19 Oct Organic Solar Cell Breakthrough Offers Portable Charging for Electronics
Researchers and corporations around the globe continue to invest resources in research and development in the area of solar cells composed of organic or carbon-based semiconductors. Recent developments in Organic Photovoltaics or OPV, referred to in the industry as “third generation photovoltaics,” have a significant impact for portable, low power electronic devices and other areas.
Consumers may soon have the ability to charge their cell phones, laptops, or tablets with an inexpensive, credit card size solar charger integrated with the battery, even while using devices under low light conditions on the interior or exterior.
Scientists from the University of Warwick and Molecular Solar (a spin-off from the university) have created an organic solar cell, which has an open circuit voltage with a maximum power output greater than 7 volts (V).
A standard lithium-ion battery used to power cameras, cell phones, e-book readers, and other portable devices require 4.2 V of power.
New OPV Technology
Silicon-based semiconductors absorb light from the sun and charge transport electrons, which produce electricity. Traditional semiconductor technology requires manufacturers to stack multiple individual solar cells in a series, which increases electrical output.
The new OPV solar cell technology relies on a high congregation of tiny molecules composed of various by-products of organic pigments called phthalocyanines, said the inventor Dr. Ross Hatton.
It uses a thermal evaporation deposition process to put down four stacks or junctions. The device has a total thickness of 100–150 nanometers (nm). In addition, scientists say that solar modules created from these cells “perform well” under a variety of low light and shading settings.
Moreover, a single cell can deliver high voltage to small electronics, which previously required multiple cells.
Pros of Organic Photovoltaic
One of the main disadvantages to organics has been the power conversion efficiency. Currently, OPV have an efficiency of about 10%. In June, Sharp achieved a new solar cell efficiency record of 43.5% for crystalline silicon-based cells. In addition, OPV exhibits more sensitivity to temperature changes and oxidation, which decrease the material’s performance.
Nonetheless, organic solar cells offer manufacturers some distinct advantages:
- Lightweight and inexpensive to fabricate.
- Compatible with solution processes, such as paints or inks, which makes it suitable for coverage over large substrates, including fabrics and films.
- Manufactured at low annealing temperatures, which reduces costs and minimizes the environmental impact.
Fabricating organic solar cells at low temperatures also allows manufacturers the flexibility to choose from a range of substrates for organic devices, such as glass, transparent plastics, or a rooftop.
Current OPV research does not focus on developing organic solar cells that vie with silicon-based cells. Instead, cheap, easy to fabricate OPV solar cells have more practical applications in the areas of packaging, clothing, laptops, cell phones, and flexible screens.
As the efficiency of organics improves, Hatton believes the new breakthrough could be used on the rooftop or electric or hybrid vehicles. OPV technology may also have a significant impact on improving the photovoltaic conversion of the sun’s radiation.
The study is published in Advanced Energy Materials, October 2012.