Quantum Dot-Based Three-Stack Tandem Near-Infrared-to-Visible Optoelectric Upconversion Devices.

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Quantum dots (QDs) offer tunable optical properties for light-sensing and emission.
• Tandem devices convert near-infrared (NIR) to visible (Vis) signals but face processing challenges.
• Existing methods limit QD upconversion device structures due to layer sensitivity.

Purpose of the Study:

• To present a modular fabrication approach for QD-based optoelectric upconversion devices.
• To overcome processing limitations in tandem QD device construction.
• To improve NIR-to-Vis photon conversion efficiency.

Main Methods:

• Developed NIR QD-absorbing (Abs) and Vis QD-electroluminescence (EL) modules with cross-linked, dissolution-tolerant layers.
• Fabricated tandem devices in normal (EL on Abs) and inverted (Abs on EL) configurations.
• Constructed a three-stack tandem device with one NIR Abs unit and two Vis EL units.

Main Results:

• The modular approach enables robust fabrication of tandem QD devices.
• Normal structure tandem devices achieved a NIR-to-Vis photon conversion efficiency of up to 1.9%.
• The three-stack device demonstrated a higher conversion efficiency of up to 3.2%.

Conclusions:

• The modular QD approach provides structural tolerance, simplifying tandem device fabrication.
• This method enhances efficiency for QD-based optoelectric upconversion devices.
• The strategy is extendable for multi-stack configurations, boosting conversion efficiency.