Effective near-infrared (NIR) light-emitting diodes of perovskite have actually been produced in a lab at Linköping University. The external quantum efficiency is 21.6%, which is a record. The outcomes have actually been released in Nature Photonics.
The work is led by LiU researcher Feng Gao, in close partnership with associates in China, Italy, Singapore and Switzerland.
Perovskites are a group of products specified by their crystal structure, and have actually been the focus of extreme research study interest throughout the past 10 years, at first for solar batteries and just recently likewise for light releasing diodes. They have excellent light-emitting residential or commercial properties and are simple to make. The external quantum efficiency (the ratio of charge providers produced as light over all of those fed into the products) of light-emitting diodes based upon perovskites has actually previously been restricted by flaws that develop in the product throughout manufacture. The flaws serve as traps for the charge providers and hence trigger energy losses.
One method of handling flaws is to include products referred to as “passiviation molecules”, which bind to the atoms that trigger flaws. The scientists had actually formerly found a particle with amino groups at its ends that provided a specific enhancement in residential or commercial properties. Nevertheless, when they chose a particle that likewise included oxygen atoms, the result increased drastically.
“We now understand that it is the hydrogen bonds between passivation molecules and perovskite materials that cause problems. This allowed us to search for a molecule that was perfect for passivation”, states Feng Gao, senior speaker in the Department of Biomolecular and Organic Electronic Devices at Linköping University.
The particle they discovered has 2 amino groups at its ends, with oxygen atoms at ideal ranges in between them. Oxygen atoms lower the hydrogen bonding capability of amino groups, and for this reason increase the possibility that they engage with flaws. The variety of traps for charge providers in the perovskite is considerably lowered, enabling the charge providers to recombine and give off light effectively.
“This particular perovskite material gives highly efficient light-emitting diodes in the near-infrared region. Near-infrared light-emitting diodes are particularly useful for medical and telecommunication applications. We believe that our new findings can also be applied to perovskite light-emitting diodes with other colours”, states Feng Gao.
The external quantum efficiency is a record-high 21.6%.
“We have developed the best light-emitting diodes in perovskite material yet. They can also compete with light-emitting diodes based on, for example, organic materials”, states Wiedong Xu, postdoc in the Department of Biomolecular and Organic Electronic Devices, LiU.
One source of financing for the research study has actually been Feng Gao’s ERC Beginning Grant. Feng Gao is likewise Wallenberg Academic Fellow, and Wiedong Xu is a Wenner-Gren Postdoc Fellow.
Logical molecular passivation for high-performance perovskite light-emitting diodes
Weidong Xu, Qi Hu, Sai Bai, Chunxiong Bao, Yanfeng Miao, Zhongcheng Yuan, Tetiana Borzda, Alex J. Barker, Elizaveta Tyukalova, Zhangjun Hu, Maciej Kawecki, Heyong Wang, Zhibo Yan, Xianjie Liu, Xiaobo Shi, Kajsa Uvdal, Mats Fahlman, Wenjing Zhang, Martial Duchamp, Jun-Ming Liu, Annamaria Petrozza, Jianpu Wang, Li-Min Liu, Wei Huang, and Feng Gao. Nature Photonics 2019. doi 10.1038/s41566-019-0390-x