Solution-processed organic field-effect transistors with cross-linked poly(4-vinylphenol)/polyvinyl alcohol bilayer dielectrics

Zhang

et al. 2021

Self Cite

The optoelectronic characteristics of organic–inorganic perovskites can be tailored by mixing different metal cations with various ratios. 2D layered organic–inorganic perovskites with charge transport anisotropy are considered as promising channel materials for field‐effect transistors. However, there are few reports about 2D Pb‐based perovskite thin film transistors although their Sn counterparts have been extensively investigated for use in this field. Herein, the synthesis and tuning of the physical properties of 2D layered Sn–Pb perovskite solid solutions based on phenylethylammonium tin and lead iodide perovskites ((PEA)2SnxPb1−xI4 (x = 0, 0.3, 0.5, 0.7, 1)) are reported. A thermally activated semiconducting behavior is confirmed in this series of perovskite thin films. The electronic band structure, conductivity, and in‐plane ion migration are found to be largely affected by the Sn–Pb ratio, which is important for transistor performance. Furthermore, the 2D layered mixed Sn–Pb perovskite field‐effect transistors constructed on cheap and commercially available polymer dielectrics and a signature of field‐effect characteristics in the (PEA)2PbI4 film are demonstrated for the first time. The (PEA)2Sn0.7Pb0.3I4 transistor operating at room temperature in air exhibits a hole mobility of 0.02 cm2 V−1 s−1. This work can improve the understanding of the influence mechanisms of ion migration in 2D layered perovskite field‐effect transistors.

Section: Resultsmentioning

confidence: 99%

Charge Transport in 2D Layered Mixed Sn–Pb Perovskite Thin Films for Field‐Effect Transistors

Zhang

et al. 2021

Self Cite

“…Organic dielectrics have the potential to yield flexible and biodegradable devices through low‐temperature and solution processing techniques, however they typically suffer from higher leakage currents, a larger number of defects, and lower capacitances. [ 6–9 ] In contrast, inorganic dielectrics have lower leakage currents with well characterized performance metrics, but these materials require higher processing temperatures, higher operating voltages, and are not amenable to printing processes or many flexible applications. [ 10 ] An “ideal” dielectric material for OTFTs would need to possess a high dielectric constant (high‐ k ), low leakage currents, and no hysteresis.…”

Section: Introductionmentioning

confidence: 99%

“…[ 31 ] When compared against the previous PVA/bilayer structures, TPCL has the advantages of being environmentally friendly and orthogonally processable when used as a low‐ k dielectric atop PVA. [ 6,32,33 ]…”

Section: Introductionmentioning

confidence: 99%

High Performance Organic Electronic Devices Based on a Green Hybrid Dielectric

Tousignant

Rice

Niskanen

et al. 2021

As the cost of electronics decreases, the demand for short‐term and single‐use applications, such as smart packaging, increases. Consequently, there is significant need for electronically active biodegradable materials to reduce the environmental impact of disposable electronic devices. A bilayer dielectric is developed based on environmentally friendly, low‐cost solution‐processable polymers, fabricated by thermally crosslinking a toluene diisocyanate‐terminated polycaprolactone (TPCL) layer with the hydroxyl groups of a poly(vinyl alcohol)/cellulose nanocrystal (CNC) blended dielectric (PVAC). Metal–insulator–metal (MIM) capacitors are fabricated and characterized under ambient and humid conditions. The incorporation of a TPCL layer in the bilayer dielectric results in a large reduction in moisture sensitivity when compared to neat PVAC without significantly altering the dielectric constant. When utilized as a dielectric in organic thin‐film transistors (OTFTs), the transistors prepared with the PVAC/TPCL dielectric have greater on/off ratios and hole mobilities, with reduced hysteresis compared to devices fabricated with PVAC. Furthermore, the fabricated OTFTs function at operating voltages six times lower when compared against a traditional silicon dioxide (SiO2) dielectric. The facile processing, combined with superior device performance, makes this green bilayer dielectric a promising candidate material for biodegradable disposable electronic applications.

“…Therefore, several polymers have been shown to obtain good chemical resistance through the use of specific additional treatments. [121,122] For example, Teng et al [123] designed a double-layer polymer dielectric structure to overcome the above-mentioned issue for high efficient carrier transport. The double-layer dielectric employs high-k polyvinyl alcohol (PVA) and low-k cross-linked poly(4-vinylphenol) (PVP) stack structure.…”

Section: Polymer Dielectric Materialsmentioning

confidence: 99%

Recent Advances in Flexible Organic Synaptic Transistors

Liu

Huang

et al. 2021

organic electronic devices have attracted substantial attention. [18][19][20][21][22][23][24] However, many issues still exist. For instance, the flexible substrates can be easily bent and thus cause damage to the devices or affect their electrical performance. Moreover, the flexible substrates are sensitive to operating conditions and are unstable during longterm operation. [25][26][27][28][29] Therefore, many research groups have dedicated their efforts to study and improve the flexibility and stretchability of organic electronic devices. [30][31][32][33] In recent years, organic three-terminal synaptic transistors have evolved from two-terminal devices to avoid the problem of crosstalk between adjacent cells. [34] This is an evolutionary structural design to improve the function of organic synaptic devices. In addition, the organic three-terminal synaptic transistors can be designed to form a highly interconnected neural network system. [35] At the same time, the organic three-terminal synaptic transistors can concurrently receive and read stimuli, which is conducive to the design of multiple input devices. [36] Currently, the threeterminal artificial synapses devices based on flexible organic transistors are considered to be the representative structures of biomimetic devices, which can be used to simulate the plasticity of biological synapses. [37,38] Compared with the traditional inorganic synaptic devices, the flexible organic synaptic transistors (FOSTs) can be used to simulate the plasticity of the human brain with a simpler structure and lower manufacturing cost. Therefore, a FOST is a promising component of future organic neuromorphic systems. [39][40][41][42][43][44][45][46] To date, the FOSTs have been widely used in wearable electronic devices and intelligent e-skins. [47][48][49] In 2018, a flexible artificial afferent nerve was reported by Xu et al. [47] representing significant progress toward the development of intelligent e-skin and soft robotics. This paper reviews the recent progress in the development of FOSTs and their applications in neuromorphic systems. Generally, the FOSTs are divided into four categories: flexible organic floating-gate synaptic transistors (FO-FGSTs), flexible organic ferroelectric-gate synaptic transistors (FO-FeGSTs), flexible organic electrolyte-gate synaptic transistors (FO-EGSTs), and flexible organic optoelectronic synaptic transistors (FO-OSTs). First, a brief introduction of the device structure mostly used in the FOSTs is provided. Then, the selection of substrate materials, gate dielectric materials, organic channel materials, and electrode materials in the FOSTs is summarized. Next, the major advances of these FOSTs and their potential applications are reviewed and discussed. Lastly, the summary, outlook, and In recent years, flexible organic synaptic transistors have attracted considerable attention due to their flexibility, biocompatibility, easy processability, and reduced complexity. Flexible organic synaptic transistors have functions and structures sim...