Working Voltage Switching the Photo-/Thermo-Electric Effect for Distinct Ultraviolet and Infrared Signal Detection

Area of Science:

• Materials Science
• Optoelectronics
• Photonics

Background:

• Combining ultraviolet (UV) and infrared (IR) sensing improves target recognition by addressing limitations of short sensing range and poor spatial resolution.
• Distinct wavelength requirements for UV and IR sensing pose challenges for integration into a single detector.

Purpose of the Study:

• To design and demonstrate a single detector capable of distinguishing UV and IR signals.
• To leverage the photo- and thermoelectric effects of a single material for dual-mode sensing.

Main Methods:

• Utilized methylammonium lead chloride (CH3NH3PbCl3, MAPbCl3) as the sensing material.
• Exploited the large optical band gap (~3.2 eV) of MAPbCl3 for UV photon detection.
• Leveraged the efficient thermoelectric properties of MAPbCl3 for IR radiation sensing.
• Switched operating modes via applied voltage to differentiate between UV and IR signals.

Main Results:

• Achieved a specific detectivity of 4.5 × 10^12 Jones for 395 nm UV photons at 0 V.
• Demonstrated a temperature coefficient of resistance of -3.7% K^-1 at 2.5 V.
• Obtained a specific detectivity of 4.8 × 10^8 Jones and a limit of detection of 0.58 mW/cm^2 for 4 μm IR photons at 2.5 V.

Conclusions:

• The MAPbCl3-based single detector successfully distinguishes UV and IR signals by switching operating modes.
• This dual-mode sensing capability enables background subtraction and enhances target discrimination in imaging applications.