Review
Chemistry, Physical
Chenfang Sun, Xue Wang, Muhammad Aminu Auwalu, Shanshan Cheng, Wenping Hu
Summary: Organic thin film transistors (OTFTs)-based biosensors are capable of transferring biological signals into electrical signals, but developing sensors with excellent sensitivity, selectivity, and stability remains a challenge. Recent research has focused on various types of OTFTs, such as organic field-effect transistors (OFETs), electrolyte-gated OFETs (EGOFETs), and organic electrochemical transistors (OECTs), for high-performance bioelectronics applications.
Article
Nanoscience & Nanotechnology
Rosemary R. Cranston, Mario C. Vebber, Jonatas Faleiro Berbigier, Nicole A. Rice, Claire Tonnele, Zachary J. Comeau, Nicholas T. Boileau, Jaclyn L. Brusso, Adam J. Shuhendler, Frederic Castet, Luca Muccioli, Timothy L. Kelly, Benoit H. Lessard
Summary: This study investigated eight axially substituted SiPcs and their application in solution-processed n-type OTFTs. It was found that the length of the alkyl chain affects device performance and thin-film morphology, and the effects of high-temperature annealing and spin coating time on film formation were explored. The study also revealed that thermal annealing and spin time significantly impact film crystallinity, morphology, and device performance, with bis(tri-n-butylsilyl oxide) SiPc showing the highest electron field-effect mobility among the studied materials.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Multidisciplinary
Zeno Schumacher, Rasa Rejali, Megan Cowie, Andreas Spielhofer, Yoichi Miyahara, Peter Grutter
Summary: Inducing an inversion layer in organic semiconductors is a critical achievement for producing OFET devices, and a new pulsed bias technique is developed to characterize the dopant type of different organic material systems. This technique accurately identifies n-doping in pentacene/PTCDI heterostructure, demonstrating that nanometer-scale lateral extent and thickness are sufficient for an OFET device to operate in the inversion regime.
Article
Engineering, Electrical & Electronic
Meng Zhang, Zhendong Jiang, Sunbin Deng, Zhiying Chen, Xiaotong Ma, Ching-Ho Tien, Lung-Chien Chen, Man Wong, Hoi-Sing Kwok
Summary: The reliability of InSnZnO thin-film transistors (TFTs) under hot carrier (HC) stress is systematically studied in this letter. For the first time, HC degradation accompanied by recovery is observed in InSnZnO TFTs. The joint effects of acceptor-like trap state generation and electron trapping into gate insulator (GI) cause device degradation, while electron detrapping from GI and hole injection into GI contribute to device recovery. The weakening of HC effect with stress time and the vertical electric field enhancement together trigger the dominance of the recovery effect.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Yang-Hao Hung, Ting-Chang Chang, Yu-Fa Tu, I-Nien Lu, Yu-Zhe Zheng, Cheng-Ling Chiang, Jian-Jie Chen, Chuan-Wei Kuo, Li-Chuan Sun, Kuan-Ju Zhou
Summary: A terminal via structure is proposed to improve the drain-induced barrier lowering (DIBL) effect and reliability of half-Corbino organic thin-film transistors (OTFTs). The traditional structure experiences sub-channel conduction and breakdown at high drain voltages, which is inhibited by the terminal via structure.
IEEE ELECTRON DEVICE LETTERS
(2022)
Review
Chemistry, Physical
Chenfang Sun, Tie Wang
Summary: The early determination of disease-related biomarkers can improve patient survival rate significantly. Therefore, explorations for new diagnosis technologies, such as optical and electrochemical methods, have been devoted to life and health monitoring. Organic thin-film transistor (OTFT), as a label-free, low-cost, facial, and rapid detection technology, has attracted significant attention. However, the reliability and accuracy of the biosensor need to be improved while ensuring sensitivity, selectivity, and stability.
Article
Materials Science, Multidisciplinary
Ping Ren, Runqiao Song, Yong Zhu, Brendan O'Connor, Jingyan Dong
Summary: The demand for cost-effective fabrication of printed flexible transistors has increased due to the need for flexible interface devices like e-skins, wearables, and medical patches. This study develops electrohydrodynamic printing processes to fabricate all components of polymer-based organic thin film transistors, streamlining the fabrication procedure. The fully EHD-printed OTFTs show good electrical performance and great mechanical flexibility, providing a cost-effective route for flexible electronics.
