The Clean Energy Demand
The development and industrialization of countries such as China and India is expected to more than double the global energy demand, currently 13TW annually, by 2050. One of the biggest challenges of the near future is to meet this rapidly growing energy demand with clean energy. Greenhouse gas emissions produced by coal, oil, and natural gas contribute to climate changes that are becoming a major concern. The surface temperature of the Atlantic Ocean is higher than it has been in at least a millennium, increasing the likelihood and strength of tropical storms, an increased melting of arctic ice caps, and a higher global surface temperature. It has been predicted that stabilization of atmospheric greenhouse-gas concentrations at a level that would prevent dangerous anthropogenic climate interference with the climate would require 10 TW or carbon-emission-free power by 2050.
To meet this 10 TW challenge, three major options are at our disposal, carbon neutral energy (fossil fuel use in conjunction with carbon capture and sequestration), nuclear power, and renewable energy. To produce 10 TW of carbon neutral energy using fossil fuels 25 billion metric tons of CO2 would need to be sequestered annually (12500km3 or about the volume of Lake Superior!). Using nuclear power to produce 10 TW of clean energy by 2050 would require the construction of a new 1GW nuclear plant somewhere on earth every day until 2050. For these reasons, renewable energy sources promise to be a major part of whatever strategy is taken to meet this 10 TW challenge.
Many different types of renewable energy sources will likely contribute to our future energy production, but each source can only extract a finite amount of power. Hydroelectric resources account for only 0.5 TW possible energy production, capturing energy from all tides and oceans only 2 TW, implementing geothermal energy over all land area, 12 TW, all globally extractable wind power, 2-4 TW, and the solar energy striking the earth, 120,000 TW. While all of these options will likely contribute, only solar energy stands out as the most viable choice to meet our future energy demand. Despite this vast resource, solar energy production remains less than 0.01% of current energy production.
Quantum Dot Solar Cells
Using quantum dot and dye-sensitized solar cells, the color of the solar cell can be tuned to any color of the rainbow.
In an effort to make solar technology economically viable, nanomaterials have emerged as new building blocks for the next generation of solar technology. Semiconductor quantum dots are of specific interest for use in Quantum Dost Sensitized Solar Cells (QDSCs) because of their unique properties. Their size quantization allows one to tune the visible response and vary band offsets to modulate the vectorial charge transfer across different sized particles, they exhibit large intrinsic dipole moments, and open up new possibilities for hot electron capture and multiple exciton generation.
Three configurations, solid state heterojunction, polymer-semiconductor hybrid, and liquid junction quantum dot solar cells, have emerged as viable candidates (Below) for this type of solar cell. All of these types of cells are based on the charge separation at the interface between and excited short bandgap semiconductor and a large bandgap semiconductor or polymer. In the Kamat Lab we seek to use our knowledge of the fundamental science behind light energy conversion to increase the efficiencies and the understanding of the processes involved in all of these types of QDSCs.
Solar cells architectures with semiconductor nanocrystals: (A) semiconductor heterojunction (B) polymer-semiconductor hybrid solar cells (C) liquid junction semiconductor sensitized solar cells.
- Solar Energy - Beyond the Hype - Webinar by Dr. Prashant Kamat on the clean energy challenge and solar energy.
- Build A Dye Solar Cell - Learn how to build a simple dye-sensitized solar cell
- A Delicious Solar Cell - A solar cell made from Doughnuts and Tea by former group member Blake Farrow (Youtube video)
- Measuring Photoelectrochemical Performance - A webinar on the physics and electrochemistry involved in appropriately measuring QDSCs.
Meeting the Clean Energy Demand: Nanostructure Architectures for Solar Energy Conversion. Kamat, P. V. J. Phys. Chem. C 2007, 111, 2834-2860. (Feature Article in February 22 2007 issue) NDRL 4697
Quantum Dot Solar Cells. Semiconductor Nanocrystals as Light Harvestors - Centennial Feature Article Kamat, P. V. J. Phys. Chem. B 2008, 113, 18737-18753 . NDRL 4770
Boosting the Efficiency of Quantum Dot Sensitized Solar Cells Through Modulation of Interfacial Charge Transfer. Kamat, P. V. Acc. Chem. Res. 2012, submitted.
