Japanese researchers developed a new method to build large perovskite solar panels with a longer lifespan than ever achieved, according to a new study published on Advanced Energy Materials (1). Using this procedure, the team built two large perovskite solar modules – 5×5 cm2 and 10×10 cm2 – and kept both working for over 1000 hours. This is a record time for modules this size. These results are a significant step forward to produce efficient and durable perovskite solar panels, which could be commercially available in just a few years.
Many believe perovskite will revolutionise the manufacture of solar panels. The perovskite used in these panels is a synthetic form, but it’s a copy from a natural mineral with the same name originally found in the Ural Mountains of Russia more than 100 years ago. This mineral is composed of at least three different chemical elements arranged in a complex cubic structure. Typically, solar panels use lead as the as the light-harvesting component.
However, this technology is not quite ready for the market yet. A few hurdles are blocking the way into full-blown commercialisation, including a short lifespan and low efficiency when scaled up. “Perovskite material is fragile and prone to decomposition, which means the solar cells struggle to maintain high efficiency over a long time,” said first author of the study, Dr Guoqing Tong, based at the Okinawa Institute of Technology in Japan. “And although small-sized perovskite solar cells have a high efficiency and perform almost as well as their silicon counterparts, once scaled up to larger solar modules, the efficiency drops.”
At first, scaling up the size of the panels was really frustrating. When building larger cells, it was virtually impossible to make a uniform layer of perovskite and flaws rapidly became noticeable. After trial and error, the solution was to create a layer twice as thick. This decision came with its own set of challenges, but eventually the team discovered that adding ammonium chloride to the solution allowed them to use higher amounts of lead iodine needed to make ticker layers. This way, lead iodine was evenly dissolved, resulting in a more uniform perovskite layer with fewer blemishes.
Thanks to this method, the team successfully built two squares, sized 5×5 cm2 and 10×10 cm2. This is an incredible jump from the 1.5×1.5 cm2 traditionally built in the lab, but still smaller than commercial solar panels, which are at least 18×18 cm2.
With an efficiency of 15%, the smaller device worked for 1,600 hours while the larger square run with slightly lower values, with an efficiency of 10% and over 1,100 hours running time. Although smaller panels in lab conditions can run for much more extended periods with higher efficiencies, this is the longest lifespan measurement recorded for modules this size. It may not seem much, but these results are an incredible advancement on the road to produce solar panels which are at least as efficient and durable as standard silicon panels.
In the future, the team wants to continue improving their solar cells and are aiming to reach 15×15 cm2 squares. “Going from lab-sized solar cells to 5×5 cm2 solar modules was hard. Jumping up to solar modules that were 10×10 cm2 was even harder. And going to 15×15 cm2 solar modules will be harder still,” said Dr Tong. “But the team is looking forward to the challenge.”
Although there are still issues to solve, it’s only a matter of time until these solar cells are widely available to buy. Perovskite has a tremendous potential and low-cost, high efficiency, eco-friendly and long lifespan solar panels are just around the corner.
What’s more, perovskite is not just for solar panels. These minerals are fascinating nanomaterials with intriguing properties and lend themselves perfectly to many innovative discoveries for new devices. Perovskite’s potential applications include uses in sensors and catalyst electrodes, certain types of fuel cells, lasers, sensors, memory devices and spintronics applications, to name just a few.
(1) Tong G et al. Scalable Fabrication of >90 cm2 Perovskite Solar Modules with >1000 h Operational Stability Based on the Intermediate Phase Strategy. Advanced Energy Materials (2021) DOI: 10.1002/aenm.202003712