Researchers from Seoul National University, University of Pennsylvania, Weizmann Institute of Science and Korea Basic Science Institute (KBSI) recently reported an advancement in the development of ultra-high efficiency perovskite nanocrystal light-emitting diodes (LEDs). Their work involved reinforcing the perovskite lattice and mitigating the material's natural low-frequency dynamics.
The team identified a critical challenge in the reduction of luminescence efficiency due to the ionic nature of perovskite. The weak ionic bonds in perovskite materials can cause large-amplitude displacement of atoms within the crystal lattice, resulting in dynamic disorder that interferes with the radiative recombination process, leading to exciton dissociation and decreased luminescence efficiency. Addressing this issue, however, has been underexplored until now. The team proposed a novel mechanism to enhance the luminescence efficiency of perovskite emitters by incorporating conjugated molecular multipods (CMMs). These CMMs bind to the perovskite lattice, strengthening it and reducing dynamic disorder, which in turn improves the luminescence efficiency.
This work resulted in the creation of ultra-high-efficiency LEDs with an EQE of 26.1%, one of the highest efficiencies recorded in perovskite nanocrystal LEDs. Notably, this improvement was achieved by enhancing the material's intrinsic emission efficiency rather than altering the device structure to boost light outcoupling efficiency.
The perovskite emitters developed by the team may hold great promise as future display technologies. Given that green is a critical color in the Rec. 2020 standard for ultra-high-definition displays, achieving high-efficiency green emitters is crucial. The LEDs created by the team emit light at wavelengths close to the green primary color in the Rec. 2020 standard, potentially accelerating the development of next-generation displays.
Seoul National University's Professor Tae-Woo Lee commented: "This research presents a new material-based approach to overcoming the intrinsic limitations of perovskite light emitters. We anticipate that this will significantly contribute to the development of high-efficiency, long-lifetime perovskite light-emitting devices and the commercialization of next-generation displays."
University of Pennsylvania's Professor Andrew M. Rappe added: "Together we have shown the power of molecules in strengthening perovskites and making them better light emitters. By combining the powers of molecular chemistry, physics, mechanics, and optics, we are inventing new materials to lead us into a bright and energy-efficient future."
