Article
Physics, Condensed Matter
K. Chakraborty, A. Das, R. Mandal, D. K. Mandal
Summary: This research investigates the physics of natural organic semiconductor-based single-layer devices at low voltage using theoretical models and simulation techniques, demonstrating high consistency with the theoretical explanations. Experimental validation confirms trap-assisted conduction and the exponential decay of the ideality factor at low voltage.
SOLID STATE COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Daniel Splith, Stefan Mueller, Holger von Wenckstern, Marius Grundmann
Summary: A comprehensive model is presented for calculating the entire IV characteristics of Schottky contacts, allowing detailed analysis of empirical fit parameters like the ideality factor. The model considers variations in semiconductor net doping density and barrier height inhomogeneities, requiring input parameters such as doping profile and barrier height distribution. Measuring conditions impact IV characteristics, with sweep parameters included in the model for understanding charging currents and voltage shifts.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Youkyung Seo, Inyeob Na, Yeeun Kim, Heeyoung Chae, Kilhwan Oh, Joonyoung Yang, Sooyoung Yoon, Min-Kyu Joo
Summary: A simple and effective methodology is proposed to determine the contact resistance (RCT) and characteristic trap energy (ET) of OLEDs simultaneously, showing high feasibility and accuracy. The method was applied to study the degradation mechanism of a blue OLED, revealing different degradation patterns of the metal-to-transport layer interface and emission layer.
ORGANIC ELECTRONICS
(2021)
Article
Chemistry, Multidisciplinary
Sohyeon Kim, Jun Hyeok Jang, Ziang Wu, Mi Jung Lee, Han Young Woo, Inchan Hwang
Summary: The study investigates the correlation of n(id), PL characteristics, and V-oc in triple-cation mixed-halide perovskite depending on interfacial crystal quality. It highlights the importance of evaluating interfacial crystal quality for understanding charge recombination and device optimization.
Article
Astronomy & Astrophysics
R. A. Jackson, G. Martin, S. Kaviraj, M. Ramsoy, J. E. G. Devriendt, T. Sedgwick, C. Laigle, H. Choi, R. S. Beckmann, M. Volonteri, Y. Dubois, C. Pichon, S. K. Yi, A. Slyz, K. Kraljic, T. Kimm, S. Peirani, I Baldry
Summary: Low-surface-brightness galaxies (LSBGs) make up the majority of galaxies in the dwarf regime with smaller stellar masses. Using the high-resolution cosmological simulation NewHorizon, the study explains the origin of LSBGs and the large observed spread in surface brightness within galaxies of similar stellar masses.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Materials Science, Multidisciplinary
Shuaibing Li, Weidong Sun, Xiaofang Li, Xiaoyang Xia, Liang Zhou
Summary: By constructing a gradient-doping sensitization system and doping europium complex into the light-emitting layer, this study has achieved low operation voltage white OLEDs with excellent color stability. The gradient-doping sensitization system allows precise control of carriers' distribution and recombination zone in different EMLs, resulting in low turn-on voltage and negligible chromaticity coordinates variation. Furthermore, the obtained white OLED exhibits high brightness, current efficiency, power efficiency, and external quantum efficiency.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Qi Wei, Ruihong Duan, Qi Zhang, Linghai Xie, Ruidong Xia, Yuanping Yi, Jeremie Leonard, Stefan Haacke, Juan Cabanillas-Gonzalez, Yan Qian, Wei Huang
Summary: By designing compounds with tunable electronic transition characters and studying their vibrational modes using computational calculations and experiments, this study provides guidelines for the rational design of efficient organic laser materials. The results show that the coupling of high wavenumber vibrational modes to pure LE states is essential for optical gain, while broad excited-state absorption overwhelming stimulated emission is favored when HLCT or CT states are coupled to low frequency vibrational modes.
ADVANCED OPTICAL MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Heqing Ye, Hyeok-jin Kwon, Su Cheol Shin, Hwi-young Lee, Young Ho Park, Xiaowu Tang, Ruxian Wang, Kanghyuck Lee, Jisu Hong, Zhijun Li, Wonkyo Jeong, Jiyeong Kim, Chan Eon Park, Jihoon Lee, Tae Kyu An, Insik In, Se Hyun Kim
Summary: This study demonstrates a novel strategy to induce high-k characteristics with durable polysilsesquioxane (PSQ)-based dielectrics, paving the way for the production of practical and printable high-k dielectrics for low-voltage-operating high-performance organic field-effect transistors (OFETs). Different PSQs exhibit distinct polarization phenomena, leading to different hysteresis behaviors during device operation.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Physical
M. Sunkur, C. Aytug-Ava, O. Gullu
Summary: The present study investigates the effect of erythrosine B (ERY) organic material as an interface layer on the electronic characteristics of the Al/p-Si junction. Characterization techniques such as AFM, NMR, UV-Vis, and FTIR were utilized to analyze the ERY dye molecule. The results showed that the presence of the ERY film led to coated nanoparticles on the substrate surface.
