaic process is the same, but carbon-based compounds are used instead of silicon as the semiconducting material.

Organic solar cell structure

Overall, organic cells are structured very similarly to crystalline silicon solar cells. The most notable difference between the two cell types is the semiconducting layer; instead of crystalline silicon, organic cells use carbon-based compounds (organic molecules) that are printed in an extremely thin layer onto a plastic backing.

Structure of an organic solar cell. Source: energy.gov

How do organic cells and crystalline silicon cells compare? We'll take a look at three main factors that solar shoppers might consider below: efficiency, materials, and pricing.

Efficiency

A solar cell's efficiency measures what percentage of incoming sunlight that hits the solar cell is converted to electricity. According to the Department of Energy (DOE), organic solar cells have exhibited efficiencies topping out near 11 percent (though some recent experiments have pushed that number several percentage points higher in controlled situations). The most efficient crystalline silicon solar panels available today have efficiencies upwards of 22 percent. OPVs still have a way to go before they can compete with silicon-based solar cells in terms of efficiency alone.

Materials

As mentioned above, the major difference between silicon solar cells and organic solar cells is the semiconducting material used. Silicon solar cells use crystalline silicon, while organic cells use carbon-based organic compounds applied in a thin layer to a synthetic backing. Because organic cells are made using an ink-based application and can exhibit transparentness, they usually result in a flexible solar panel that can be installed in more unique ways than traditional solar panels (such as on walls or as parts of windows).

Pricing

Solar panels made with organic cells are not commercially available, so a price comparison to silicon-based products is difficult. However, the price of traditional solar panels has fallen each year for the past decade, and solar installations are becoming more and more affordable with technological and production improvements.

One of the drawbacks of organic cell technology has traditionally been the lower environmental tolerance of organic products - moisture, oxygen exposure, and sunlight all have a more pronounced negative effect on organics as compared to crystalline cells. However, a 2019 study by a global team of engineers surfaced a potential solution to these degradation issues. The fix? Removing a certain molecule (called Phenyl-C61-butyric acid methyl ester, or PCBM) from the topmost layer of organic cells. The change results in reduced damage potential from oxygen and water. As more breakthroughs such as this are found, tested, and implemented in real products, expect organic photovoltaic technology to compete more and more with traditional crystalline technology.

According to the DOE, current research is focusing on increasing the efficiency and lifetime of organic solar cells. Three major universities are conducting this research, including the University of Florida, Princeton University, and the University of Michigan.

Organic solar cells are an exciting and promising technology that, down the line, will increase the types of spaces available for solar generation. For now, they are still being tested and researched and therefore are not available to purchase for solar panel installation.

If you're interested in solar energy for your property, many top solar panel manufacturers offer high-efficiency products that effectively convert sunlight to electricity. Check out your options for a solar installation today by visiting the EnergySage Marketplace, where you can compare qualified, local installers side by side and determine the best solar option for you.