Vertical Organic Thin Film Transistor Research Articles

High-k dielectric based high performance vertical organic thin film transistor for flexible low power applications

The basic performance parameters such as threshold voltage, drain current and saturation mobility play an important role for any transistor-based devices. The planar organic TFT provides a good performance but it is still not satisfactory. Therefore, in this paper, a vertical channel TFT (D5) is proposed that exhibits a significant improvement for threshold voltage V t , drain current I Dmax and saturation mobility μ sat in comparison to planar devices. The proposed vertical device (D5) is 44 and 24 times enhanced in comparison with planar device D1 in terms of I Dmax and μ sat , correspondingly. Furthermore, this paper compares five different vertical-channel device architectures (D2, D3, D4, D5, D6 & D7). Out of these structures, our proposed novel structure (D5) shows remarkable performance in terms of drain current (528 μA) and saturation mobility (80.8 cm2/V.s). As compared to the best mentioned vertical devices D2, D3 and D7, the proposed device exhibits 41.8 %, 15.6 % and 27.8 %, increment in drain current, respectively. Additionally, the proposed device exhibits about 2.7, 5.2 and 3.5 times improvement in comparison with D2, D3 and D7 correspondingly. The reasons for this better performance of the proposed device have been explained by vertical and horizontal cutline analysis.

Preparation and analysis of single and hybrid metal-phthalocyanine organic phototransistors and comparison of their photoelectric properties

Vertical organic thin film transistors (VOTFT) in a five-layer structure of ITO/MPc/Al/MPc/Cu were prepared using a single phthalocyanine or two hybrid phthalocyanine material co-blended films as the active layer. The prepared single phthalocyanine device and the mixed phthalocyanine material device experimented with static operating characteristics. The threshold voltage of the device of ZnPc is 1 V, while the threshold voltage of the hybrid material is reduced, and the threshold voltage of the device of CuPc mixed with ZnPc can reach 0.4 V. The results of the photoelectric characteristics of the devices show that the light sensitivity of the hybrid material is significantly better than that of the single material. The light sensitivity of the 1:1 blend of PbPc mixed with ZnPc device has the greatest photosensitivity, 5.37 times that of ZnPc and 141.62 times that of PbPc. The device switching parameters for the hybrid materials are ton = 0.4 ms and toff = 0.44 ms, which switching characteristic times in the sub-millisecond range. The cut-off frequency of the hybrid materials has also increased, with the highest mobility VOTFT of ZnPc mixed with PbPc reaching a cut-off frequency of 4.6 kHz.

전기화학적으로 산화된 투과성 베이스 전극을 갖는 수직구조 유기 트랜지스터

Vertical organic thin film transistors (VOTFTs) are emerging electronic devices that can overcome the limitations of conventional organic thin film transistors (OTFTs) based on lateral architecture. Here, organic permeable base transistors (OPBTs) are formed with an oxide layer on the base electrode through an electrochemical process called anodization, and this oxide layer acts as a dielectric layer. Through this electrochemical method, the manufacturing process is simplified and the charge carrier transport of the VOTFT is improved. In this study, the thickness of AlOx formed by anodizing the Al electrode was calculated through the capacitance-voltage measurement of the metal-insulator-metal device, and OPBT operations were observed according to the anodizing potential and interfacial layer, respectively. In addition, we observed the specific behaviors of vertical OPBT depending on the applied potential correlations between middle base electrode and bottom collector electrode.

Preparation and Characterization of the Organic Thin Film Transistors by Adopting the ZnPc0.5-PbPc0.5 Co-Deposited Material as the Active Layer

The organic film co-deposited by Zinc Phthalocyanine (ZnPc) and Lead Phthalocyanine (PbPc) was used as the active layer of the vertical organic film diode, and we obtained the co-deposition ratio of the devices with the better performance of 1:1. We made the vertical organic thin film transistor (VOTFT) with the same process again, compared the co-deposited VOTFT with the VOTFT with a single organic material (ZnPc, PbPc) as the active layer and tested the static operating characteristics of the device. The results show that the carrier mobility of ZnPc-PbPc-VOTFT is more than three times higher than that of ZnPc-VOTF and PbPc-VOTFT. When [Formula: see text][Formula: see text]V and [Formula: see text][Formula: see text]V, the output current [Formula: see text] of ZnPc-PbPc-VOTFT is up to 0.2[Formula: see text]mA, which is 12 times that of ZnPc-VOTFT and 27 times that of PbPc-VOTFT. Overall, the electrical performance of ZnPc-PbPc-VOTFT is better than ZnPc-VOTFT and PbPc-VOTFT.