SURFACES AND INTERFACES
(2023)
Review
Engineering, Electrical & Electronic
Jordan R. Nicholls
Summary: SiC devices exhibit detrimental second order effects caused by electrically active traps, impacting the performance of Schottky diodes. Understanding and studying these traps is crucial for improving diode performance and device/circuit modeling.
MICROELECTRONICS RELIABILITY
(2021)
Article
Energy & Fuels
Gaia M. N. Javier, Priya Dwivedi, Yoann Buratti, Ivan Perez-Wurfl, Thorsten Trupke, Ziv Hameiri
Summary: This study evaluates and enhances the accuracy of commonly used expressions for the fill factor (FF), and investigates parameters that can affect the accuracy of the revised expressions. The empirical coefficients of the commonly used analytical expressions are recalculated using a modified fitting approach. While the predictions of the revised expressions match the results of theoretical simulations, discrepancies are observed when compared to actual measurements. The study explores the different impacts of unaccounted factors in the expressions, and suggests adjusting the ideality factor or considering edge recombination to improve the accuracy of predictions. Additionally, the expressions may slightly overestimate the FF of cells with non-uniform implied open-circuit voltage distribution. The findings of this study can be helpful in developing techniques for extracting FF from luminescence images of industrial solar cells as electrical parameter extraction methods from such images continue to improve.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Article
Materials Science, Multidisciplinary
Kahtan Adnan Hussain, Ghusoon M. Ali, Aimen Boubaker, Adel Kalboussi
Summary: Planar organic Schottky diodes were fabricated using undoped pentacene as an active layer with both palladium and aluminum as contacts. The pentacene films exhibited various orientations as observed through X-ray diffraction measurements. The diode parameters were analyzed using thermionic emission theory, showing a decreasing ideality factor and increasing barrier height with increasing temperature. The device deposited on the n-Si <111> substrate showed larger forward and lower reverse currents than the n-Si <100> substrate device.
Article
Chemistry, Multidisciplinary
Wei Chen, Diana Dahliah, Gian-Marco Rignanese, Geoffroy Hautier
Summary: The study examines the controversial role of cation disorder in the low open-circuit voltage of CZTS kesterite absorber. It suggests that extensive disorder stabilizes the formation of Sn-Zn antisite, contributing to the V-OC deficit. The methodology presented in this work offers insight into optimizing kesterite solar devices for higher efficiency.
ENERGY & ENVIRONMENTAL SCIENCE
(2021)
Article
Chemistry, Physical
Zhongbin Wu, Yuan Liu, Erjuan Guo, Ghader Darbandy, Shu-Jen Wang, Rene Huebner, Alexander Kloes, Hans Kleemann, Karl Leo
Summary: This study demonstrated organic permeable base light-emitting transistors, which are three-terminal vertical optoelectronic devices operating at driving voltages below 5.0 V, emitting in the red, green, and blue ranges, and achieving peak external quantum efficiencies of 19.6%, 24.6%, and 11.8%, respectively. The key to the good performance obtained is the nano-pore permeable base electrode located at the center of the device, which forms a distinctive optical microcavity and regulates charge carrier injection and transport. This work paves the way towards efficient and low-voltage organic light-emitting transistors, beneficial for power-efficient active matrix displays and solid-state lighting.
Review
Materials Science, Multidisciplinary
Markus Clark Scharber, Niyazi Serdar Sariciftci
Summary: Important parameters of an organic semiconductor material include the electronic band gap and the positions of the highest occupied and lowest unoccupied bands relative to vacuum. The ability to tune these parameters through molecular chemical design is a key advantage of semiconducting polymers. Low band gap polymers play a crucial role in optoelectronic applications.
ADVANCED MATERIALS TECHNOLOGIES
(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
Nanoscience & Nanotechnology
Galyna Sych, Patrice Rannou, Maxime Jullien-Palletier, Said Sadki, Yvan Bonnassieux, Sebastien Sanaur
Summary: This study explores low-dimension organic electrochemical transistors (OECTs) and highlights the importance of optimizing micro-fabrication technologies to improve their performance. By decreasing the contact overlap length, the contact resistance can be reduced, leading to faster switching speed and improved circuit design for OECT-based integrated circuits.
ADVANCED ELECTRONIC MATERIALS
(2023)
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
Biology
Mihaly Voeroeslakos, Omid Yaghmazadeh, Leeor Alon, Daniel K. Sodickson, Gyoergy Buzsaki
Summary: In recent years, the exposure to radiofrequency (RF) fields has been increasing due to the rapid development of wireless and medical imaging technologies. This study investigated the neurological effects of RF exposure in rodents with implanted neuronal recording electrodes. The study found that RF exposure could induce fast onset firing of single neurons without causing heat injury, and brain implants amplified the effect of RF stimulation, resulting in reversible behavioral changes. The study also revealed a significant increase in brain temperature in the vicinity of the implant.
BIOELECTROMAGNETICS
(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)
