Vacancy Passivation and ALD Alumina Encapsulation Strategies for Stable Multilayered All-Inorganic Halide Perovskite...

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• White light-emitting diodes (WLEDs) are crucial for lighting and displays, often requiring blue, green, and red emitters for high-quality white light.
• Cesium lead halide perovskite nanocrystals (PNCs) offer high photoluminescence quantum yield (PLQY) for WLEDs but suffer from instability and anion exchange.

Purpose of the Study:

• To enhance the stability and spectral purity of CsPbX3 PNCs for phosphor-converted WLEDs (pc-WLEDs).
• To develop stable, tunable pc-WLEDs using a combined passivation and barrier strategy.

Main Methods:

• Incorporating PbSe islands into CsPbX3 PNCs to passivate halide vacancies.
• Applying an atomic layer deposited (ALD) alumina layer as an ion diffusion barrier.
• Fabricating multilayered and micropatterned pc-WLEDs using spray-coating on glass and PET substrates.

Main Results:

• The strategy effectively suppressed anion exchange, leading to pc-WLEDs stable for over 12 hours of continuous illumination.
• Micropatterned pc-WLEDs demonstrated excellent thermal stability, with emissive layers remaining stable after 20 heating/cooling cycles.
• Correlated color temperature (CCT) was tunable from 4595 to 5010 K by adjusting driving current.

Conclusions:

• The combined PbSe passivation and ALD alumina barrier strategy significantly improves the stability of CsPbX3 PNCs for pc-WLED applications.
• Developed pc-WLEDs exhibit robust performance, tunable color temperature, and potential for flexible electronics.