Jaeyong Ahn

All Publications

• High-performance flexible circularly polarized light photodetectors based on chiral n-type naphthalenediimide-bithiophene polymers NPJ FLEXIBLE ELECTRONICS Gao, K., Kim, S., Zhao, W., Ye, X., Wang, P., Liu, L., Ahn, J., Zhuo, H., Li, Z., Wang, Z., Chang, G., Ma, W., Zhang, M., Long, G., Shang, X., Oh, J. 2025; 9 (1)

  View details for DOI 10.1038/s41528-025-00443-2

  View details for Web of Science ID 001546042800001

• Circularly Polarized Light-Responsive Flexible Synapses Based on Supramolecular n-Type Chiral Organic Single Crystal/p-Type Polymer Heterojunctions. ACS nano Kim, B., Ahn, J., Gao, K., Shang, X., Oh, J. H. 2025

  Abstract

  Chiral neuromorphic devices that detect both circularly polarized light and digitized electrical signals are cutting-edge combinations of neuromorphic engineering and chiral optoelectronics that may advance both computing and sensing. In this work, organic electrochemical transistors (OECTs) based on n-type 2D organic single-crystal/p-type polymer heterojunctions are described. The supramolecular characteristics and molecular packing modes of the single crystals endowed the system with a high polarization selectivity. Furthermore, the integration of a p-n heterojunction facilitated modulation of charge trapping and separation at the interface, leading to improved chiroptical sensitivity. The devices emulate key features of biological synapses, including paired-pulse facilitation (PPF) and synaptic plasticity according to number, voltage, and frequency of spikes (SNDP, SVDP, and SFDP) under both electrical and optical stimulation. Leveraging these properties, the biocompatibility and flexibility of these synapse-like devices enabled the development of wearable chiral neuromorphic devices on flexible polyethylene naphthalate (PEN) substrates, highlighting their potential for advanced bioinspired applications such as humanoid robots. Additionally, the artificial nervous system based on a trained convolutional neural network successfully performs image classification work. These findings in chiral single-crystal-based artificial synapses suggest potential strategies for advanced opto-neuromorphic computing depending on the wavelength and circular polarization state.

  View details for DOI 10.1021/acsnano.5c07495

  View details for PubMedID 40719571

• Nearly 50-50 Face-on to Edge-on Crystallites in Regioisomeric Polymers Based on <i>n</i>-Type Thienylvinyl-1,1-dicyanomethylene-3-indanone for High Electron Mobility ACS APPLIED MATERIALS & INTERFACES Lee, S., Lee, S., Jeong, S., Ahn, J., Yang, S., Jeong, S., Cho, Y., Oh, J., Yang, C. 2025; 17 (27): 39366-39374

  Abstract

  To better understand how backbone regioregularity at the molecular level influences the bulk properties of conjugated polymers, we investigated the optical and electrochemical properties, energetics, microstructure, and charge transport characteristics of newly synthesized regioisomeric polymers. These include a regiorandom polymer (PTIC) and two regioregular analogs (PTIC-γ and PTIC-δ). All these polymers exhibit a broad infrared absorption band covering from 300 to 1000 nm, a narrow band gap of 1.25 eV, and a low-lying lowest unoccupied molecular orbital deeper than 3.88 eV. PTIC-γ features weaker chain-to-chain packing owing to its U-shape backbone, whereas PTIC and PTIC-δ present strong aggregation with their wave-like backbone shapes. Initially, all pristine polymer films reveal a bimodal texture dominated by a preferential face-on orientation. Following thermal annealing, the crystallites reorient further into a nearly exclusive face-on packing for PTIC-γ and PTIC-δ films, whereas PTIC films maintain a roughly 50-50 face-on to edge-on orientation ratio. As a result, the best electron mobility, reaching 1.43 × 10-1 cm2 V-1 s-1, is achieved from the annealed PTIC film owing to the construction of a continuous 3D charge-transport pathway.

  View details for DOI 10.1021/acsami.5c05769

  View details for Web of Science ID 001518545200001

  View details for PubMedID 40574321

• Stable Open-Shell Conjugated Terpolymer with Extended NIR Absorption for Organic Photodetectors Detecting Beyond 1000 nm ACS APPLIED MATERIALS & INTERFACES Jeong, M., Lee, S., Won, Y., Ahn, J., Kim, M., Oh, J. 2025: 25591-25601

  Abstract

  Near-infrared (NIR) photodetectors play crucial roles in many scientific, industrial, and medicinal fields. However, conventional organic photodetectors (OPDs) often do not utilize the NIR region due to poor absorption beyond 1000 nm. In this study, an open-shell conjugated terpolymer is synthesized for NIR detection. This polymer contains diketopyrrolopyrrole (DPP), thiophene, and benzo[1,2-c;4,5-c']bis[1,2,5]thiadiazole (BBT); these components form the novel random terpolymer poly{2,5-bis(2-decyltetradecyl)-3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione]-co-thiophene-co-benzo[1,2-c;4,5-c']bis[1,2,5]thiadiazole} (PDPPTBBT) via Stille coupling polymerization. The diradicals generated by the open-shell characteristics of PDPPTBBT become stronger as molecular packing is enhanced. This enhancement enables absorption at wavelengths beyond 1000 nm. PDPPTBBT exhibits temperature-independent Pauli paramagnetic properties. Additionally, electron paramagnetic resonance measurements reveal that compared with the singlet ground state, the polymer exhibits a higher stability in the triplet ground state and a high spin (S = 1). PDPPTBBT can act as an acceptor or a donor in films in which the material is blended with either poly(3-hexylthiophene-2,5-diyl) or Y6. OPDs prepared using the blended films display detection wavelengths exceeding 1000 nm with a maximum external quantum efficiency of 126% at 1050 nm and a specific detectivity (D*) of 7.5 × 1011 Jones.

  View details for DOI 10.1021/acsami.5c03911

  View details for Web of Science ID 001471670600001

  View details for PubMedID 40254972

• Enhancing optoelectronic performance of organic phototransistors through surface doping of tetra-bromo perylene diimide single crystals JOURNAL OF MATERIALS CHEMISTRY C Zhuo, H., Cho, Y., Gao, K., Wang, Z., Li, Z., Chu, X., Cui, T., Choi, W., Chang, G., Ahn, J., Shang, X., Oh, J. 2025; 13 (16): 8077-8083

  View details for DOI 10.1039/d5tc00361j

  View details for Web of Science ID 001448621900001

• Helical donor-acceptor bulk heterojunctions for dissymmetric circularly polarized light detection CHEMICAL ENGINEERING JOURNAL Song, I., Ahn, J., Lee, S., Lee, S., Kim, S., Cho, Y., Oh, J. 2025; 505

  View details for DOI 10.1016/j.cej.2024.158991

  View details for Web of Science ID 001400188200001