Pohang University of Science and Technology · Engineering
Professor Minjun Kim's research lab specializes in the molecular design and synthesis of advanced organic semiconductors for next-generation optoelectronic devices. The lab focuses on developing donor–acceptor polymers and small molecules with tailored electronic and structural properties to achieve high charge carrier mobility, balanced ambipolar transport, and efficient near-infrared emission. Key research directions include the rational design of n-type semiconducting polymers—particularly naphthalene diimide (NDI)-based materials—for use in flexible, all-polymer solar cells and field-effect transistors, with an emphasis on controlling morphology and enhancing interfacial connectivity to improve device performance and mechanical stability. The lab also explores fluorination strategies and molecular engineering to overcome the energy-gap law in organic light emitters and to enhance electron transport in conjugated polymers.
Figures are computed from collected data and may differ slightly.
Abstract Polymeric semiconductors have demonstrated great potential in the mass production of low‐cost, lightweight, flexible, and stretchable electronic devices, making them very attractive for commercial applications. Over the past three decades, remarkable progress has been made in donor–acceptor (D–A) polymer‐based field‐effect transistors, with their charge‐carrier mobility exceeding 10 cm 2 V −1 s −1 . Numerous molecular designs of D–A polymers have emerged and evolved along with progress
Abstract Organic light‐emitting materials in the near‐infrared (NIR) region are important to realize next‐generation lightweight and wearable applications in bioimaging, photodynamic therapy, and telecommunications. Inorganic and organometallic light‐emitting materials are expensive and toxic; thus, the development of purely organic light‐emitting materials is essential. However, the development of highly efficient NIR light‐emitting materials made of organic materials is still in its infancy. T
Abstract A molecular design strategy to achieve highly balanced ambipolar charge transport for donor–acceptor (D–A) isoindigo (IIG)‐based copolymer through systematic selection of fluorination positions is reported. To study fluorine substitution site effects on electronic and structural properties, two fluorinated IIG‐based copolymers (PIIG‐iFT2 and PIIG‐oFT2) are synthesized, which contain two fluorine atoms at the bithiophene (T2) inner and outer site and compare them with a nonfluorinated co
Naphthalene diimide (NDI)-based copolymers are promising polymer acceptors in all-polymer solar cells (all-PSCs), but their large crystal domains cause large-scale phase separation in all-polymer blend films. This limits the photovoltaic performance and mechanical stability of all-PSCs. Herein, we control all-polymer blend films by introducing a fluorinated copolymer of NDI and (E)-1,2-bis(3-fluorothiophen-2-yl)ethene (FTVT) (PNDI–FTVT) as a polymer acceptor for flexible all-PSCs. The copolymer
Organic photovoltaics (OPVs) have emerged as a promising next-generation technology with great potential for portable, wearable, and transparent photovoltaic applications. Over the past few decades, remarkable advances have been made in non-fullerene acceptor (NFA)-based OPVs, with their power conversion efficiency exceeding 18%, which is close to the requirements for commercial realization. Novel molecular NFA designs have emerged and evolved in the progress of understanding the physical featur
Naphthalene diimide (NDI)-based conjugated polymers with bithiophene or dithienylethene (TVT) units can form large crystal domains through NDI-driven self-assembly and are widely used in organic electronic devices as n-type materials. However, improving electron transport in these semiconducting polymers has been a significant challenge mainly due to poor electrical connections between the crystal domains. Formation of an interconnected network of small domains with short-range ordering and mixe
Abstract Light‐emitting organic small molecules require high internal and external quantum efficiencies with excellent radiative characteristics for their potential application in next‐generation optoelectronics. Nonetheless, achieving high efficiency in solid states remains a formidable challenge, primarily owing to the non‐radiative processes. Therefore, conformational modulation in solid states is pivotal in influencing emission properties to mitigate non‐radiative decay. Notably, modifying i
The power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) using conjugated polymers (CPs) as hole-transport materials (HTMs) have been drastically enhanced. This is mainly attributed to the development of CPs with high charge mobilities. In PSCs, HTMs play important roles in extracting and transporting photo-generated holes from the perovskite layer. Thus, enhancing both charge transport in the HTM and charge transfer at the HTM/perovskite interface would be more beneficial than
Abstract Crosslinkable additive in organic solar cells has great potential to fix metastable bulk heterojunction, supplying solutions for burn‐in loss and long‐term instability. New roles of crosslinkable additive as a solvent additive, radical scavenger, and stretchability enhancer beyond its well‐known role as a crosslinker with morphology frozen effect are reported. According to the main chain structure between Br in end groups, crosslinkable additive is divided into two types of alkyl and s
Organic photovoltaics (OPVs) are a promising next-generation photovoltaic technology with great potential for wearable and transparent device applications. Over the past decades, remarkable advances in device efficiency close to 20 % have been made for bulk heterojunction (BHJ)-based OPV devices with long-term stability, and room for further improvements still exists. In recent years, ancillary components have been demonstrated as effective in improving the photovoltaic performance of OPVs by co
Abstract The primary challenge in the commercialization of organic photovoltaics (OPVs) is ensuring long‐term stability, making the study of their degradation mechanisms essential. This study is centered on the underlying mechanisms of degradation, providing a systematic and in‐depth analysis of their instability factors. A clear distinction between burn‐in loss and long‐term degradation is established, with a comprehensive examination of the mechanisms governing each process. The review highlig
High thermal stability is crucial for the commercialization of organic solar cells (OSCs). The thermal stability of OSCs has been improved using the tailoring blend morphology of bulk heterojunctions (BHJs). Herein, we demonstrated thermally stable OSCs in a ternary blended system containing low-crystalline semiconducting polymers (<b>asy-PNDI1FTVT</b> and PTB7-Th) and a non-fullerene acceptor (Y6). The asymmetric n-type semiconducting polymer (<b>asy-PNDI1FTVT</b>) differed from general symmetr
We investigate molecular symmetricity on the physical and photoelectric properties of semiconducting polymers by selectively incorporating different numbers of fluorine atoms at different positions in the donor unit of NDI-based copolymers.
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