Infrared photodetectors play a crucial role in various applications, from military infrared guidance to medical imaging. However, traditional photothermoelectric (PTE) photodetectors often lack mechanical flexibility and cannot operate independently without external instruments. Now, researchers from Xi’an Jiaotong University and Tsinghua University, led by Professor Huajing Fang and Professor He Tian, have developed a novel flexible PTE photodetector capable of dual-mode output, combining electrical and optical signal generation. Their findings, published in Nano-Micro Letters, demonstrate a significant advancement in human–machine collaborative infrared imaging.

Why This Dual-Mode Photodetector Matters

• Optimized Responsivity: By employing geometrically asymmetric electrodes, the responsivity of the PTE photodetector is significantly enhanced, achieving 0.33 mA/W under infrared illumination—twice that of symmetric configurations.
• Visual and Machine-Readable Outputs: The photodetector not only generates electrical signals for machine processing but also provides visual indicators through thermochromic composites, enabling direct human perception of infrared radiation.
• Excellent Flexibility: The device maintains stable performance even after 300 bending cycles, making it highly suitable for wearable electronics and flexible devices.

Innovative Design and Mechanisms

• Asymmetric Electrode Design: The use of asymmetric electrodes significantly improves the temperature gradient and enhances the PTE conversion efficiency. This design allows for a greater output current and responsivity compared to symmetric configurations.
• MXene Thin Films: High-quality MXene thin films, known for their excellent photothermal conversion efficiency and conductivity, are used as the photosensitive layer. These films enable efficient conversion of infrared radiation into electrical signals.
• Thermochromic Composites: By integrating thermochromic materials with the photodetector, the device can visualize infrared radiation in real time. The thermochromic composites change color in response to temperature variations, providing a visual indication of infrared signals.

Future Outlook

• Scalability and Practical Applications: The flexible dual-mode photodetector demonstrates strong potential for large-scale production and integration into wearable devices, flexible electronics, and advanced human–machine collaborative systems.
• Further Research: Future work may focus on optimizing the device’s performance, exploring new materials, and developing more complex imaging systems that leverage the dual-mode capabilities.
• Mechanistic Insights: This study provides valuable insights into the role of asymmetric electrode design and MXene thin films in enhancing PTE performance, offering a promising path for the development of next-generation infrared photodetectors.

Stay tuned for more exciting advancements from Professor Huajing Fang and Professor He Tian as they continue to explore the potential of flexible photodetectors and human–machine collaborative technologies!