- Development of an ultra-low-power, high-sensitivity near-infrared optical sensor based on amplified bipolar phototransistors

- Expanded potential for next-generation optical sensor integration through simultaneous implementation of P- and N-type photodetection

- Presents potential applications such as LiDAR  and noncontact sensors for physical AI-based intelligent sensing

  A joint research team led by Professor Hyeok Kim of the School of Electrical and Computer Engineering at the University of Seoul and Professor Yongju Lee of the Department of Semiconductor Engineering at Dong-a University has developed a ambipolar organic phototransistor capable of detecting near-infrared (NIR) light with high sensitivity—even at low voltages of 5 V or less—while simultaneously achieving both P- and N-type operations in a single organic semiconductor material.

  The research team successfully detected dynamic NIR signals in real time, thereby demonstrating potential applications in LiDAR , contactless sensors, and next-generation optoelectronic devices.

  The results of this study were published on April 27, 2026, in the prestigious journal Small (impact factor: 12.1), issued by Wiley, under the title “Low-Voltage, High-Sensitivity NIR Ambipolar Organic Phototransistor Based on a Non-Fullerene Acceptor.” Researchers Hwapyeong Noh and Swarup Biswas served as co-first authors, Professor Yongju Lee participated as a co-author, and Professor Hyeok Kim led the research as the corresponding author.

▲Structure and light-absorption characteristics of a low-voltage, high-sensitivity near-infrared organic photosensor for LiDAR

  In NIR-based sensing systems such as LiDAR, optical sensor technology capable of detecting minute light signals with high sensitivity while operating stably at low voltages is crucial. However, conventional organic phototransistors present limitations such as high driving voltages, low charge mobility, and insufficient NIR absorption characteristics.

  The research team achieved low-voltage operation by using the Y6 organic semiconductor, which exhibits excellent NIR absorption characteristics, and an Al₂O₃ insulating layer with a high dielectric constant. Additionally, they reduced interfacial defects while enhancing the molecular alignment and crystallinity of Y6 by adopting an ODPA  self-assembled monolayer. Consequently, they developed a highly sensitive bipolar organic phototransistor capable of stable NIR detection at voltages of ±5 V or less.

▲Photoresponse characteristics of a low-voltage, high-sensitivity near-infrared organic phototransistor

  Crucially, the research team successfully demonstrated real-time detection of dynamic NIR signals using the developed phototransistor. They confirmed that the device can reliably detect dynamically changing NIR by recording current-signal fluctuations when an NIR laser was repeatedly modulated by finger movements.

  These characteristics demonstrate the potential for future applications in next-generation near-infrared sensing systems, such as LiDAR, noncontact motion sensors, and wearable optical sensors.

▲Demonstration of real-time near-infrared signal detection for LiDAR applications

  Professor Hyeok Kim stated, “This research is significant in that it simultaneously achieves low operating voltages—thus enabling ultra-low-power continuous operation—and highly sensitive NIR detection, thereby increasing the practical feasibility of next-generation optical sensors.” He added, “We expect it to be utilized in various intelligent sensing fields applicable to physical artificial intelligence, such as LiDAR, noncontact sensors, and wearable electronics for humanoids.”

  This research was conducted with support from the Ministry of Science and ICT, the National Research Foundation of Korea’s Mid-Career Researcher Support Program, the Global Basic Research Laboratory (Advanced Track), the Ministry of Trade, Industry, and Resources, and the Korea Planning & Evaluation Institute of Industrial Technology (KEIT)’s “Development of Cutting-Edge Technologies for the Semiconductor Advanced Strategic Industry” project, along with infrastructure support from the University of Seoul’s Semiconductor Research Center (UOS Fab).

▲From left: Researcher Hwapyeong Noh (co-first author), Research Professor Swarup Biswas (co-first author), Professor Yongju Lee (co-author), and Professor Hyeok Kim (corresponding author)