ADVANCED MATERIALS TECHNOLOGIES
(2023)
Article
Chemistry, Multidisciplinary
Zachary J. Comeau, Nicole A. Rice, Cory S. Harris, Adam J. Shuhendler, Benoit H. Lessard
Summary: This study investigates the relationship between thin-films of phthalocyanines (Pcs) with various substituents and their response to the cannabinoid Delta(9)-tetrahydrocannabinol (THC) through organic thin-film transistor (OTFT) performance. The findings indicate that the morphology of semiconductor thin-films in Pc-based OTFT sensors can change significantly in the presence of analytes, driven by analyte-Pc coordination and film restructuring.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Review
Chemistry, Physical
Marco Roberto Cavallari, Loren Mora Pastrana, Carlos Daniel Flecha Sosa, Alejandra Maria Rodriguez Marquina, Jose Enrique Eirez Izquierdo, Fernando Josepetti Fonseca, Cleber Alexandre de Amorim, Leonardo Giordano Paterno, Ioannis Kymissis
Summary: Organic thin-film transistors (OTFTs) as gas sensor devices have shown remarkable performance in detecting important target analytes, with electronic properties modulated by molecular engineering. This manuscript provides a comprehensive review on the working principle of OTFTs for gas sensing, including device fabrication methods and recent applications of main organic semiconductors, alongside an outlook toward the future of this exciting technology.
Article
Polymer Science
Zhengran He, Ziyang Zhang, Kyeiwaa Asare-Yeboah, Sheng Bi, Jihua Chen, Dawen Li
Summary: This study demonstrated the use of a metal-containing semicrystalline polymer as an additive to mediate the thin film morphology of solution-grown, small-molecule organic semiconductors, resulting in improved performance of organic thin film transistors.
Article
Physics, Applied
Sanjoy Jena, Debdutta Ray
Summary: The study investigates the combined effect of deposition rate and substrate temperature on the film properties of pentacene, showing that the channel mobility in polycrystalline pentacene thin-film transistors is relatively unaffected by substrate temperature and offers good hole mobility at high growth rates. The surface morphology is characterized using atomic force microscopy, while crystallinity is studied through x-ray diffraction, with a focus on the impact of growth parameters on the crystalline phases of pentacene and their correlation to charge carrier transport. The dispersion of the density of states is influenced by the presence of multiple phases in the path of charge carrier flow.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Chemistry, Physical
Dengming Yao, Xin Xiong, Xiao Fu, Zhuohui Xu, Honglong Ning, Dongxiang Luo, Huansong Tang, Hua Zheng, Rihui Yao, Junbiao Peng
Summary: This study prepared Zr-Al co-doped indium oxide thin films and TFTs using the solution method, and evaluated the film quality through microwave photoconductivity decay. It was found that doping Zr-Al can effectively reduce defects in indium oxide thin films.
SURFACES AND INTERFACES
(2021)
Article
Optics
Laraib S. Khanzada, Muhammad Atif Makhdoom, Xianzhong Lin, Hamed Azimi, Christoph J. Brabec
Summary: This work investigates the charge transport mechanism and dynamics of photocurrent generation in thin films of CZTS nanocrystals. A liquid phase processing route using a molecular-based precursor solution is adopted for in-situ development of CZTS crystals. The results reveal that charge carriers follow band conduction and nearest-neighbor hopping mechanisms at elevated temperatures, while Mott variable-range hopping is dominant at low temperatures, similar to expensive vacuum-deposited kieserite thin films behavior.
Article
Materials Science, Multidisciplinary
Aristeidis Nikolaou, Jakob Leise, Ute Zschieschang, Hagen Klauk, Thomas Gneiting, Ghader Darbandy, Benjamin Iniguez, Alexander Kloes
Summary: A compact model based on charge is proposed in this paper to predict the bias-dependent low-frequency noise in organic thin-film transistors. The model combines the carrier-number fluctuation effect and the fluctuation of the carrier mobility according to the Hooge model to predict the drain-current noise. The model has been verified using experimental data from a large number of organic transistors with two different channel lengths fabricated in the inverted staggered device architecture on a flexible polymeric substrate.