Preparation and operating characteristics analysis for high-speed PbPc organic thin film transistors with cut-off frequency of 77 kHz

In this work, we fabricated vertical organic thin film transistors (VOTFTs) with lead phthalocyanine (PbPc) as the active layer and analyzed the operating characteristics and current transfer mechanism of VOTFTs. The results show that the quiescent output current of VOTFTs is not saturated, and the output current can be modulated by requiring different gate voltages. The switching parameters of the VOTFTs are ton = 2.5 μs, toff = 3.5μs, and the switching characteristic time reaches the microsecond level. When a sine wave dynamic signal is applied to the gate electrode, the cut-off frequency fc = 77 kHz. The experimental results demonstrate that short channel and vertical structure of VOTFTs make up for organic semiconductor material defects of low carrier mobility and realize high speed and low driving voltage of organic devices. Electric field intensity of depletion layer in the gate region is 7×107V/m, and high electric field intensity makes carriers tunneling become the major transport mode. The tunnel injection model is used to analyze the carrier transport inside the transistor. The results show that the operating current of the transistor conforms to the tunneling effect theory.

High-Performance Quantum-Dot Light-Emitting Transistors Based on Vertical Organic Thin-Film Transistors.

In this work, a novel vertical quantum-dot light-emitting transistor (VQLET) based on a vertical organic thin-film transistor is successfully fabricated. Benefiting from the new vertical architecture, the VQLET is able to afford an extremely high current density, which allows most of the organic thin film transistors (OTFT) even with low mobility (for instance, poly(3-hexylthiophene)) to drive a quantum-dot light-emitting diode (QLED), which was previously unavailable. Moreover, the hole injection barrier could be modulated by the additional gate electrode, which precisely optimizes the charge balance in the device, a critical issue in QLED, resulting in the precise control of current density and brightness of the VQLET. The VQLET shows a high performance with a maximum current efficiency of 37 cd/A. Furthermore, integrating OTFT and QLED into a single device, the VQLET features drastic advantages by realizing active matrix quantum-dot light-emitting diodes (AMQLEDs), which significantly reduces the number of transistors and frees the large area fraction occupied by transistors. Hence, these results indicate that the VQLET provides a new strategy for realizing a low-cost, solution-processed, high-performance OTFT-AMQLED for the flat panel display technology. Moreover, the novel design offers a unique method to exquisitely control the charge balance and maximize the efficiency the QLED.

High‐Performance Vertical Organic Transistors

Vertical organic thin-film transistors (VOTFTs) are promising devices to overcome the transconductance and cut-off frequency restrictions of horizontal organic thin-film transistors. The basic physical mechanisms of VOTFT operation, however, are not well understood and VOTFTs often require complex patterning techniques using self-assembly processes which impedes a future large-area production. In this contribution, high-performance vertical organic transistors comprising pentacene for p-type operation and C60 for n-type operation are presented. The static current-voltage behavior as well as the fundamental scaling laws of such transistors are studied, disclosing a remarkable transistor operation with a behavior limited by injection of charge carriers. The transistors are manufactured by photolithography, in contrast to other VOTFT concepts using self-assembled source electrodes. Fluorinated photoresist and solvent compounds allow for photolithographical patterning directly and strongly onto the organic materials, simplifying the fabrication protocol and making VOTFTs a prospective candidate for future high-performance applications of organic transistors.

Sub Ten Micron Channel Devices Achieved by Vertical Organic Thin Film Transistor

Sub Ten Micron Channel Devices Achieved by Vertical Organic Thin Film Transistor

Sub Ten Micron Channel Devices Achieved by Vertical Organic Thin Film Transistor

Sub Ten Micron Channel Devices Achieved by Vertical Organic Thin Film Transistor