PbS Capped CsPbI₃ Nanocrystals for Efficient and Stable Light-Emitting Devices Using p-i-n Structures

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Cesium lead halide perovskite nanocrystals (NCs) exhibit excellent optical properties like high color purity and photoluminescence (PL) efficiency.
• A major limitation for their application in light-emitting diodes (LEDs) is the low external quantum efficiency (EQE) stemming from surface defects.

Purpose of the Study:

• To develop a surface passivation strategy for CsPbI3 NCs to improve their performance in LEDs.
• To investigate the impact of PbS capping on the optical and electrical properties of CsPbI3 NCs and their application in LEDs.

Main Methods:

• Passivation of CsPbI3 NCs by capping with lead sulfide (PbS).
• Fabrication of electroluminescence LEDs using p-i-n structures with PbS-capped CsPbI3 NCs.
• Characterization of optical properties (PL efficiency, Stokes shift, PL bandwidth) and electrical properties (type behavior) of the NCs and LEDs.

Main Results:

• PbS capping significantly enhanced PL efficiency, reduced Stokes shift, narrowed PL bandwidth, and improved the stability of CsPbI3 NCs.
• PbS capping shifted the electrical behavior of CsPbI3 NC films from n-type to nearly ambipolar.
• The fabricated LEDs demonstrated improved storage and operation stability, achieving an EQE of 11.8%.

Conclusions:

• Surface passivation using PbS is an effective strategy to mitigate defects in CsPbI3 NCs.
• PbS-capped CsPbI3 NCs are promising for next-generation LED and display applications due to enhanced performance and stability.