Performance improvement of an upconversion device through optimized carrier injection balance

Area of Science:

• Optoelectronics
• Materials Science
• Photonics

Background:

• Carrier injection balance is critical for efficient and stable operation of upconversion devices (UCDs).
• Existing UCDs often suffer from imbalanced carrier injection, limiting their performance.
• Near-infrared (NIR) to visible upconversion is essential for applications like bioimaging.

Purpose of the Study:

• To enhance carrier injection balance in NIR to visible UCDs.
• To improve the efficiency, stability, and performance of UCDs.
• To explore the potential of UCDs in bioimaging applications.

Main Methods:

• Incorporation of an insulating polymer, polymethyl methacrylate (PMMA), between the aluminum cathode and electron transport layer.
• Fabrication of UCDs with and without the PMMA interlayer for comparison.
• Characterization of device performance, including luminance, efficiency, optical response, and resolution.

Main Results:

• The optimized UCD with PMMA showed a fivefold increase in maximum luminance and upconversion efficiency.
• The PMMA interlayer effectively reduced excess electrons, balancing carrier injection.
• The device exhibited a fast optical response, broad modulation range, and a maximum resolution of 1693 dpi for bioimaging.

Conclusions:

• The integration of a PMMA interlayer is an effective strategy to improve carrier injection balance in UCDs.
• This approach significantly enhances the performance and stability of NIR to visible UCDs.
• The optimized UCDs show great promise for advanced bioimaging applications.