Flexible organic ion-gated transistors with low operating voltage and light-sensing application

ABSTRACT: Ion-gated transistors are attracting significant attention due to their low operating voltage (<1 V) and modulation of charge carrier density by ion-gating media. Here we report flexible organic ion-gated transistors based on the high mobility donor–acceptor conjugated copolymer poly[4-(4,4-dihexadecyl 4H-cyclopenta[1,2-b:5,4-b']-dithiophen-2-yl)-alt[1,2,5]thiadiazolo[3,4c]pyridine](PCDTPT) and the ionic liquid [1-ethyl-3 methylimidazolium bis(trifluoromethylsulfonyl)imide] as the ion-gating medium. Electrical characteristics of devices made on both [rigid (SiO2/Si) and flexible (polyimide (PI))] substrates showed very similar values of hole mobility (∼1 cm2 V−1 s−1) and ON–OFF ratio (∼105). Flexible ion-gated transistors showed good mechanical stability at different bending curvature radii and under repetitive bending cycles. The mobility of flexible ion-gated transistors remained almost unchanged upon bending. After 1000 bending cycles the mobility decreased by 20% of its initial value. Flexible photodetectors based on PCDTPT ion-gated transistors showed photosensitivity and photoresponsivity values of 0.4 and 93 AW−1

Highly sensitive capacitive cell based on a novel CuTsPc-TiO2 nanocomposite electrolytic solution for low-temperature sensing applications

This work demonstrates a highly efficient electrochemical cell based on the hybrid nanofluid of titanium dioxide (TiO2) nanoparticles dispersed in a water-based copper (II) phthalocyanine-tetrasulfonic acid tetrasodium salt (CuTsPc) solution. A chemical cell of ITO/nanofluid/ITO has been fabricated to study the effect of temperature variations towards its capacitance and resistance. The resultant device possessed capacitive sensing mechanism, and the synergistic hybridization of the two different sensing elements lead to the superior performance as compared to the single CuTsPc based device. The hybrid device outperformed the pristine CuTsPc based device in terms of sensitivity, stability, linearity, response/recovery and possessed narrow hysteresis loop

UV- ozone treated graphene oxide/ PEDOT:PSS bilayer as a novel hole transport layer in highly efficient and stable organic solar cells

The utilization of UV-ozone (UVO) treated graphene oxide (GO)/PEDOT:PSS bilayer as hole transport layer (HTL) in solution processed organic solar cells (OSCs) is demonstrated. The HTLs were treated with UVO for 0, 5, 10 and 15 min. The 10 min treated OSC showed the best performance and displayed power conversion efficiency (PCE) of 5.24%, much higher than the untreated OSC device. This enhanced performance is mainly driven by improvements in the short circuit current (∼10.82 mA/cm2) as well as the fill factor (∼57%) that is ascribed to the moderate reduction of GO and increased work function (WF) of PEDOT:PSS after UVO treatment, which improved the contact conditions between the HTL and photoactive layer. Consequently, extraction efficiency of the photogenerated holes is increased, while recombination probability of holes and electrons in the photoactive layer is decreased. Moreover, the UVO-reduction of GO and consequently increased conductivity of reduced-GO (r-GO) has been modeled and proved using the density functional theory (DFT) simulation. Meanwhile, the 15 min UVO-treated OSC device showed severe reduction in the PCE that dropped to 2.11%, possibly due to couple of factors such as decomposition of chemical bonds, significant increase in the series resistance and pronounced drop in the photovoltaic performance parameters

Enhanced sensitivity of zinc phthalocyanine-based microporous humidity sensors by varying size of electrode gaps

The use of organic materials has become an increasingly important issue in sensing devices in recent times. Phthalocyanine is among the most promising materials in this undertaking. Zinc phthalocyanine (ZnPc) based microporous device was fabricated and its capacitance was utilized as the sensing mechanism for a humidity sensor. The effect of the electrode gap of the device on the electrical properties was investigated along with the correlation between the device’s performances and the morphology of the sensing film. Using the solution-processed spin coating method, the capacitive type humidity sensor devices have been fabricated in a planar geometry of Al/ZnPc/Al with the presence of a microporous template. The size of electrode gaps measured with a surface profiler was 53.00 ± 0.06 μm, 119.00 ± 0.03 μm and 286.00 ± 0.01 μm. The surface morphology was characterized by using transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS). Analysis of the experimental results showed that the device with the shortest electrode gap (53.00 μm) produced the best sensitivity of 1.03 ± 0.04 pF/%RH than that of the longer gaps. Additionally, hysteresis as well as response and recovery performances have also been investigated

Involvement of opioid receptors in Boesenbergia pandurata's esssential oil (BPEO)-induced antinociceptive activity in animal model of nociception

