Performance Of Organic Field-effect Transistors Research Articles

Influence of Polymer Gate Dielectric on Organic Field‐Effect Transistors: Interdependence of Molecular Weight, Solvent Polarity, and Surface Energy—A Case Study with PMMA and Pentacene

AbstractThe semiconductor/dielectric interface controls the performance of organic field‐effect transistors (OFETs). Herein, the influence of both the molecular weight and the polarity of the solvent of a poly(methyl methacrylate) (PMMA)‐based gate dielectric on the performance of pentacene OFETs is systematically investigated, by studying surface energy, surface roughness, morphology, leakage current, and capacitance of the dielectric. Various existing views on the role of the surface energy are considered while deriving a correlation. Larger pentacene grains are observed when the film is grown on high molecular weight‐PMMA films cast from high dipole moment‐solvent. The electrical properties of the corresponding OFETs show great improvement compared to those of OFETs fabricated with low molecular weight‐PMMA film as the gate dielectric, irrespective of the solvent. The authors attribute this enhanced performance to the increased surface energy of the polymeric dielectric which turns out to be a strong function of its molecular weight and the dipole moment of the solvent. Bias‐stress measurements on the OFETs confirm this correlation.

Toward Efficient Charge Transport of Polymer-Based Organic Field-Effect Transistors: Molecular Design, Processing, and Functional Utilization

ConspectusPolymer-based organic field-effect transistors (OFETs) have attracted great attention owing to their significantly improved performance and the recently emerged prospects for broad applications. The charge carrier mobility of polymer-based OFETs has been improved from 10–5 to more than 10 cm2 V–1 s–1 over the past three decades. With the carrier mobility close to or higher than that of amorphous silicon, the application fields of polymer-based OFETs have been extended from sensing to logic or drive circuits. During OFET operation, the charge carriers are successively injected in and then transferred across the semiconducting channel under an external electric field. The behavior of the charge carriers is determined by both charge injection and charge transport. Well-matched frontier molecular orbital (FMO) energy levels and optimized hierarchical structures of semiconducting polymers are essential for the realization of high-performance polymer-based OFETs.In this Account, we mainly demonstrate our recent progress in molecular design strategies and fabrication processing methods for high-performance semiconducting polymers. Moreover, we provide some examples of integrated applications of polymer-based OFETs. The convenient FMO energy level modulation and excellent molecular designability of donor–acceptor (D–A) conjugated polymers facilitate studies on their performance enhancement in OFETs. Proper molecular design of the D–A polymer backbone and side chain can significantly contribute to charge injection enhancement, transport pathway establishment, and trap reduction, thereby resulting in efficient charge transport. Moreover, special fabrication processes of OFET devices can further enhance the charge transport by optimizing the hierarchical structures of semiconducting polymers, thereby enhancing their carrier mobility and stability. By employing high-performance semiconducting polymers as the semiconducting channel of OFETs, various applications can be implemented. These applications range from small-scale logic signal processing and periodic signal generation to complex visual perception systems, indicating broad application prospects in human life. The works on performance improvement and functional utilization of the semiconducting polymers in OFETs might provide insights for molecular design strategies and applications for future plastic electronics.

Interface engineering of gate dielectrics with multifunctional self-assembled monolayers in copper phthalocyanine based organic field-effect transistors

To enhance the performance of organic field-effect transistors (OFETs) not only properties of gate oxide, active organic layer and source and drain needs to be improved but it is essential to engineer the different interfaces in OFETs. In this aspect, the gate oxide/organic semiconductor and electrode/organic semiconductor interfaces are engineered by various functional groups to obtain high performance OFETs. CuPc-based FETs were fabricated by surface treatment with various self-assembled monolayers (SAMs); octadecyltrichlorosilane(OTS), hexamethyldisilazane (HMDS) and pentaflurothiophenol (PFBT), at an interface between gate oxide or gate dielectric layer and active organic layer. The influence of SAMs on the device performance was examined in the present study. Low-voltage operating CuPc-based OFETs with high field effect mobility were fabricated in current work. Significant development in the device parameters, especially the field effect mobility was observed for HMDS treated CuPc-FET as compared to the OTS and PFBT treated CuPc-FET. The OFETs with the SAM-treatments exhibit the field effect mobility was 5.6 × 10-2cm2 V−1 s−1 (OTS) to 1.369 cm2 V−1 s−1 (PFBT-treated) and 1.537 cm2 V-1s−1 (HMDS-treated).The improved performance of the OFET were related to the improve crystallinity with larger grain size of the organic semiconductor with reduced trap densities and improved contact resistance between the metal electrode and organic semiconductor due to the introduction of monolayer at the interface.

