Reviewed by Lexie CornerJul 8 2024
A team of scientists led by Professor Xuyong Yang from the Ministry of Education’s Key Laboratory of Advanced Display and System Applications at Shanghai University, China, and colleagues developed a durable, effective, and high-color purity hybrid LED with a tandem structure. They achieved this by combining perovskite LED and commercial organic LED technologies to speed up the practical application of perovskites.
a, Device structure and b, schematic energy band diagram of a hybrid LED. c, EL spectra, d, current density-voltage, e, luminance-voltage and f, EQE- current density characteristics of the PeLED, OLED and hybrid LED. The star marks the maximum EQE value. Inset in (f) is a photo of a hybrid LED operated under biased voltage of 7.5 V, with an active area of 30 mm × 30 mm. Image Credit: Lingmei Kong, Yun Luo, Qianqian Wu, Xiangtian Xiao, Yuanzhi Wang, Guo Chen, Jianhua Zhang, Kai Wang, Wallace C. H. Choy, Yong-Biao Zhao, Hongbo Li, Takayuki Chiba, Junji Kido, and Xuyong Yang
Light-emitting diode (LED), a key component of display technology, is required to meet the Rec. 2020 color gamut standard for next-generation display applications. Metal-halide perovskites offer highly narrowband emissions and easily configurable bandgaps, making them one of the few types of emitters that can now completely fulfill Rec.2020.
Perovskite LEDs (PeLEDs) have advanced quickly in the last few years, and their current external quantum efficiency (EQE) is close to 30 %, which is on par with commercial organic LEDs (OLEDs). Nevertheless, perovskites' inherent instability continues to raise questions about their applicability.
Combining highly color-purity perovskite emitters with other established display technologies, such as OLEDs, to broaden the display color gamut might offer a quick path to commercialization for high-definition screens.
PeLED and OLED with close photoluminescence peaks are chosen to increase photon emission while avoiding photon reabsorption and producing narrowed emission spectra. The resulting green emitting hybrid LED has a narrow line width of around 30 nm, a peak luminance of over 176,000 cd m-2, a maximum external quantum efficiency of over 40 %, and an operational half-lifetime of over 42,000 h.
This is achieved by developing an efficient interconnecting layer with p-type interface doping that provides good opto-electric coupling and reduces Joule heating.
Journal Reference:
Kong, L., et al. (2024). Efficient and stable hybrid perovskite-organic light-emitting diodes with external quantum efficiency exceeding 40 per cent. Light Science & Applications. doi:10.1038/s41377-024-01500-7