Scientists at Nanyang Technological University in Singapore (NTU) have developed a next-generation sunlight to electricity solar cell material which can also emit light.

Perovskite Solar Cell Material Emits Light in the Lab.  Click image for the largest view.

Perovskite Solar Cell Material Emits Light in the Lab. Click image for the largest view.

The solar cell is built from Perovskite, a promising material (also see this link) that could hold the key to creating high-efficiency, inexpensive solar cells. The new cells not only glow when electricity passes through them, but they can also be customized to emit different colors.

Perovskite in One of its Natural Mineral States.  Click image for the largest view.

Perovskite in One of its Natural Mineral States. Click image for the largest view.

It instantly suggests self powered street lights, security lights and a shopping mall facade could be storing solar energy in the day and transforming into a light display for advertisements that glows at night.  There are a lot of possibilities.

The discovery, published in the journal Nature Materials, was discovered almost by chance when NTU physicist Sum Tze Chien, asked his postdoctoral researcher Xing Guichuan to shine a laser on the new hybrid Perovskite solar cell material they are developing.

Assistant Professor Sum said to the team’s surprise, the new Perovskite solar cell glowed brightly when a laser beam was shone on it. This is a significant finding as most solar cell materials are good at absorbing light but are generally not expected to generate light. In fact, this highly luminescent new Perovskite material is also very suitable for making lasers.

“What we have discovered is that because it is a high quality material, and very durable under light exposure, it can capture light particles and convert them to electricity, or vice versa,” said Asst Prof Sum, a Singaporean scientist at NTU’s School of Physical and Mathematical Sciences (SPMS).  “By tuning the composition of the material, we can make it emit a wide range of colors, which also makes it suitable as a light emitting device, such as flat screen displays.”

His research partner, Assistant Professor Nripan Mathews from the School of Materials Science and Engineering (MSE) and the Energy Research Institute @ NTU (ERI@N), said this newly discovered property is expected to enable the industry to feasibly adopt the material for use into existing technology.  “What we have now is a solar cell material that can be made semi-translucent. It can be used as tinted glass to replace current windows, yet it is able to generate electricity from sunlight,” he said.

“The fact that it can also emit light makes it useful as light decorations or displays for the facades of shopping malls and offices,” said Dr Mathews, who is also the Singapore R&D Director of the Singapore-Berkeley Research Initiative for Sustainable Energy (SinBeRISE) NRF CREATE program. “Such a versatile yet low-cost material would be a boon for green buildings. Since we are already working on the scaling up of these materials for large-scale solar cells, it is pretty straightforward to modify the procedures to fabricate light emitting devices as well. More significantly, the ability of this material to lase, has implications for on-chip electronic devices that source, detect and control light,” he added.

The NTU breakthrough has already won praise from experts. Professor Ramamoorthy Ramesh, the Purnendu Chatterjee Endowed Chair in Energy Technologies professor at the University of California, Berkeley in the United States said: “This work from the NTU SinBeRISE team clearly shows the promise of such new materials in a broad range of applications, including solar cells and now for lasing. It also shows the power of interdisciplinary, basic science in making fundamental discoveries that will impact in a broad sense.”

Professor Ramesh, an award-winning scientist highly regarded worldwide by both academia and industry, has over two decades of experience leading world-class research in the areas of electronics and solar materials.

In an interesting aside, the inner workings of the new NTU material designed as a solar cell were published in the world’s top scientific journal, Science, in October last year by the NTU research group.

The advanced material, which is currently patent pending, is five times cheaper than current silicon-based solar cells. This is due to its easy solution-based manufacturing process, which works by combining two or more chemicals at room temperature.

The NTU team, consisting of eight scientists and researchers, has been working on this Perovskite research project since early 2013. The project was funded by NTU and the National Research Foundation (NRF) Prime Minister’s Office, Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) program.

No word on the efficiency, but a 5 fold reduction in cost is going to have an effect, a not so hopeful one for the silicon based cell producers.  Its really disruptive technology.  But if all the world’s street lights, security lights and nighttime advertising went self powered the impact would be very substantial.  Imagine the power saved on the Las Vegas Strip or New York or Tokyo.

Impressive, indeed.


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