Photon recycling: The secret to high-efficiency perovskite solar cells

• Scientists from TU Dresden, in cooperation with researchers at Seoul National University (SNU) and Korea University (KU), demonstrated the role of the re-use of photons (called 'photon recycling') and also light scattering effects in perovskite solar cells, supplying a pathway towards high-efficiency solar energy conversion. The study has been published in Science Developments.

Steel halide perovskites are receiving excellent attention as next-generation semiconductors for solar energy conversion. Because the very first demo of 3.8 percent efficiency in 2009, performances have increased quickly and also state-of-the-art perovskite solar cells exhibit high efficiencies over 25 percent, close to the document effectiveness of silicon photovoltaics. This quick growth throughout the last decade raises the concern of whether perovskite solar cells will have the ability to get to the top (thermodynamic) limitation of photovoltaic or pv performance, which is known to be 34 percent in single-junction semiconductors. To approach this objective, it is theoretically known that the solar cell has to not only be an excellent light absorber, yet likewise be a great light emitter.

The scientists from the Dresden Integrated Center for Applied Physics as well as Photonic Materials (IAPP) at the TU Dresden noted the role of the photon recycling impact. When a photon is emitted inside re-absorbing semiconductors such as perovskites, it can be re-absorbed by the emitter itself as well as generate a brand-new photon through photoluminescence. Such a process of recursively re-absorbing and also re-emitting the photons is called photon recycling. While this sensation has been previously demonstrated by a number of research groups, its useful contribution to the performance of perovskite solar cells has been under extensive dispute. Based upon the devices prepared by the teams in SNU and also KU, the IAPP scientists uncovered that photon recycling and also light scattering effects substantially improve the light exhaust performance by a factor of ~ 5, considerably boosting the photovoltage of perovskite solar cells.

Their work exposes the useful benefits of photon recycling in perovskite solar cells. "Perovskites are currently great absorbers. Currently it's time to improve their light-emitting ability, to even additional enhance their currently high power conversion efficiencies," claims Dr. Changsoon Cho, that led the work as a Humboldt study fellow at IAPP. "Understanding photon recycling is a crucial step in the direction of this direction." The work anticipates that the payment of photon recycling, along with the reductions of numerous optoelectrical losses, will cause a further increase in efficiency in the future. Using photon recycling, the upper limit for the performance of the perovskite solar cells is shown to increase from 29.2 percent to 31.3 percent.

"With the fundamental understandings pertaining to the role of photon recycling at hand, we have a distinct possibility to additionally boost the perovskite solar cell effectiveness, hence offering this innovation ever before brighter leads to compete with the well-established silicon-based photovoltaics," adds Prof. Yana Vaynzof, Chair of Emerging Electronic Technologies at the Institute of Applied Physics and the Center for Advancing Electronics Dresden (cfaed). Indeed, the renovations in the potential of perovskite solar cells motivate to additional seek the commercialization of this technology. "Our study reveals the potential of the technology, but a lot more effort in r & d is needed before the innovation can go into mass production," says Prof. Karl Leo, head of the IAPP as well as European Innovator Award champion.