High-Performance Up-Conversion Photodetectors with Zero-Barrier Interconnection via Self-Assembled Surface Dipoles

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Lead sulfide (PbS) quantum-dot photodetectors face performance limitations due to high potential barriers at the photodetecting (PD)/light-emitting (LED) interface.
• This necessitates high driving voltages, leading to increased energy consumption and reduced operational stability.

Purpose of the Study:

• To overcome the limitations of PbS quantum-dot up-conversion photodetectors by engineering the PD/LED interface.
• To achieve a zero-barrier interconnection, reduce driving voltage, and enhance photon-to-photon conversion efficiency.

Main Methods:

• Introduction of azetidinium iodide (AzI) at the interface between the photodetecting (PD) and light-emitting (LED) units.
• Investigation of the self-assembly mechanism of AzI dipole molecules at the interface.
• Characterization of the device performance under infrared illumination.

Main Results:

• Achieved a zero-barrier interconnection in PbS-based infrared up-conversion photodetectors.
• Reduced the turn-on voltage to 1.2 V under infrared illumination.
• Obtained a high photon-to-photon conversion efficiency (ηpp) of approximately 3% at 3 V, a tenfold improvement over previous devices.

Conclusions:

• Azetidinium iodide (AzI) effectively regulates interface energy level alignments through self-assembly driven by van der Waals forces.
• The developed interface modification strategy significantly enhances the performance of PbS quantum-dot up-conversion photodetectors.
• This breakthrough offers a pathway towards more energy-efficient and stable infrared optoelectronic devices.