Perovskite heteroepitaxy for high-efficiency and stable pure-red LEDs

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Ultrasmall cesium lead iodide perovskite quantum dots (CsPbI3 QDs) are promising for pure-red perovskite light-emitting diodes (PeLEDs).
• Challenges exist in maintaining the solution-phase properties of CsPbI3 QDs when forming conductive films, limiting device applications.

Purpose of the Study:

• To develop a method for in situ deposition and stabilization of ultrasmall CsPbI3 QD conductive solids.
• To enable the fabrication of efficient and stable pure-red PeLEDs using stabilized CsPbI3 QDs.

Main Methods:

• Constructing CsPbI3 QD/quasi-two-dimensional (quasi-2D) perovskite heteroepitaxy.
• Utilizing edge-oriented ligands at the heterointerface to induce octahedral tilting and thermodynamic stabilization of CsPbI3 QDs.

Main Results:

• Fabricated stabilized CsPbI3 QD conductive films with tunable emission from 600 nm to 710 nm.
• Achieved pure-red PeLEDs with a narrow electroluminescence peak at 630 nm, meeting Rec. 2100 standards.
• Champion device demonstrated a 24.6% external quantum efficiency (EQE) and a 6,330-minute half-lifetime.
• Large-area (1 cm²) PeLEDs achieved a 20.5% EQE at 630 nm.

Conclusions:

• The heteroepitaxy approach effectively stabilizes ultrasmall CsPbI3 QDs in conductive films.
• This method enables the creation of highly efficient and stable pure-red PeLEDs suitable for ultrahigh-definition displays.
• The technique is compatible with large-area manufacturing, paving the way for commercial applications.