Research teams from universities such as Northwestern Polytechnical University have made significant breakthroughs in the field of perovskite LED research

Recently, a team led by Academician Huang Wei from Northwestern Polytechnical University, Associate Professor Zhu Lin from Nanjing Polytechnical University, and Professor Wang Jianpu from Changzhou University have made significant breakthroughs in the research field of perovskite light-emitting diodes (LEDs): by accelerating the radiation recombination rate and significantly improving the fluorescence quantum efficiency, the external quantum efficiency of perovskite LEDs has exceeded 30%, approaching the level of industrialization.

 The related achievements were published in the top international academic journal Nature under the title "Acceleration of radial recombination for effective perovskite LEDs".

 LED is a key core technology in the field of new displays, playing an important role in high-end manufacturing and a typical representative of new quality productivity. Thin film LED technology is a type of technology that can prepare LED devices on any substrate (including flexible) in large areas, and is also an advanced technology widely adopted in the mainstream manufacturing of mobile phone display screens. With the continuous development of the global new display industry and application fields, the research and development of high-performance thin film LEDs with lower costs, higher brightness, and better light efficiency in the technology community is becoming more and more in-depth.

 LED based on perovskite semiconductor materials is an emerging type of thin film LED, which has the characteristics of simple processing technology, high brightness and efficiency. In recent years, it has attracted attention in the field of optoelectronic device research and has become the focus of global competition for new luminescent and display technologies.

 The innovation team led by Academician Huang Wei and Professor Wang Jianpu is a pioneer and leader in the research of perovskite LEDs internationally. Ten years ago, they utilized interface control to construct high-efficiency devices, breaking through the bottleneck of 1% external quantum efficiency in perovskite LEDs internationally.

 In 2016, they achieved efficient luminescence through multiple quantum well perovskites, effectively suppressing non radiative recombination and setting a world record for external quantum efficiency exceeding 10%.In 2018, they used solution based self-assembly to form submicron structures and constructed a new type of device that is easy to couple with light, achieving an external quantum efficiency of over 20% and once again breaking a milestone.

 The research results of the team have had a significant impact on the global research field of perovskite LEDs, providing valuable reference for colleagues at home and abroad to explore high-efficiency perovskite LEDs. The high-level research results published by the team in the field of perovskite LEDs rank first in the world in the international authoritative technology database - "Research Frontiers" published by Korui Weian.

 There are two types of perovskite luminescent materials: three-dimensional and low dimensional. Among them, three-dimensional perovskite has the most potential to achieve high efficiency luminescence at high brightness, which is of great significance for the industrialization of future luminescent display technology. However, the external quantum efficiency of 3D perovskite LEDs is generally around 20%, and the overall performance improvement is facing a bottleneck.

 The external quantum efficiency is determined by both fluorescence quantum efficiency and light extraction efficiency. Currently, the limitation of device light extraction efficiency has been overcome, but the improvement of fluorescence quantum efficiency has not met expectations. Fluorescence quantum efficiency is the result of competition between radiative recombination and non radiative recombination processes. In other words, in order to improve fluorescence quantum efficiency, it is necessary to suppress non radiative recombination and enhance radiative recombination.

 In previous studies, defect passivation was mostly used to suppress non radiative recombination, but even though the defect density of three-dimensional perovskite films has decreased to the level of single crystal perovskite, the fluorescence quantum efficiency still generally remains around 70% Professor Wang Jianpu introduced the difficulties in improving the fluorescence quantum efficiency of three-dimensional perovskite materials in the field.

 To solve this global problem, the team has taken a different approach and creatively proposed a method of regulating crystal growth to generate perovskite crystal phases with faster radiation recombination rates, thereby significantly improving fluorescence quantum efficiency.

 At the same time, the team cleverly utilized this innovative method to successfully maintain the submicron structure of the three-dimensional perovskite, ensuring that the light extraction efficiency of the device is not affected, achieving a dual effect. This study achieved a fluorescence quantum efficiency of 96% and a light extraction efficiency greater than 30%, and further prepared efficient perovskite LEDs with an external quantum efficiency of 32%, once again setting a world record for the luminescence efficiency of perovskite LEDs.

 "We also found that the device can maintain high efficiency even at high brightness, and even at a high current density of 100 milliamperes per square centimeter, the external quantum efficiency can still be maintained at 30%," said Associate Professor Zhu Lin. When it comes to the development of perovskite LEDs, Academician Huang Wei is very excited to say that this major breakthrough further demonstrates the enormous potential of thin film LED technology based on perovskite semiconductor materials, and will undoubtedly promote the industrialization of display technology based on perovskite LEDs. Meanwhile, it indicates its broad application prospects in the field of efficient green lighting. "In addition, this innovative breakthrough was also achieved by our team with long-term support from national key research and development programs, national basic science centers, and other scientific research projects, in collaboration with multiple advantageous units in the field of flexible electronics in China, including Nanjing University of Technology, Fujian Normal University (Straits Innovation Laboratory), Fudan University, Zhejiang University, Sun Yat sen University, Changzhou University, and University of Macau. It fully reflects the important role of interdisciplinary and collaborative innovation," added Academician Huang Wei.