A joint research 멤버십토토 led by Professor Jung In-hwan from the Department of Organic and Nano Engineering at Hanyang University and Professor Jeong Dae-sung from the Department of Chemical Engineering at POSTECH (Pohang University of Science and Technology) announced on July 15 the development of a high-performance ultraviolet (UV) organic photodetector (UV-OPD) that combines precise UV selectivity, fast response, and low noise.

This device is characterized by its UV selectivity, rapid response time, low dark current, and high visible light transmittance. The research 멤버십토토 vertically integrated the UV-OPD with conventional silicon-based complementary-metal-oxide-semiconductor (CMOS) photodetectors via vacuum deposition, creating a novel image sensor platform. The device allows users to actively control the detection wavelength range, making it a key enabling technology for next-generation optoelectronic devices, including multifunctional, high-performance image sensors.

UV sensing technology has broad applications in healthcare, environmental monitoring, defense and security, and precision imaging systems. To detect UV light selectively, organic semiconductors with a wide energy bandgap and excellent charge transport properties are required. However, lengthening the conjugated backbone of molecules typically reduces the bandgap and shifts absorption toward longer wavelengths—traits that conflict with UV detection. This has made it a major challenge in the field to develop molecular structures that react selectively to short wavelengths while maintaining good electrical performance.

In addition to overcoming these molecular limitations, the team also introduced a new fabrication approach. While most organic photodetectors have relied on solution processing—valued for its simplicity and cost-effectiveness—it poses challenges for controlling film thickness and interfacial properties. In contrast, vacuum deposition, widely used in the OLED industry, enables precise thin-film formation without toxic solvents, offering better interfacial properties and high process compatibility. However, UV-selective organic photodetectors produced via vacuum deposition are extremely rare, making this study a significant technological breakthrough on both fronts.

The team designed three small-molecule donors—TzB, TzNα, and TzNβ—based on a thiazolothiazole (Tz) heterocyclic core. Each molecule was structurally tailored by modifying the position and type of conjugated substituents to induce differences in crystallinity and molecular alignment. Among them, TzNβ, which incorporates a β-naphthalene ring, achieved enhanced molecular planarity and extended conjugation. This facilitated strong intermolecular π-π stacking and ideal alignment in bulk heterojunction films, thereby improving both UV absorption and charge transport—key factors in boosting device performance.

As a result, the 멤버십토토 fabricated a top-illumination organic photodetector with excellent visible transmittance and successfully integrated it onto a CMOS image sensor through vacuum deposition. By combining a UV-selective organic photodetector with a silicon sensor optimized for visible light on a single platform, they achieved wavelength-separated detection, simplified processing, reduced costs, and improved spatial efficiency.

The study is academically significant for elucidating the quantitative relationship between molecular structure and device performance at the molecular level. Furthermore, it proposes a viable path toward multifunctional image sensor technology, expanding the practical applications of organic optoelectronic devices.

This research was supported by the Ministry of Science and ICT (project: Development of high-performance flexible optical communication systems using integrated vertical transistors and wavelength-matched organic LEDs/photodiodes) and the Ministry of Trade, Industry and Energy (project: Development of thermally stable near-infrared organic emitter/absorber materials and devices for integrated-sensor OLED displays).

The paper, titled “Rational Molecular Design of π-Extended Thiazolothiazole for High-Performance UV-OPDs Seamlessly Integrated with CMOS,” was published online in July 2025 in Advanced Materials, a globally renowned journal in materials science (JCR top 2.2%). Ph.D. candidates Park Jae-hee (Hanyang University) and Pyo Won-jun (POSTECH) served as co-first authors, with Professors Jung In-hwan (Hanyang University) and Jeong Dae-sung (POSTECH) as corresponding authors.