Ultralow contact resistance in organic transistors via orbital hybridization

Ultralow contact resistance in organic transistors via orbital hybridization

Nature Communications 14, 324 (2023)

Junpeng Zeng, Daowei He, Jingsi Qiao, Yating Li, Li Sun, Weisheng Li, Jiacheng Xie, Si Gao, Lijia Pan, Peng Wang, Yong Xu, Yun Li, Hao Qiu, Yi Shi, Jian-Bin Xu, Wei Ji & Xinran Wang

Organic field-effect transistors (OFETs) are of interest in unconventional form of electronics. However, high-performance OFETs are currently contact-limited, which represent a major challenge toward operation in the gigahertz regime. Here, we realize ultralow total contact resistance (Rc) down to 14.0 Ω ∙ cm in C10-DNTT OFETs by using transferred platinum (Pt) as contact. We observe evidence of Pt-catalyzed dehydrogenation of side alkyl chains which effectively reduces the metal-semiconductor van der Waals gap and promotes orbital hybridization. We report the ultrahigh performance OFETs, including hole mobility of 18 cm2 V−1 s−1, saturation current of 28.8 μA/μm, subthreshold swing of 60 mV/dec, and intrinsic cutoff frequency of 0.36 GHz. We further develop resist-free transfer and patterning strategies to fabricate large-area OFET arrays, showing 100% yield and excellent variability in the transistor metrics. As alkyl chains widely exist in conjugated molecules and polymers, our strategy can potentially enhance the performance of a broad range of organic optoelectronic devices.

Atom electronics in single-molecule transistors: single-atom access and manipulation

Atom electronics in single-molecule transistors: single-atom access and manipulation

ADVANCES IN PHYSICS: X 8, 2165148 (2023)

The aim of atom electronics, i.e. the final scale of electronics, is to make use of specific individual atoms as active electronic components. Here, we review recent researches on atom electronics in single-molecule transistors (SMTs) through single-atom access and manipulation. We begin by describing the basic concepts and characteristics of atom electronics in SMTs, before discussing some of the most recent examples, including atomic transistors and atomic storage. In our concluding remarks, we discuss some perspectives on fabrication, integration, and other potential atomic devices in which high precision access to, and manipulation of single atoms could be of great significance. This will affect integrated circuits, quantum computing, and other devices that will drive the electronics of the future.

DOI: 10.1080/23746149.2023.2165148

Metal Halides for High-Capacity Energy Storage

Metal Halides for High-Capacity Energy Storage

Small, DOI: 10.1002/smll.202205071

Hui Ma, Xusheng Wang, Cong Wang, Huanrong Zhang, Xinlei Ma, Wenjun Deng, Ruoqi Chen, Tianqi Cao, Yuqiao Chai, Yonglin He, Wei Ji, Rui Li, Jitao Chen, Junhui Ji, Wei Rao, Mianqi Xue

Abstract: High-capacity electrochemical energy storage systems are more urgently needed than ever before with the rapid development of electric vehicles and the smart grid. The most efficient way to increase capacity is to develop electrode materials with low molecular weights. The low-cost metal halides are theoretically ideal cathode materials due to their advantages of high capacity and redox potential. However, their cubic structure and large energy barrier for deionization impede their rechargeability. Here, the reversibility of potassium halides, lithium halides, sodium halides, and zinc halides is achieved through decreasing their dimensionality by the strong π–cation interactions between metal cations and reduced graphene oxide (rGO). Especially, the energy densities of KI-, KBr-, and KCl-based materials are 722.2, 635.0, and 739.4 Wh kg−1, respectively, which are higher than those of other cathode materials for potassium-ion batteries. In addition, the full-cell with 2D KI/rGO as cathode and graphite as anode demonstrates a lifespan of over 150 cycles with a considerable capacity retention of 57.5%. The metal halides-based electrode materials possess promising application prospects and are worthy of more in-depth researches.

DOI: 10.1002/smll.202205071

Improving the band alignment at PtSe2 grain boundaries with selective adsorption of TCNQ

Improving the band alignment at PtSe2 grain boundaries with selective adsorption of TCNQ

Nano Research 16, 3358-3363 (2023)

Yanhui Hou#, Ziqiang Xu#, Yan Shao, Linlu Wu, Zhongliu Liu, Genyu Hu, Wei Ji, Jingsi Qiao*, Xu Wu*, Hong-Jun Gao & Yeliang Wang*

Grain boundaries in two-dimensional (2D) semiconductors generally induce distorted band alignment and interfacial charge, which impair their electronic properties for device applications. Here, we report the improvement of band alignment at the grain boundaries of PtSe2, a 2D semiconductor, with selective adsorption of a presentative organic acceptor, tetracyanoquinodimethane (TCNQ). TCNQ molecules show selective adsorption at the PtSe2 grain boundary with strong interfacial charge. The adsorption of TCNQ distinctly improves the band alignment at the PtSe2 grain boundaries. With the charge transfer between the grain boundary and TCNQ, the local charge is inhibited, and the band bending at the grain boundary is suppressed, as revealed by the scanning tunneling microscopy and spectroscopy (STM/S) results. Our finding provides an effective method for the advancement of the band alignment at the grain boundary by functional molecules, improving the electronic properties of 2D semiconductors for their future applications.

DOI:10.1007/s12274-022-5009-8

2022 Renmin Internal Symposium on Low-D Physics

2022 Renmin Internal Symposium on Low-D Physics

2022年9月3日,中国人民大学物理学系低维和表界面物理相关的研究组举办了首届内部学术交流会。来自蔡鹏、程志海、陈珊珊、季威、刘灿、刘易和王善才等7个研究组的12位报告人,20余位线下参与人和近30位线上参与人进行了充分讨论与交流。会议期间,7个研究组的负责人协商约定,交流会每年一次,轮流组织,仅限内部交流,报告内容不照相、不泄露。

Symposium photo for on-site participants