Submitted by Pooja Pandey on Tue, 04/04/2023 - 15:05
Cavendish researchers have demonstrated infrared perovskite LEDs with exceptional performance at high brightness, paving the way towards commercialization and introducing new opportunities beyond conventional LED technologies, such as perovskite electrically pumped lasers which potentially can be used for medical, communications and sensing applications.
Many groups internationally are competing to improve the performance of perovskite LEDs, and using molecular additives is a valuable strategy. What we’ve done in this paper is to understand how and why our molecule improves the efficiency in infrared LEDs, and this gives us a design strategy that we hope will we applicable across the whole visible spectrum in the future. Prof Neil C. Greenham
Solid-state light-emitting diodes (LEDs) are energy-efficient light sources, but they typically require high-vacuum and high-temperature fabrication processes that are expensive and sophisticated. LEDs based on perovskite semiconductors, first demonstrated in Cambridge in 2014, can be fabricated at room temperature based on solution-processing, an inexpensive and easy method. In the past decade, interest in perovskite LEDs has soared and their external quantum efficiencies have risen rapidly so as to be comparable to other emerging materials such as organic semiconductors and quantum dots. Despite reports of quantum efficiencies exceeding 20% in perovskite LEDs since 2018, efficiency drop and limited lifetime at high brightness have held back this technology. Achieving high efficiency, high brightness and longevity simultaneously is the key challenge for commercialisation of perovskite LEDs.
Recently, scientists at the Cavendish Laboratory and the University of Science and Technology of China designed a novel multifunctional molecule to supress non-radiative losses in perovskites and at their interfaces, achieving perovskite LEDs with exceptional performance at high current density and brightness. Reported in Nature, the study demonstrates that the perovskite LEDs can retain high external quantum efficiencies and stability at high brightness levels. This is an important step towards commercialisation and opens up new opportunities beyond conventional LED technologies, such as perovskite electrically pumped lasers which are used for a variety of applications including medical, communications and sensing.
Yuqi Sun, Ph.D. candidate at the Cavendish Laboratory and the lead author of the paper said: “The results shown in this work are encouraging to the scientific community. We are now further investigating the unique device physics of perovskite LEDs, compared to other technologies such as III-V inorganic LEDs and organic LEDs, and understanding the working mechanisms behind their superb performance.”
Prof Lin-Song Cui, a corresponding author who was formerly a postdoctoral researcher at the Cavendish and now a faculty member at the University of Science and Technology of China commented: “Brightness, efficiency and stability are key factors determining the commercialization of perovskite LEDs technology. However, many previous reports often found a trade-off among these factors. Finding a way to make perovskite LEDs bright, efficient and stable concurrently is very important for their commercial use. This work brings us a step closer to this ultimate goal.”
Prof Neil C. Greenham, corresponding author at the Cavendish added: “Many groups internationally are competing to improve the performance of perovskite LEDs, and using molecular additives is a valuable strategy. What we’ve done in this paper is to understand how and why our molecule improves the efficiency in infrared LEDs, and this gives us a design strategy that we hope will we applicable across the whole visible spectrum in the future.”
Reference: Sun, Y., Ge, L., Dai, L. et al. Bright and stable perovskite light-emitting diodes in the near-infrared range. Nature 615, 830–835 (2023). https://doi.org/10.1038/s41586-023-05792-4
Photo: a working infrared LED, captured at high brightness where the camera can detect sufficient emission despite it being outside the normal visible range.
Photo Credit: Yuqi Sun