Synergistic Narrowing in Perovskite/Organic Quasi-Homojunction Enables Near-Infrared Band-Pass Weak-Light Detection

Area of Science:

• Materials Science
• Optoelectronics
• Photonics

Background:

• Near-infrared (NIR) band-pass photodetection is crucial for applications like optical sensing, biomedical imaging, and secure communications.
• Conventional methods face challenges in achieving high responsivity and low noise under weak-light conditions due to interfacial traps and incomplete photon suppression.
• Existing internal filtering strategies often compromise device efficiency.

Purpose of the Study:

• To develop a novel perovskite/organic quasi-homojunction for synergistic spectral narrowing and improved NIR photodetection.
• To overcome limitations of conventional filtering strategies by reducing trap-state density and enhancing efficiency.
• To achieve high-performance, self-powered NIR photodetectors suitable for nanowatt-level illumination.

Main Methods:

• Fabrication of a perovskite/organic quasi-homojunction device.
• Utilizing a perovskite front layer for visible light attenuation.
• Employing an acceptor-rich organic layer to establish a uniform transport field for efficient NIR carrier extraction.
• Investigating the synergistic effect of optical filtering and transport field on device performance.

Main Results:

• The quasi-homojunction achieved synergistic spectral narrowing, enhancing selectivity and reducing trap-state density.
• The device demonstrated a self-powered NIR-I (700-950 nm) response.
• Achieved high external quantum efficiency of ~70% and zero-bias responsivity of 0.45 A W⁻¹.
• Outperformed previously reported perovskite/organic band-pass photodetectors.

Conclusions:

• The integrated strategy of intrinsic optical filtering and uniform transport field is effective for high-performance NIR photodetectors.
• The developed device shows significant potential for applications requiring sensitive detection under weak-light conditions.
• This approach offers a promising pathway for advancing optical sensing and imaging technologies.