How nanotechnology is driving the next generation of solar energy technologies. Our definitive guide to what’s happening in nanotech enabled photovoltaics.
“The nation that leads the clean energy economy will be the nation that leads the global economy.”
President Barack Obama, State of the Union address.
Nanotechnology in solar energy
Demand for solar power is rising rapidly. The need for advanced renewable energy technology has become increasingly critical as an environmentally sustainable path to world economic and societal development. It is estimated in 2009 approximately 7GW of PV solar capacity was installed at a cost of approximately $39billion, rising to $82billion in 2010. Conservative projections put worldwide annual capacity at 200 GW in 2020; others estimate as much as 300 GW in 2025. US, Asian and German governments are all pushing hard for new solar technologies and there is strong demand from private/public sectors investors in developing countries.
Cost-effective photovoltaic (PV) technologies are the key for large-scale deployment of solar cells capable of producing clean energy. Although conventional planar crystalline PV cells can provide good efficiencies, they are not viable for large-scale deployment because of relatively high costs. On the other hand, inorganic and organic thin-film semiconductor-based PV cells have low material and fabrication cost, but their large-scale performance is poor. First generation solar cells are made from bulk silicon, either single crystalline and polycrystalline silicon and make up the vast majority of the market. Second generation encompasses thin films. Third generation soar cells promise lost-cost and high-efficiencies-greater than 20% efficiencies with costs similar to second generation.
Nanomaterials are a key component of third generation solar devices, providing the material requirements to significantly, rather than incrementally, improve photovoltaic cell performance beyond that of present devices. Nanostructured materials grown with low-cost, bottom-up approaches usually have crystalline nature and, therefore, are promising candidates to achieve cost-effective PV cells. In addition, ordered nanostructures have demonstrated intriguing optical and electrical properties favouring photon broadband absorption and photocarrier collection. This suggests a potential route towards next-generation, high-efficiency PV devices.
Nanomaterials utilized in photovoltaics to address third generation approaches include:
• Semiconducting polymers and oligomers
• Conducting nanomaterials
• Dyes
• Fullerenes
• Liquid crystals
• Metal Oxides
Nanostructured materials find application in photovoltaics as:
• Nanocrystalline thin-film layers
• TiO2 nanoparticles in dye solar cells
• Fullerene derivatives as electron acceptors
• Nanolayers in stack cells
• Graphene electrodes
• Quantum dots for bandgap tuning
• Nanostructured anti-reflection layers
• Quantum wells for bandgap tuning
• Metal nanoparticle plasmonic solar cells
Efficiencies for nano-enabled solar cells are significantly less than those of conventional wafer silicon cells at present. However they are cheaper and more eco-friendly as their production demands less time, material and energy. The market is mainly being driven by start-ups who often work in collaboration with larger companies. These companies have raised over $2billion in investment in the last five years for product development. Module efficiencies for nanomaterials used in second and third generation photovoltaics range from 5-17.1% at present.
Players in nanotechnology enabled photovoltaics include:
• 1366 Technologies, Inc.
• 3G Solar
• BASF
• Bloo Solar
• First Solar
• Cyrium Technologies, Inc.
• Dyesol
• Eight19
• General Electric
• G24 Innovations Limited
• Heliatek
• Illuminex Corporation
• Konarka
• Molecular Solar
• Nanosolar
• Oxford PV
• Orion Solar
• Siena Solar Nanotech
• Solaronix SA
• Solarmer Energy
• Solexant Corporation
• Solaris Nanosciences
• SoloPower, Inc.
• Sony
• United Solar
