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Pi-Tai Chou, Nature Photonics, near infrared, organic light-emitting diode, OLED, GIXD, energy gap law
NSRRC User Prof. Pi-Tai Chou's Research Published in the Prestigious Journal Nature Photonics
2020/07/24
NSRRC user Pi-Tai Chou is Professor in Chemistry and Director of Center for Emerging Material and Advanced Devices at National Taiwan University. A research team spanning multiple universities and led by him recently published their latest research results in Nature Photonics, a top-ranking journal in the field of photonics. The research has overcome the long-standing restriction of molecular emission in the near infrared (NIR) region and could facilitate the development of high-performance NIR organic light emitting diodes (OLEDs), which can be applied to bio-medical infrared imaging, infrared therapy, infrared face recognition for mobile phones, and infrared for distance measuring and night vision.

The development of high efficient NIR OLEDs used to be hindered by strong non-radiative processes as governed by the energy gap law. In Prof. Chou's research paper titled "Overcoming the energy gap law in near-infrared OLEDs by excitation-vibration decoupling", he proposed that exciton delocalization could bring substantial enhancements in the photoluminescence quantum yield of emitters, bypassing the energy gap law. The team members used the grazing incidence X-ray diffraction (GIXD) technique of BL13A1 and BL01C2 at Taiwan Light Source (TLS) to measure the packing and orientation of the molecular assembly, calculate the electron density map, and further explain the characteristics of the new Pt(II) complexes they designed and synthesized. Both theoretical and experimental results confirmed the proposed strategy, which should be broadly applicable to other well-aligned molecular solids. The research results that could make a breakthrough in related applications have attracted a great deal of international attention.