ORGANIC ELECTRONICS
(2023)
Article
Nanoscience & Nanotechnology
Eva Bestelink, Olivier de Sagazan, Lea Motte, Radu A. Sporea
Summary: This study demonstrates that contact-controlled devices exhibit robust performance under extreme biasing conditions, while the multimodal transistor (MMT) provides further control by independently regulating current flow and magnitude. Through technology computer-aided design simulations, the internal electric field distributions are studied and operational guidelines are formulated for optimal characteristics of the MMT. These universal principles should inform device design and operation in all high carrier mobility material systems.
ADVANCED ELECTRONIC MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Chang-Hyun Kim
Summary: This study provides a comprehensive insight into the phenomenon of ambient doping in organic rectifying diodes (ORDs), revealing its impact on multiple device locations and operating modes. Through detailed analysis, critical charge-injection, transport, and doping parameters are extracted, and a validated circuit model is established.
Article
Chemistry, Multidisciplinary
Seyed Mehdi Sattari-Esfahlan, Yvan Bonnassieux, Ioannis Kymissis, Chang-Hyun Kim
Summary: This study demonstrates a high-performance resistive-switching memory cell based on biomass-derived nanoporous graphene (NPG) materials. A new processing method is used to create 3D NPG from Saccharum officinarum, revealing the oxygen ion migration and charge-injection modulation as the key mechanism.
ADVANCED MATERIALS INTERFACES
(2022)
Article
Energy & Fuels
Hyuna Lee, Aniket Rana, Ioannis Kymissis, Chang-Hyun Kim
Summary: This article provides a new insight into the charge-carrier mobility in perovskite solar cells using experimentally calibrated numerical simulations. It is found that increasing the mobility substantially improves the short-circuit current, but simultaneously decreases the open-circuit voltage, resulting in efficiency roll-off in the high-mobility regime. The increased bending of potential profiles and decreased electric field due to carrier diffusion are identified as the key mechanisms behind this behavior, providing a theoretical guideline for material and device engineering.
Article
Multidisciplinary Sciences
Junhwan Choi, Changhyeon Lee, Chungryeol Lee, Hongkeun Park, Seung Min Lee, Chang-Hyun Kim, Hocheon Yoo, Sung Gap Im
Summary: Researchers have developed a multi-valued logic circuit based on heterojunction transistors, which utilizes nonvolatile floating-gate flash memory to control channel conductance and achieve stable operation of ternary logic inverters. The 3D inverters, fabricated in a vertically stacked form, demonstrate high-density integration and device uniformity. The organic flash memory exhibits long retention characteristics, ensuring long-term stability of the 3D inverters. This study provides valuable insights for achieving high-performance multi-valued logic circuits.
NATURE COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
Krunoslav Romanjek, Micael Charbonneau, Chang-Hyun Kim
Summary: This paper applies a robust self-consistent parameter extraction method to study high-performance p-type printed polymer field-effect transistors. Contact resistance and intrinsic channel mobility are simultaneously extracted using an analytically reinforced transmission-line method, allowing for full gate-voltage dependence. The results show a minimum width-normalized contact resistance of 12 kΩcm and a maximum hole mobility of 1.9 cm^2V-1s-1. Additionally, the gate-voltage-dependent mobility is explained within the framework of trap-and-release transport through double-exponential density of states, revealing a low disorder energy of 29 meV near the transport orbital.
