Фосфорное легирование и управление электрическим полем повысили чувствительность гибких инфракрасных фотодетекторов в пять раз

# Phosphorus (P) Doping and Electric-Field Engineering Boost Photoresponsivity by More Than Fivefold, Enabling a High-Performance Flexible Near-Infrared Photodetector # High Sensitivity and Durability Achieved Without Complex New-Material Development, Paving the Way for Next-Generation Optoelectronic Devices for Wearables, Healthcare, and Optical Communications Newswise — CHANGWON, South Korea — A research team led by Principal Researcher Jung-Dae Kwon, Yonghun Kim, and Jongwon Yoon of the Energy & Environment Materials Research Division at the Korea Institute of Materials Science (KIMS), headed by President Chul-jin Choi, has developed a flexible near-infrared (NIR) photodetector that delivers more than five times higher photoresponsivity while maintaining its performance under repeated bending. The technology is expected to serve as a core platform for next-generation flexible optoelectronic devices, including wearable healthcare devices, medical diagnostic sensors, and optical communication receivers. Near-infrared light is invisible to the human eye but can penetrate skin and biological tissue relatively effectively. This property has enabled its widespread use in applications such as heart-rate and blood-oxygen monitoring in smartwatches, medical diagnostics, night imaging, and optical communications. Demand is also growing for flexible NIR sensors that can conform closely to the skin or curved surfaces. Most NIR sensors currently used in wearable devices, however, rely on rigid silicon photodetectors mounted onto flexible substrates, limiting their suitability for applications involving repeated bending. Flexible photodetectors based on organic semiconductors and quantum dots have been studied as alternatives, but organic semiconductors often suffer from insufficient durability, while quantum dots can exhibit limited environmental stability that leads to performance degradation. To overcome these limitations, the KIMS research team developed a flexible NIR photodetector capable of maintaining high performance even under repeated mechanical deformation. The device employs a heterojunction combining n-type hydrogenated amorphous silicon (n-a-Si), which is compatible with conventional CMOS semiconductor manufacturing processes, and tellurium (Te), which efficiently absorbs near-infrared light. The researchers simultaneously optimized phosphorus doping and the internal electric-field structure of the device, substantially improving its photosensitivity and detection performance while maintaining mechanical durability under repeated bending. The photodetector was fabricated on a flexible colorless polyimide (CPI) substrate by sequentially stacking tellurium, hydrogenated amorphous silicon, a front-surface-field (FSF) layer, and a transparent electrode. Tellurium absorbs near-infrared light and generates charge carriers, while the n-a-Si layer facilitates their transport toward the electrode. The researchers precisely controlled the phosphorus doping concentration in the amorphous silicon to reduce internal defects and improve charge-transport properties. They also introduced an FSF layer between the transparent electrode and the n-a-Si layer. The resulting electric-field structure guides photo-generated carriers more efficiently toward the electrode while suppressing electron–hole recombination, thereby minimizing electrical signal loss. As a result, the developed photodetector achieved approximately a 5.1-fold increase in photoresponsivity and a 2.6-fold increase in detectivity compared with the conventional device structure. It also demonstrated stable light detection across a broad wavelength range from 400 to 1,600 nanometers. The device further retained more than 90% of its initial photoresponsivity after 4,000 bending cycles, demonstrating excellent mechanical durability for flexible-device applications. A key feature of the research is that the team improved photodetection performance not by developing a new light-absorbing material or modifying the photoactive layer itself, but by simultaneously optimizing the material quality of hydrogenated amorphous silicon and the internal electric-field structure of the semiconductor device. This approach can substantially enhance photodetector performance without introducing additional complex fabrication processes, offering advantages in manufacturing cost and commercialization potential. Because the technology is based on inorganic semiconductors compatible with conventional CMOS manufacturing processes, it is also well suited for large-area fabrication. Its ability to maintain high performance and mechanical durability on flexible substrates makes it particularly suitable for skin-mounted sensors and electronic devices integrated onto curved surfaces. The technology is expected to serve as a key platform for a wide range of flexible optoelectronic applications, including wearable healthcare devices, medical diagnostic sensors, optical communication receivers, and image sensors for autonomous vehicles and robots. “This study demonstrates that the performance of flexible near-infrared photodetectors can be significantly improved by simultaneously controlling the microstructure of the semiconductor material and the internal electric field of the device,” said Jung-Dae Kwon, Principal Researcher and project leader at KIMS. “We expect the technology to serve as a core component of wearable optical sensors and next-generation optoelectronic systems. We will continue our research toward a next-generation flexible optoelectronic platform by integrating large-area manufacturing and low-power operation technologies,” he added. The research was supported by the Ministry of Science and ICT through the KIMS Institutional Research Program and the Global TOP Strategic Research Group Program of the National Research Council of Science & Technology (NST), as well as the Energy Technology Development Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Nano and Materials Technology Development Program of the National Research Foundation of Korea (NRF). The findings were published online on July 6, 2026, in Advanced Science (Impact Factor: 14.1), a leading international journal in materials science and energy. The paper is titled “Systematic Phosphorus-Driven Structural and Field Engineering of n-a-Si for Flexible n-a-Si/Te Near-Infrared Photodetectors.” ----------------------------------------------------------------------- ### About Korea Institute of Materials Science(KIMS) KIMS is a non-profit government-funded research institute under the Ministry of Science and ICT of the Republic of Korea. As the only institute specializing in comprehensive materials technologies in Korea, KIMS has contributed to Korean industry by carrying out a wide range of activities related to materials science including R&D, inspection, testing&evaluation, and technology support.