Homemade DIY Project May Blast Perovskite Solar Cells Into Production
Perovskites could be the future of solar cells—if it weren't for their hard-to-detect defects. Now, a researcher's homemade machine may provide answers.
While most researchers look up to the stars for answers, one scientist recently used a DIY project at home to forge ahead in solar energy technology.
On Aug. 16, Dr. Jamie Laird, a research fellow at the Australian Research Council Centre of Excellence in Exciton Science, presented a new machine to help scientists predict the location of potential defects causing perovskite solar cells (PSC) to collapse. Perovskite solar cells, a promising alternative to silicon, are still prone to compromising flaws that, until now, have been difficult to detect.
Solar cells are meant to last over 20 years in space. Dr. Laird (pictured above) believes this new method may be an important step toward extending perovskite solar cell lifespan. Image (modified) courtesy of Exciton Science
With Dr. Laird's new laser-based testing method for PSC defects, scientists may be able to add defensive traits to PSCs to help stabilize and sustain the lifespan of these cells.
The Pros and Cons of Perovskite Over Silicon Solar Cells
Silicon has primarily been used for light harvesting in space applications and yields a significant return of reusable energy. One drawback is the thickness and heaviness of silicon-based devices, which are not practical for lightweight design requirements. Perovskite is a promising alternative due to its weight, flexibility, low fabrication costs, and higher tolerance to radiation than silicon. Perovskites are composed of titanium, calcium, and oxygen atoms that can absorb a large array of the solar spectrum and can be integrated into solar panels.
A perovskite solar cell. Image courtesy of Dennis Schroeder/National Renewable Energy Laboratory
Perovskite can match the efficiency and exceed the performance of silicon at a fraction of the manufacturing cost due to its thin design. So why does silicon still run the show? Perovskite solar cells' main limitation is how quickly they degrade. As soon as PSCs are exposed to sunlight, heat, moisture, or oxygen, the cells begin to corrode, and the cells end up with random defects throughout, making perovskite an unstable choice over silicon.
DIY Turned Full-fledged Laboratory Experiment
What was originally Dr. Laird's at-home DIY machine to analyze various minerals became the talk of the photovoltaic town. Dr. Laird created a device that combines a microscope and a special laser to create images and maps of the defects in PSCs. The device pinpoints the exact location where cells are losing efficiency and power and yields data on why these inefficiencies are occurring in the first place.
The process used in this study is based on intensity modulated photocurrent spectroscopy (IMPS), a frequency domain technique that measures the modulated current responses through different levels of light intensities. Dr. Laird and his fellow researchers at Exciton Science hit a perovskite cell with laser beams to generate a spatial image of the cell's frequency response.
Hitting a Perovskite Cell With Laser Beams
To conduct this study, now published in Small Methods, the Exciton Science team combined the power of microscopy with frequency analysis. First, the researchers put a single perovskite cell under the laser and obtained a scanned image of the cell. They then measured its current and power absorption from the light. Next, the cell was stored in a dark room with low humidity for two weeks. The team hit the cell with the laser again and exposed it to a room with a 50% increase in humidity for another two weeks.
The end results indicated that once the cell was exposed to more moisture, the open-circuit voltage had dropped to nearly half of its original value. They could see what frequency defects were emerging and could present this data to scientists aiming to change the molecular structure of PSCs.
A scanned image of a cell recorded at 1 kHz. Dr. Laird and his team exposed the cell to moisture to see when and where defects would occur. Image used courtesy of Small Methods
Through this at-home project turned lab experiment, the researchers found a way to produce a scan of a perovskite cell that revealed its overall quality.
Dr. Laird's DIY Machine Attracts Attention
In the conclusion of their study, Dr. Laird and his peers at Exciton Science assert that because their technique separates the different components causing cell degradation, it can be a "unique tool" to understand PSC development at a commercial scale.
Other acclaimed research groups have already taken notice of the team's work, including Monash University and Oxford University, which are sending samples of their prototypes to be tested by Dr. Laird's homemade machine. Researchers from the University of Sydney are also on the waiting list to use the testing device for satellites and other space vehicles using experimental solar cells.