Boesenbergia pandurata is a folklore remedy for relieving stomach, abdominal, joint, and muscular pain. Previous study from our research group has shown that Boesenbergia pandurata’s essential oil (BPEO) possesses antinociceptive activity against chemical and thermal models of pain. The present study was conducted to evaluate participation of opioid receptors in BPEO-induced antinociceptive activity. The involvement opioid receptors were assessed using acetic acid-induced abdominal writhing test. The acetic acid-induced writhing test was conducted by administering the non-selective opioid receptor antagonists (naloxone) 15 minutes before administration of BPEO orally, and selective opioid receptor antagonists (beta-funaltrexamine, norbinaltorphimine, and naltrindole) 1 day before BPEO administration. 0.6% acetic acid was later injected intraperitoneally and 5 minutes after the injection mice was observed for writhing response in 30 minutes time span. It was demonstrated that oral administration of BPEO 300 mg/kg produced 82.19% inhibition of nociception induced by 0.6% acetic acid injection. Opioid receptor antagonists administration solely did not modify acetic acid-induced nociceptive behavior. However, administration of naloxone (non-selective opioid antagonist) significantly increases the nociceptive response of animal receiving BPEO in the acetic acid-induced writhing test. Furthermore, administration of beta-funaltrexamine (mu opioid receptor antagonist and norbinaltorphimine kappa opioid receptor antagonist) significantly reserved antinociceptive activity induced by BPEO. Together, these result suggested participation of opioid receptors in inducing antinociceptive in animal model. In conclusion, BPEO may exert its antinociceptive activity through activation of mu opioid receptor, as well as kappa opioid receptor

Adoption of internet banking among bank customers in Kota Bharu / Nur Adilah Roslan

According to Bank Negara Malaysia (BNM) websites, Internet banking provides a fast and convenient way of performing common banking transactions, such transferring funds from savings account to current account, or even to a third party's account. Through Internet banking, payments to relevant parties also can be made, such as utility bills and assessment tax. Under the Bank Negara Malaysia guidelines, all licensed banking institutions in Malaysia are allowed to establish the informational Web sites. Only banking institutions under the banking and Financial Institutions Act 1989 and the Islamic Banking Act 1983 are allowed to offer Internet banking services in Malaysia (Bank info, 2005). The main primary of this study is to determine the adoption of internet banking among bank customers in Kota Bharu. In this research, the researcher had used convenience sampling from non-probability sampling to distribute 180 questionnaires among bank customers in Kota Bharu. The data were analyzed by using SPSS through the descriptive analysis, regression analysis and reliability analysis .An analysis of the data also were made by using The Structural Equation Modeling (SEM) using AMOS: This statistical technique is employed to model the inter-relationship among the variables in the study (adoption of internet banking, perceived usefulness, ease of use trust, compatibility and costs saved) simultaneously. This study indirectly helped to promote internet banking service to the residents in Kota Bharu and also to get the reason why customers not using this services. This research also will help financial institutions especially the bank to improve internet banking services thus to fit with the customer’s needs and wants. From the analysis, the researcher found that perceived usefulness, ease of use and compatibility has a significant relationship with the adoption of internet banking. However, trust and costs saved has a significant negative relationship between adoption of internet bankin

Vanadyl tetrabutyltetrakis(Dimethylamino) phthalocyanine based thin films for organic sensor and transistor applications / Nur Adilah Roslan