50.3: Invited Paper: High performance organic field effect transistors: from fabrication parameters to novel applications

50.3: <i>Invited Paper:</i> High performance organic field effect transistors: from fabrication parameters to novel applications

Impact of interfacial trap states on achieving bias stability in polymer field-effect transistors

Low operational stability and undesirable shift of electrical properties at ambient conditions are the major barriers in the commercialization of organic field-effect transistors (OFETs). In this study, we report an improvement in operational stability of solution-processable polymer Poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno[3,2-b]thiophene)] (DPPDTT) based OFETs by applying bias stress for short times. Two types of devices were fabricated using i) bare Si3N4 as gate dielectric that offers higher interfacial traps and ii) using an additional layer of PMMA along with Si3N4 that offers lower interfacial traps. The OFET with PMMA layer shows better performance i.e. threshold voltage around 15 V, mobility~0.2 cm2/V.s and current on/off ratio in the range of 106. The bias stress measurements show the initial decrease in the performance parameters in both devices. However, the device with lower traps shows a smaller decrease in the performance parameters and achieves a stable performance when devices are put under continuous gate bias stress, while the high trap state device continued to degrade. The reported results provide a route to achieve good stability in the electrical performance of OFETs in ambient conditions.

Three-dimensional CuPc films decorated with well-ordered PVA parallel nanofiber arrays for low concentration detecting NO2 sensor

Abstract Well-ordered polyvinyl alcohol (PVA) parallel nanofiber arrays (PNAs) were fabricated by using electrospinning receiving board with clined gap. A three-dimensional (3D) copper phthalocyanine (CuPc) organic field effect transistor (OFET) sensor was obtained by evaporating CuPc on the PVA PNAs. This 3D structure is conducive to the multi angle adsorption and desorption of the target gas and active layers. The detection limit of the obtained sensors is lower, and the response and recovery time are also shorter. Compared with single CuPc films and CuPc films with disordered PVA nanofibers sensors, the minimum detection concentration is reduced by one third. The CuPc/PVA PNAs sensors have been successfully used in real-time monitoring of NO2 at 0.3 ppm. The response and recovery time of the CuPc/PVA PNAs sensors are both 0.02 min for 25 ppm NO2. The response and recovery time are 350 and 130 times faster than those of CuPc sensors with disordered PVA nanofibers, respectively. Humidity has little effect on the response of the sensor. This convenient and effective method to prepare high performance OFET sensors can be extended to other gas monitoring.

Development of semiconducting polymers based on a novel heteropolycyclic aromatic framework

The choice of appropriate building blocks and the development of new donor and acceptor units are essential for the creation of high-performance donor-acceptor (D-A)-type semiconducting polymers. In addition, the introduction of π-extended aromatic frameworks into polymer main chains is a useful strategy to facilitate dense π-π stacking structures with long-range order in the solid-state, thereby enabling efficient carrier transport in organic electronics. However, such highly π-extended aromatic frameworks have rarely been reported due to the need for multiple steps. This focus review describes the synthesis and characterization of D-A polymers based on three π-extended heteropolycyclic aromatic frameworks, using phenanthro[1,2-b:8,7-b’]dithiophene (PDT) as a weak donor and alkoxy-substituted anthra[1,2‑c:5,6‑c’]bis([1,2,5]thiadiazole) (ATz) and vinylene-bridged 5,6-difluorobenzo[c][1,2,5]thiadiazole (FBTzE) as new thiadiazole-based acceptor units. In addition, their applications to organic electronic devices, such as organic field-effect transistors (OFETs) and organic photovoltaic cells (OPVs), and the detailed relationship between the thin-film structure and device performance in OFETs and OPVs were investigated. These results indicate that these novel π-extended heteropolycyclic aromatic frameworks may serve as building units for the development of wide-bandgap p-type semiconducting polymers for nonfullerene solar cells and low-bandgap n-type semiconducting polymers for OFETs and OPVs. Our recent studies on the development of semiconducting polymers based on three novel π-extended heteropolycyclic aromatic frameworks, using phenanthro[1,2-b:8,7-b’]dithiophene (PDT) as a weak donor and alkoxy-substituted anthra[1,2‑c:5,6‑c’]bis([1,2,5]thiadiazole) (ATz) and vinylene-bridged 5,6-difluorobenzo[c][1,2,5]thiadiazole (FBTzE) as new thiadiazole-based acceptor units are described. Furthermore, their detailed relationships between the thin-film structure and device performance in organic field-effect transistors (OFETs) and organic photovoltaic cells (OPVs) were investigated. These results demonstrated that these novel π-extended heteropolycyclic aromatic frameworks have great potential as building units for high-performance OFETs and OPVs.

