Low Cost, Efficient Solar Cell

Tuesday, October 22, 2013 @ 12:10 PM gHale


The potential of solar energy continues to fascinate researchers across the globe with its potential to become a low cost source of energy, but the sticking points always come at the efficiency and the cost point.

But that may soon change as solar panels can not only become more efficient but also a lot cheaper and affordable for everyone, according to research by Singapore-based Nanyang Technological University (NTU) scientists.

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The next generation solar cell, made from organic-inorganic hybrid perovskite materials, is about five times cheaper than current thin-film solar cells, due to a simpler solution-based manufacturing process.

Perovskite is a quality solar cell material because it can convert up to 15 percent of sunlight to electricity, close to the efficiency of the current solar cells, but scientists did not know why or how, until now.

The team of eight researchers led by Assistant Professor Sum Tze Chien and Dr. Nripan Mathews worked with NTU Visiting Professor Michael Grätzel, who found perovskite solar cell efficiency up to 15 percent.

Grätzel, who is at the Swiss Federal Institute of Technology in Lausanne (EPFL), has won multiple awards for his invention of dye-sensitized solar cells.

The high sunlight-to-electricity efficiency of perovskite solar cells places it in direct competition with thin film solar cells which are already in the market and have efficiencies close to 20 percent.

Understanding how these solar cells work, researchers are now applying that toward developing a commercial prototype of the perovskite solar cell in collaboration with Australian clean-tech firm Dyesol Limited.

The discovery of why perovskite worked so well as a solar cell material came through the use of cutting-edge equipment and in close collaboration with NTU engineers, Sum said.

“In our work, we utilize ultrafast lasers to study the perovskite materials. We tracked how fast these materials react to light in quadrillionths of a second (roughly 100 billion times faster than a camera flash),” said Sum, the photophysics expert from NTU’s School of Physical and Mathematical Sciences.

“We discovered that in these perovskite materials, the electrons generated in the material by sunlight can travel quite far. This will allow us to make thicker solar cells which absorb more light and in turn generate more electricity.”

The NTU physicist added this characteristic of perovskite is remarkable since it consists of a simple solution that normally produces low quality materials.

Mathews, a senior scientist at ERI@N, said their discovery is a great example of how investment in fundamental research and an interdisciplinary effort, can lead to advances in knowledge and breakthroughs in applied science.

“Now that we know exactly how perovskite materials behave and work, we will be able to tweak the performance of the new solar cells and improve its efficiency, hopefully reaching or even exceeding the performance of today’s thin-film solar cells,” said Mathews, who is also the Singapore R&D Director of the Singapore-Berkeley Research Initiative for Sustainable Energy NRF CREATE program.

“The excellent properties of these materials, allow us to make light weight, flexible solar cells on plastic using cheap processes without sacrificing the good sunlight conversion efficiency.”

Professor Subodh Mhaisalkar, the Executive Director of ERI@N said they are now looking into building prototype solar cell modules based on this exciting class of materials.

“Perovskite-based solar cells have the potential to reach 20 percent solar cell efficiencies and another great benefit of these materials is their amenability to yield different translucent colors, such as red, yellow or brown,” he said. “Having such colorful solar glass will create new opportunities for architectural design.”



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