Organic electronic devices have been successively making progress into the commercial market to substitute conventional inorganic electronic devices. The endeavor to improve the performance displayed by organic semiconductor materials has urged a substantial number of researchers set to seek new materials. Metal phthalocyanines (MPcs), in particular, have garnered much attention due to their enticing benefits viz., cost efficiency, eco-friendly organic material, as well as thermal and chemical stability. Primarily, this study investigated the physical, morphological, optical, and electrical properties of vanadyl 3,10,17,24-tetra-tert-butyl-1,8,15,22-tetrakis(dimethylamino)-29H,31H-phthalocyanine or synonymously known as vanadyl tetrabutyltetrakis (dimethylamino) phthalocyanine (VTP). Subsequently, this study looked into the potential applications of VTP-based organic semiconductor devices in organic field effect transistor (OFET), as well as optical and humidity sensor. The initial phase of this study is devoted to the characterization of VTP thin films and fabrication of VTP-based OFETs. The photophysical study revealed that the band gap of VTP is 1.39 eV via expression approach, while 1.42 eV via Tauc plot. The highest occupied/lowest unoccupied molecular orbital (HOMO/LUMO) values of VTP were -5.10 eV and -3.90 eV, respectively, as determined via cyclic voltammetry (CV) analysis. The VTP was applied as the active layer in the fabrication of lateral OFETs (LOFETs), which served as a control device, whereby fixed parameters were employed for each layer, similar for the fabrication of vertical OFETs (VOFETs). The LOFETs exhibited poor performance due to the extended channel length between source and drain (S-D) electrodes. In the attempt of addressing this shortcoming, apart from enhancing the performance of LOFETs; the arrangement was altered to resemble that of VOFET, in which capacitor and diode cells were vertically stacked on top of each other. This design minimized the channel length and enhanced the device performance. In attaining optimum thickness for the active layer, VOFET was fabricated with a range of thicknesses; 90 5 nm, 66 5 nm, and 52 5 nm. As a result, VTP thickness at 66 5 nm exerted optimum performance, as it generated maximum current density and the lowest threshold voltage of ~ 37 mA/cm2 and 7.0 0.2 V, respectively. The second phase of this study probed into the fabrication of VTP-based optical organic devices. Initially, the study of optical properties and charge transport via current-voltage (I-V) method was executed. Utilizing the optimized bulk heterojunction (BHJ), ITO/PEDOT:PSS/VTP:PC71BM/Al organic photovoltaics (OPVs) were fabricated by using the solution processed technique. By employing the similar OPV fabrication parameters, the device was used for light sensing application, which falls under the organic optical device category. The light sensor appeared to display high stability, rapid response time, and high sensitivity in the visible light. These features are attributable to the extended ligands in the molecular structure of VTP. The final phase of this study assessed the applicability of VTP as an active layer in the fabrication of organic humidity sensor. Physical characterization that involved structural and wettability evaluations were executed in advance to determine the association between the thickness of sensing film and the performance exerted by the sensor. The Al/VTP/Al humidity sensor devices were fabricated in three thickness values, which revealed that the thinnest sensing film displayed the best performance with a maximum sensitivity of 9.2 pf/%RH. In sum, this study had successfully adopted highly reproducible, solution generating, and cost-efficient fabrication techniques

Investigation of charge transport properties in VTP: PC71BM organic Schottky diode

In this work, the charge transport properties of organic vanadyl 3,10,17,24-tetra-tert-butyl-1,8,15,22-tetrakis(dimethylamino)-29H,31H phthalocyanine (VTP) were investigated. The I-V profile demonstrated by single VTP shows a rectifying behavior, and Schottky diode parameters such as the ideality factor, barrier height, shunt, and series resistance were calculated. Further, the charge transport behavior of single-layer VTP and its blend with phenyl C71 butyric acid methyl ester (PC71BM) was evaluated using the I-V conventional method and diode analysis. In addition, the optimized diode properties of VTP: PC71BM were chosen to evaluate its photovoltaic effect. The current density-voltage (J-V) characteristics were evaluated in both dark and light conditions to determine the key parameters of the photovoltaic effect. The results indicate the optimized VTP: the PC71BM composite blend yielded a relatively low photovoltaic efficiency. However, due to the presence of extended ligands, it gives a very good sensitivity when applied in the organic photodetector device, as reported in our previous work

Investigation of Charge Transport Properties in VTP: PC71BM Organic Schottky Diode

In this work, the charge transport properties of organic vanadyl 3,10,17,24-tetra-tert-butyl-1,8,15,22-tetrakis(dimethylamino)-29H,31H phthalocyanine (VTP) were investigated. The I-V profile demonstrated by single VTP shows a rectifying behavior, and Schottky diode parameters such as the ideality factor, barrier height, shunt, and series resistance were calculated. Further, the charge transport behavior of single-layer VTP and its blend with phenyl C71 butyric acid methyl ester (PC71BM) was evaluated using the I-V conventional method and diode analysis. In addition, the optimized diode properties of VTP: PC71BM were chosen to evaluate its photovoltaic effect. The current density-voltage (J-V) characteristics were evaluated in both dark and light conditions to determine the key parameters of the photovoltaic effect. The results indicate the optimized VTP: the PC71BM composite blend yielded a relatively low photovoltaic efficiency. However, due to the presence of extended ligands, it gives a very good sensitivity when applied in the organic photodetector device, as reported in our previous work

The critical factors that influence the new venture creation by retailers in Kelantan

This study aimed to determine the factors that influence the creation of new businesses by retailers for the retail trade in Kelantan. Framework to explain the creation of new businesses that combines four main perspectives in entrepreneurship that are characteristic of the individual (s) who start a business, an organization that they made, a new business environment, and the process by which new businesses started. Quantitative methods were used to analyse the study and the questionnaire as an instrument, a descriptive analysis and Spearman correlation and multiple correlation test was used to analyse the data. The results showed that the process involved in new ventures is the highest affect to the retailers in Kelantan