Effect of contact resistance in organic field‐effect transistors

AbstractContact resistance (RC) is universally present in organic field‐effect transistors (OFETs) and the performance of OFETs can be easily affected by RC, which will result in poor performances such as low mobility (μ), large threshold voltage (VT), and non‐ideal transfer/output characteristics. In this article, we provide a comprehensive review on the effects of RC in OFETs. We start with a brief introduction of the origin of RC and its effects on OFETs, followed by the commonly used methods for extraction of RC. Then, methods for reducing RC are thoroughly discussed. Especially, fabricating monolayer molecular crystal (MMC) OFETs is highlighted as one of the key solutions to reduce RC effectively. The final section describes the challenges in MMCs preparation and concludes with an outlook for further reducing RC to enhance the performances of OFETs.

Azulene-Based π-Functional Materials: Design, Synthesis, and Applications.

ConspectusAzulene, an isomer of naphthalene, is a molecule of historical interest for its unusual photophysical properties, including a beautiful blue color derived from the narrow HOMO-LUMO energy gap and anti-Kasha fluorescence from S2 to S0. More recently, it has attracted increasing attention for its novel electronic structure, including an electron-rich five-membered ring and an electron-deficient seven-membered ring with a dipole moment of 1.08 D resulting from resonance delocalization, its different reactivities at odd and even positions, and its stimuli-responsive behavior. As a key building block, azulene has been used in various fields because of its unique physicochemical properties. Recent studies have demonstrated the great potential of azulene for constructing advanced organic materials. However, exploring azulene-based materials has long been hindered by challenges in molecular design and synthesis. Most of the reported azulene-based materials have the azulene unit incorporated through the five-membered ring or seven-membered ring. Creating azulene-based novel building blocks for optoelectronics and using 2,6-connected azulene units to construct conjugated polymers that can adequately utilize the "donor-acceptor" structure of azulene remained underexplored before our contributions. Besides, for most azulene-fused polycyclic aromatic hydrocarbons (PAHs) and heteroaromatics, the azulene substructures were created during later synthesis stages, and the use of azulene derivatives as starting materials to design and synthesize PAHs and heteroaromatics intelligently is still limited.In this Account, we summarize our efforts on the design, synthesis, and applications of azulene-based π-functional materials. Our studies start with the creation of novel π-conjugated structures based on azulene. The design strategy, synthesis, and optoelectronic performance of the first class of azulene-based aromatic diimides, 2,2'-biazulene-1,1',3,3'-tetracarboxylic diimide (BAzDI) and its π-extended and π-bridged derivatives, are presented. Notably, antiparallel stacking between adjacent azulene units derived from azulene's dipole was observed in single crystals of BAzDI and its derivatives. Besides, we developed an azulene-fused isoindigo analogue, azulenoisoindigo, which combines the merits of both isoindigo and azulene, including reversible redox behavior and reversible proton responsiveness. Then we discuss our contributions to the design and synthesis of 2,6-azulene-based conjugated polymers. By incorporation of 2,6-connected azulene units into the polymeric backbone, two conjugated polymers with high organic field-effect transistor (OFET) performance were developed. Two 2,6-azulene-based polymers with proton responsiveness and high electrical conductivity upon protonation were also provided. We also discuss our recent studies on azulene-based heteroaromatics. Two azulene-fused BN-heteroaromatics were designed and synthesized, and they exhibited a selective response to fluoride ion and unexpected deboronization upon the addition of trifluoroacetic acid. An unexpected synthesis of azulene-pyridine-fused heteroaromatics (Az-Py) by reductive cyclization of 1-nitroazulenes and the OFET performance of Az-Py-1 are included. Afterward, we discuss several examples of azulene-capped organic conjugated molecules. The molecules capped with the five-membered ring of azulene favor hole transport, whereas the ones capped with the seven-membered ring favor electron transport.

Recent advances on π-conjugated polymers as active elements in high performance organic field-effect transistors

As high-performance organic semiconductors, π-conjugated polymers have attracted much attention due to their charming advantages including low-cost, solution processability, mechanical flexibility, and tunable optoelectronic properties. During the past several decades, the great advances have been made in polymers-based OFETs with p-type, n-type or even ambipolar characterics. Through chemical modification and alignment optimization, lots of conjugated polymers exhibited superior mobilities, and some mobilities are even larger than 10 cm2·V−1·s−1 in OFETs, which makes them very promising for the applications in organic electronic devices. This review describes the recent progress of the high performance polymers used in OFETs from the aspects of molecular design and assembly strategy. Furthermore, the current challenges and outlook in the design and development of conjugated polymers are also mentioned.

