Advanced Electronic Materials最新文献

Organic Thin Film Transistors

In article number 2300362, Yun Ho Kim and co-workers present a uniform water-borne polyimide thin film as a gate dielectric layer in large-scale flexible organic thin film transistors (OTFTs) over 100 cm². A bar-coating technique is used to adjust coating solution surface tension with an alcohol as a co-solvent. This approach yields low standard deviation and nearly 100% device yield in fabricating 500 OTFT devices.

InGaAs Synaptic Phototransistors

In article number 2300437, Jae-Hoon Han, Won Jun Choi, Ki Jun Yu and co-workers develop a flexible In_0.53Ga_0.47As synaptic phototransistor which exhibits superior performance to biological synapses with rapid operation under 1 ms and remarkably low energy consumption at the atto to femto joule level. These findings open up exciting possibilities for implementing intricate synaptic functions using high-speed, low-power short-wave infrared synaptic phototransistors.

The performances of simplified single-layer phosphorescent organic light-emitting diodes (SL-PhOLEDs) have significantly increased and they now appear to be a promising alternative to multi-layer PhOLEDs. The blue and white emissions, far more challenging than all the other colours, are still particularly desired. Herein, a high efficiency host material for blue emitting SL-PhOLED using the blue emitter FIr6 is reported, which is particularly interesting as it displays an emission at shorter wavelengths than the well-known FIrpic emitter, almost exclusively reported in the SL-PhOLEDs literature. The host material investigated herein is constructed on the electron-rich quinolinoacridine and displays when incorporated in FIr6-based SL-PhOLEDs, an external quantum efficiency (EQE)⟩10% and a low Von of 3.1 V. This is the first work passing an EQE of 10% with FIr6 as an emitter. This host also reaches a very high EQE of 19% when used with the green emitter Ir(ppy)2acac, this performance being among the highest recorded for green SL-PhOLEDs. Finally, as white SL-PhOLEDs involve blue emitting SL-PhOLEDs, this host is also used with a combination of blue and yellow emitters. An extremely high EQE of 24% is reached with CIE coordinates of (0.40;0.48). These findings show the real potential of the quinolinoacridine fragment to reach high performance multi-colour SL-PhOLEDs.

Large, open-gate transistors made from metal nanoparticle arrays offer possibilities to build new electronic devices, such as sensors. A nanoparticle necklace network (N³) of Au particles from 300 K to cryogenic temperatures exhibit a nonohmic I–V_d behavior, I ≈ (V_d–V_T)^ζ, where V_T is a conduction gap and ζ is a constant critical exponent. The conduction gap in N³, made from disordered networks of 1D chains of 10 nm diameter Au particles exhibits room temperature (RT) gating. Although the I–V_d behavior at RT is identical to Coulomb blockade, the conduction is modulated by field-assisted tunneling exhibiting classical critical behavior. In this study, based on three results, invariance of V_T on gating, invariance of V_T on temperature, and zero–bias conductance, a sharp transition temperature at ≈140 K is discovered where the conduction mechanism switches from Coulomb blockade to classical critical percolation behavior. The N³ architecture allows the reconciliation of the Coulomb blockade versus activation process as a sharp thermal transition to serve as a model system to study the exotic behavior in nanogranular-metallic materials. The novel global critical behavior to local Coulomb blockade governed transition in these N³ architectures may potentially lead to novel sensors and biosensors.

Two-dimensional layered transition metal dichalcogenides (TMDCs) are promising memristive materials for neuromorphic computing systems. Despite extensive experimental work, the underlying switching mechanisms are still not understood, impeding progress in material and device functionality. This study reveals the dominant role of defect dynamics in the switching process of 2D TMDC materials. The switching process is governed by the formation and annihilation dynamics of a local vacancy depletion zone. It explains the distinct features of the device characteristics observed experimentally, including fundamentally different device behavior previously thought to originate from multiple mechanisms. Key influence factors are identified and discussed with a fully coupled and dynamic charge transport model for electrons, holes, and ionic point defects, including image-charge-induced Schottky barrier lowering (SBL). Thermal effects and local Joule heating are considered by coupling the transient heat transfer equation to the electronic properties. The model is validated with hysteresis and pulse measurements for various lateral 2D MoS₂-based devices, strongly corroborating the relevance of vacancy dynamics in TMDC devices and offering a new perspective on the switching mechanisms. The insights gained from this study can be used to extend the functional behavior of 2D TMDC memristive devices in future neuromorphic computing applications.