Researchers from Jilin University, Fudan University, the Chinese Academy of Sciences (CAS), Beijing Jiaotong University, and Southeast University have developed a new design strategy for metal halide perovskite light-emitting diodes (PeLEDs) that improves their performance while simplifying fabrication. Their work introduces a spontaneously formed 3D/2D vertically oriented perovskite heterojunction, created via a simple one-step spin-coating process that simultaneously improves charge confinement, light extraction, and operational stability.
PeLEDs hold great promise for next-generation displays and lighting due to their tunable colors, high brightness, and low manufacturing costs. However, their efficiency has traditionally fallen short of organic LEDs (OLEDs) - which can reach ~40% external quantum efficiency (EQE) - because of insufficient charge confinement and non-radiative recombination losses at defect-rich surfaces.
The team’s new device structure effectively tackles these issues. During spin-coating, the perovskite film self-organizes into a vertically aligned 3D/2D heterostructure: a three-dimensional emission layer beneath a thin two-dimensional perovskite capping layer. The 2D layer naturally forms on top due to controlled crystallization dynamics, creating a smooth vertical energy landscape that confines electrons and holes in the emissive zone while isolating them from defect-prone surfaces.
Interestingly, the 2D top layer displays a wrinkled morphology that boosts light extraction efficiency to 45.4% - one of the highest values reported for PeLEDs - by scattering and redirecting internally trapped photons. The resulting green-emitting PeLEDs achieved a record EQE of 42.9% (certified 42.3%), essentially matching or surpassing the best-performing OLEDs while maintaining simple, low-cost processing.
The vertically oriented heterojunction promotes spatial separation between radiative and non-radiative regions: charge carriers recombine predominantly within the high-quality 3D bulk, whereas the 2D surface layer acts as an energy barrier and moisture-resistant encapsulant. This design minimizes energy loss routes and enhances both luminous efficiency and environmental stability.
These results mark a step toward commercial viability for perovskite-based LEDs. By enabling near-OLED efficiency with a scalable, single-step process, the study demonstrates how rational heterostructure engineering can turn perovskite PeLEDs into practical contenders for consumer displays, lighting panels, and other advanced optoelectronic applications.