FLEXIBLE AND PRINTED ELECTRONICS
(2022)
Article
Nanoscience & Nanotechnology
Hyuna Lee, Yeo Eun Kim, Jisuk Bae, Sungyeop Jung, Radu A. Sporea, Chang-Hyun Kim
Summary: We successfully fabricated high-performance organic source-gated transistors using a critical junction formed between indium-tin oxide and diketopyrrolopyrrole polymer. The partially blocked hole-injection interface offers sufficient drain currents and a strong depletion effect, enabling source pinch-off. Our transistors exhibit outstanding metrics, including an intrinsic gain of 160 V/V, an output resistance of 4.6 G Omega, and a saturation coefficient of 0.2 at 5 V. Drift-diffusion simulation reproduces and rationalizes the experimental data, revealing that the effective contact length is significantly reduced in an interdigitated electrode geometry, leading to low-voltage saturation.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Engineering, Electrical & Electronic
Youngmin Han, Seongjae Kim, Chang-Hyun Kim, Hocheon Yoo
Summary: In this study, the effect of a small molecule contact charge injection layer on thin-film transistors (TFTs) was investigated through experimental results and theoretical calculations. It was found that inserting dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) as a charge injection layer can improve the limited electrical characteristics of C8-BTBT TFT. The results of energy structural simulations confirmed the improved contact properties through the DNTT charge injection layer. Furthermore, the effect of the DNTT charge injection layer on the circuit level was verified through improved noise margin characteristics in a complementary inverter.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Hayoung Kim, Amos A. Boampong, Chang-Hyun Kim, Min-Hoi Kim
Summary: This study demonstrates an effective electrical erasing operation in charge-trap memory (CTM) based on wide bandgap (WBG) semiconductors by introducing an electric flux-modulating counter electrode. The limitations of gate-bias erasing operation in WBG CTMs are overcome by utilizing a top Al metal electrode on the bottom-gate top-contact thin-film transistor memories. The proposed concept of electric flux-modulating counter electrode improves the applicability of WBG semiconductors in future memory technologies.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Physics, Multidisciplinary
Saurabh Sureda Joshi, Kyung-Geun Lim, Chang-Hyun Kim
Summary: This article proposes a new analytical description method for the current-voltage characteristics of vertical OPBTs. The functional model, based on a geometrical parametrization scheme and an equivalent-circuit approach, provides decoupling of the field effect and bulk charge-transport properties. Experimental data validation and predictive capabilities of the model are demonstrated, making it a practical tool for designing and optimizing next-generation OPBTs.
JOURNAL OF THE KOREAN PHYSICAL SOCIETY
(2023)
Article
Materials Science, Multidisciplinary
Youngmin Han, Chang-Hyun Kim, Hocheon Yoo
Summary: In this study, the charge transport behavior in a heterojunction bi-channel composed of two small-molecule p-type-to-p-type semiconductors was investigated. The study found that the channel length had an impact on the characteristics of the bi-channel transistor, and different source operating electrodes affected the threshold voltage and mobility. In addition, the temperature dependence and light-responsivity of the transistor were analyzed, and finite element simulation was used to verify the experimental results.
ORGANIC ELECTRONICS
(2023)
Article
Materials Science, Multidisciplinary
Joon Hyung Park, Ye Ji Shin, Ioannis Kymissis, Yongmin Jeon, Chang-Hyun Kim
Summary: We show the frequency-triggered internal circuit transition in high-performance organic light-emitting diodes. Blue fluorescent light-emitting devices are made using a stable and efficient host-dopant material system. Broad-band impedance spectroscopy analysis reveals two abrupt spectral transitions occurring at two small-signal frequency ranges in these diodes. By fitting Nyquist plots recorded under a wide range of conditions to an equivalent circuit model, we identify the key interface and bulk parameters. The sharp increases in conductance identified from this analysis are conceptually linked to trap deactivation at specific cut-off frequencies, suggesting possibilities for AC applications of organic light-emitting diodes.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Materials Science, Multidisciplinary
Hyuna Lee, Kyung-Geun Lim, Chang-Hyun Kim
Summary: Vertical transistors are essential for future electronics with high density, low power, and high speed. However, there is limited understanding of these unconventional devices, leading to a lack of design rules. This article explores the physical and electrical mechanisms of vertical organic permeable-base transistors, revealing their unique structural features and shedding light on the origin of base-induced current saturation. Predictive simulations based on these insights provide a foundation for theoretically guided materials and device engineering.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Engineering, Electrical & Electronic
Seongjae Kim, Subin Lee, Chang-Hyun Kim, Hocheon Yoo
Summary: This paper proposes the use of a bridge transistor to achieve early saturation characteristics of drain current and investigates the impact of different materials used as bridge layers on the electrical properties of the transistor. The experimental results reveal that bridge transistors with a Schottky junction exhibit early saturation characteristics, which can be attributed to the additional contact resistance and depletion region.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Chang-Hyun Kim
Summary: This article provides an understanding of the emerging high-performance organic heterojunction transistors, evaluates their current status, and discusses future engineering challenges and opportunities.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Review
Materials Science, Multidisciplinary
Yutaka Wakayama, Chang-Hyun Kim, Debdatta Panigrahi, Ryoma Hayakawa
Summary: This paper reviews recent progress in antiambipolar transistor (AAT) development, with a focus on the advantages of organic semiconductors (OSCs) as AAT channels and discusses the carrier transport mechanism and AAT applications.
MATERIALS ADVANCES
(2022)
