Organic Photovoltaics–Did Green Just Get Greener?

by Sebastian Haefele

Organic photovoltaic (OPV) definitely sounds like it could be one of the greenest renewable energies. However, the organic in the name does not mean the materials they use grow readily in nature or would be compostable. They are, in fact, the result of sophisticated chemical engineering at the molecular level.

But, this is nothing new, so what is the real excitement around OPV? This technology makes a lot of tempting promises: producing material that is flexible, lightweight and can be manufactured on a roll-to-roll basis, i.e. printed on a roll of plastic like news on paper. Or is it its ability to harvest light at low levels, unavailable to conventional silicon-based PV cells, like on windows and building facades? Windows would still be transparent and still let visible light pass through them, covering a portion of the buildings energy demand.

The flexibility of OPV offers huge areas of application. In a recent study, scientists argue that organic PV cells could help power consumer electronics. Because the color of these cells is variable, product designers have more flexibility in incorporating them into products. Nevertheless, that would be a niche application and not an application that would create a major impact in the renewables field. So, is the hype justified?

The challenges that OPV faces are pretty serious: to compete with silicon-based PV (Si-PV) researchers and developers need to increase efficiency and longevity of these cells. An OPV system that costs half as much as a Si-PV system, but only lasts half as long is still as expensive as its counterpart. Efficiency also plays an important role when it comes to quantifying the environmental impacts that occur during manufacturing of these cells. OPV has a lot of potential given they can be produced at lower temperatures than Si- PV, and lower temperatures require less energy. Studies find they currently don’t perform as well as most silicon PV, but progress in manufacturing could lead to greenhouse gas emissions per kWh that are as good as those of the environmentally friendliest Si-PV.1, 2

But what about prices? According to a study3, OPV modules could be installed at competitive prices, as long as they can muster 7% efficiency and 5 years of module lifetime. However, lifetime is also their greatest weakness and field testing has been limited, so studies based on assumptions of lifetime might miss the point. As a result, a study by the company Lux Research predicts OPV will garner only a small market niche in the future—and competition from thin-film PV, which offers similar advantages like flexibility paired with higher efficiencies.

There is still a long way to go before OPV becomes a part of the renewable energy system. OPV is unlikely to be a player in the renewable energies market soon. It holds strong promise, but has to overcome great hurdles and the competition isn’t idle. Similar technologies compete for every inch of ground and offer similar advantages. However, the technology is admittedly compelling and somewhat unpredictable given its potential for diversity in materials used. Who knows, maybe we will soon be looking at artificial trees with OPC cells for leaves, like developers in Florida envisage.4

 

Sebastian Haefele joined CRS in May 2015 as a Green-e Energy Verification Associate. He has a Master’s degree in environmental science and has expertise and interest in life-cycle assessment of products and services like renewable energies, energy storage technologies and biofuels, energy and carbon accounting for counties and energy technologies in general. He focuses on research for R&D programs regarding the energy-environment nexus, but is always curious to find out more about the field of environmental consulting and sustainability.

 

Additional Information

 

References

  1. Darling, S. B. & You, F. The case for organic photovoltaics. RSC Adv. 3, 17633–17648 (2013).
  2. Lizin, S. et al. Life cycle analyses of organic photovoltaics: a review. Energy Environ. Sci. 6, 3136 (2013).
  3. Azzopardi, B. et al. Economic assessment of solar electricity production from organic-based photovoltaic modules in a domestic environment. Energy Environ. Sci. 4, 3741–3753 (2011).
  4. Cao, W. & Xue, J. Recent progress in organic photovoltaics: device architecture and optical design. Energy Environ. Sci. 7, 2123–2144 (2014).