When synthetic materials called perovskites made their solar cell debut in 2012, they were touted for being cheap and easy to produce. Despite these advantages, they just weren’t efficient enough to compete with silicon. Scientists spent the next few years improving perovskite technology so that it became almost as good as conventional silicon cells. Now, researchers at the University of Cambridge have discovered perovskite’s hidden talent: photon recycling. This could be a game changer.
The researchers demonstrated that hybrid lead halide perovskites can be optimized to re-absorb photons. In other words, it recycles light. They shined a laser on a sample perovskite and measured the photon activity based on the light the material emitted. As expected, they observed near-infrared light emission where the laser was pointed and at other areas in the sample. However, then they observed a second, bonus emission, made of lower-energy photons.
The low-energy component enables charges to be transported over a long distance, but the high-energy component could not exist unless photons were being recycled. Recycling is a quality that materials like silicon simply don’t have. This effect concentrates a lot of charges within a very small volume. These are produced by a combination of incoming photons and those being made within the material itself, and that’s what enhances its energy efficiency.
The study is described in a research paper that published in Science on March 25.
