Prof. Tae-Woo Lee and Students Develop Perovskite LED That Could Replace LED and OLED
Prof. Tae-Woo Lee and his students Himchan Cho, Su-Hun Jeong, and Min-Ho Park (Dept. of Materials Science and Engineering), are the first to develop a perovskite light emitting diode (PeLED) that could replace organic LED (OLED) and quantum dot LED (QDLED). Their research was published in Science on December 4.
The display market has been interested in developing high-efficiency, high-color purity, and low-cost emitters for use in TVs, mobile phones, lighting and other electronic devices. OLEDs have a very high luminous efficiency, but low color purity that provides a limited natural color gamut. High material cost, complex color-tuning process, and low charge carrier mobility of OLEDs are other drawbacks. QDLEDs were suggested as an alternative to overcome low color purity of OLEDs, however, they also have high materials cost and are difficulty in uniform control of QD size.
Organic/inorganic hybrid perovskite has much higher color-purity at a lower cost compared to organic emitters and inorganic QD emitters. However, LEDs based on perovskite had previously shown a limited luminous efficiency, mainly due to significant exciton (a complex of an electron and hole that can make light emission when it is radiatively recombined) dissociation in perovskite layers.
The research team overcame the efficiency limitations of PeLED and boosted its efficiency to a level similar to that of phosphorescent OLEDs. This increase was attributed to fine stoichiometric tuning that prevents exciton dissociation, and to nanograin engineering that reduces perovskite grain size, and concomitantly decreases exciton diffusion length.
It is expected that PeLED can be a game changer in the industries of displays and solid-state lighting with significantly improved efficiency as well as its own advantages including excellent color gamut and low material cost.
Prof. Tae-Woo Lee mentioned, “This study can attract researchers’ interest toward perovskite materials over the world, and show great potentials of perovskite materials for other optoelectronic devices, not only for solar cells.”