Our Research Focus
- Use an understanding of interfacial charge transfer processes in QDSCs to improve efficiencies
- Extend the light absorption of QDSCs further into the infrared portion of the solar spectrum to harvest a greater portion of the incident solar radiation
- Elucidate the role of conducting scaffolds, such as graphene, and their incorporation into photovoltaics as electronic conductors
- Manipulation of the doping of semiconductor nanocrystals using optically active transition metals to utilize long-lived charge carriers
- Develop efficient QDSCs using simple, scalable fabrication techniques
The solar paint developed in the Kamat Lab
- Demonstrated electron and energy transfer in CdSe linked to TiO2 with a near-IR absorbing squarine dye, providing new opportunities for efficient light harvesting
- Separated the effects of nanoparticles plasmonics versus electronic charging in DSSCs
- Improved charge transport in QDSCs by employing a graphene oxide scaffold to act as an electron shuttle
- Sychronized energy and electron transfer by linking CdSe nanoparticles to TiO2 using a light harvesting squarine dye
- Developed a solar paint with higher than 1% efficiency that can be applied to any conductive surface via a simple one step process
- Boosted the efficiency of liquid junction quantum dot solar cells above 5% using manganese doping
- Demonstrated the feasibility of a pan-chromatic hybrid-sensitized solar cell using quantum dots and a NIR organic dye
Select Recent Publications
427. Know Thy Nano Neighbor. Plasmonic versus Electron Charging Effects of Metal Nanoparticles in Dye Sensitized Solar Cells. Choi, H.; Chen, W. T.; Kamat, P. V. ACS Nano 2012, 6 (5), 4418–4427.
424. Fortification of CdSe Quantum Dots with Graphene Oxide. Excited State Interactions and Light Energy Conversion. Lightcap, I. V.; Kamat, P. V. J. Am. Chem. Soc., 2012, 134 (16), 7109–7116.
423. Synchronized energy and electron transfer processes in covalently linked CdSe-squaraine dye-TiO2 light harvesting assembly. Choi, H.; Santra, P. K.; Kamat, P. V. ACS Nano 2012, 6 (6), 5718–5726.
422. Boosting the Efficiency of Quantum Dot Sensitized Solar Cells Through Modulation of Interfacial Charge Transfer. Kamat, P. V. Acc. Chem. Res. 2012, ASAP.
420. Mn-Doped Quantum Dot Sensitized Solar Cells. A Strategy to Boost Efficiency over 5% Santra, P. K.; Kamat, P. V. J. Am. Chem. Soc. 2012, 134 (5), 2508–2511.
418. Sun-believable Solar Paint. A Transformative One-Step Approach for Designing Nanocrystalline Solar Cells Genovese, M.; Lightcap, I. V.; Kamat, P. V. ACS Nano 2012, 6 (1), 865–872.
417. Supersensitization of CdS Quantum Dots with NIR Organic Dye: Towards the Design of Panchromatic Hybrid-Sensitized Solar Cells Choi, H.; Nicolaescu, R.; Paek, S.; Ko, J.; Kamat, P. V. ACS Nano 2011, 5, 9238–9245.
416. Cu2S -Reduced Graphene Oxide Composite for High Efficiency Quantum Dot Solar Cells . Overcoming the Redox Limitations of S2-/Sn2- at the Counter Electrode Radich, J. G.; Dwyer, R.; Kamat, P. V. J. Phys. Chem. Lett. 2011, 2, 2453–2460.
409. Understanding the Role of the Sulfide Redox Couple (S2-/Sn2-) in Quantum Dot Sensitized Solar Cells Chakrapani, V.; Baker, D.; Kamat, P. V. J. Am. Chem. Soc. 2011, 133, 9607-9615.
407. Graphene-based Composites for Electrochemical Energy Storage Radich, J. G.; McGinn, P. J.; Kamat, P. V. Interface 2011, Spring Issue, 63-66.
372. Quantum Dot Solar Cells. Semiconductor Nanocrystals as Light Harvestors - Centennial Feature Article Kamat, P. V. J. Phys. Chem. B 2008, 113, 18737-18753 . NDRL 4770
365. Quantum Dot Solar Cells. Tuning Photoresponse through Size and Shape Control of CdSe-TiO2 Architecture Kongkanand, A.; Tvrdy, K.; Takechi, K.; Kuno, M. K.; Kamat, P. V. J. Am. Chem. Soc. 2008, 130 4007 - 4015. NDRL 4752
351. Meeting the Clean Energy Demand: Nanostructure Architectures for Solar Energy Conversion. Kamat, P. V. J. Phys. Chem. C 2007, 111, 2834-2860. (Feature Article in February 22 2007 issue) NDRL 4697