Short-Wave Infrared InAs Quantum-Dot Light-Emitting Diodes with Tunable Electroluminescence beyond 1.4 μm

Area of Science:

• Materials Science
• Quantum Dot Technology
• Optoelectronics

Background:

• Colloidal quantum dots (QDs) are crucial for short-wave infrared (SWIR) optoelectronics.
• Current SWIR QD technology heavily relies on hazardous heavy-metal chalcogenides like PbS and HgTe.
• There is a need for safer, high-performance alternatives.

Purpose of the Study:

• To develop Restriction of Hazardous Substances (RoHS)-compliant quantum dot light-emitting diodes (LEDs) for SWIR applications.
• To demonstrate efficient electroluminescence (EL) from InAs/ZnSe core/shell QDs beyond 1100 nm.
• To advance III-V QDs for SWIR optoelectronic systems.

Main Methods:

• Synthesis of InAs cores using a tris-(dimethylamino)-arsine-based continuous-injection method for precise size control.
• Fabrication of InAs/ZnSe core/shell QDs.
• Development of a hybrid charge-injection stack with organic (poly-TPD/PTAA) and inorganic (ZnMgO) transport layers.
• Characterization of LED performance, including electroluminescence (EL) spectra and external quantum efficiencies (EQEs).

Main Results:

• Demonstrated RoHS-compliant InAs/ZnSe core/shell QD LEDs operating in the SWIR range.
• Achieved EL peak emission wavelengths at 1007, 1275, 1300, and 1410 nm.
• Reported peak external quantum efficiencies (EQEs) of 6.20%, 3.75%, 2.04%, and 1.10% for the respective LEDs.
• Achieved the first demonstration of EL from InAs QDs beyond 1100 nm.

Conclusions:

• The developed InAs/ZnSe core/shell QDs offer a promising, heavy-metal-free alternative for SWIR optoelectronics.
• The hybrid charge-injection stack effectively balances charge injection for efficient light emission.
• These findings pave the way for advanced SWIR applications in machine vision and bioimaging.