Improving Ideality of P‐Type Organic Field‐Effect Transistors via Preventing Undesired Minority Carrier Injection

AbstractElectron injection plays a crucial role in arousing the double‐slope characteristics for p‐type organic field‐effect transistors (OFETs) with narrow‐bandgap organic semiconductors (OSCs). This issue will not only result in the misrepresentation of OFET performance but also may cause device instability, hence impeding their further development in real‐world applications. A facile and highly efficient approach is developed to circumvent this issue by implementing modification on the electrode/organic semiconductor interface. An ultrathin layer of wide‐bandgap OSC with suitable energy levels is introduced to block the undesirable electron injection. By this means, typical double‐slope behaviors and bias stress stability in the p‐type OFETs can be significantly improved. Using 2,8‐difluoro‐5,11‐bis(triethylsilylethynyl) anthradithiophene‐based OFETs the double‐slope behaviors of as‐fabricated devices are effectively converted to near‐ideal behaviors after modification, leading to a dramatic improvement of average reliability from 65.11% to 91.76%. Furthermore, the positive drift of transfer curves under prolonged bias stress is also successfully suppressed. This strategy demonstrates good universality and can provide a new guideline for the fabrication of OFETs with ideal behaviors.

The effects of cesium lead bromide quantum dots on the performance of copper phthalocyanine-based organic field-effect transistors

Highly luminescent all-inorganic cesium lead bromide (CsPbBr3) perovskite quantum dots (QDs) have been extensively used as a photosensitizer in optoelectronic devices, while p-type small-organic-molecule copper phthalocyanine (CuPc) is also widely used as a photoactive material in solar cells, organic field-effect transistors (OFETs), etc. In this paper, we report the preparation of a CsPbBr3-QDs/CuPc heterostructure to study the effect of CsPbBr3-QDs on CuPc. The optical properties of both CuPc and the QDs/CuPc heterostructure were compared and contrasted using UV–vis absorbance and photoluminescence (PL) measurements. Furthermore, to study their electronic and charge transfer features, we fabricated field-effect transistors (FETs) on both pristine CuPc and QDs/CuPc heterostructure thin films and studied their photoresponsive electrical characteristics. Both pristine and QDs/CuPc-based FETs showed an enhancement in current and carrier mobility under illumination. The enhancement in the current and carrier mobility of the QDs/CuPc-based FETs is due to a large number of photoexcited charge carriers. We also observed that the current and carrier mobility in the QDs/CuPc heterostructure-based FET were lower than those of the pristine CuPc-based FET. This can be explained by the n-type doping effect of CsPbBr3 QDs on CuPc, which reduces the accumulation of holes in the active p-channel near the insulating layer and causes charge to be transferred from the QDs to the CuPc. Thus, we have observed a charge transfer effect in the CsPbBr3 QDs/CuPc heterostructure, which can be used in optoelectronic devices.

Improving the Robustness of Organic Semiconductors through Hydrogen Bonding.

Molecular organization plays an essential role in organic semiconductors since it determines the extent of intermolecular interactions that govern the charge transport present in all electronic applications. The benefits of hydrogen bond-directed self-assembly on charge transport properties are demonstrated by comparing two analogous pyrrole-based, fused heptacyclic molecules. The rationally designed synthesis of these materials allows for inducing or preventing hydrogen bonding. Strategically located hydrogen bond donor and acceptor sites control the solid-state arrangement, favoring the supramolecular expansion of the π-conjugated surface and the subsequent π-stacking as proved by X-ray diffraction and computational calculations. The consistency observed for the performance of organic field-effect transistors and the morphology of the organic thin films corroborate that higher stability and thermal robustness are achieved in the hydrogen-bonded material.

Benzo/Naphthodifuranone-Based Polymers: Effect of Perpendicular-Extended Main Chain π-Conjugation on Organic Field-Effect Transistor Performances.

For polymer semiconductors, the backbone structure plays an essential role in determining their physicochemical properties and charge transport behaviors. In this work, two donor-acceptor-type polymers (P-BDF and P-NDF) based on benzodifuranone (BDF) and naphthodifunarone (NDF) as electron-deficient moieties and indaceno-dithiophene as electron-rich groups are designed, synthesized and, for the first time, applied in organic field-effect transistor. P-BDF and P-NDF differ from their backbone structures while P-BDF has a more planar backbone conformation due to its smaller conjugated core size and P-NDF features a perpendicular-extended main chain structure. As a result, P-BDF polymer exhibits bathochromic optical absorption, deeper molecular orbital energy levels, and more importantly, closer π-stacking and stronger aggregation in the solid state and thus affords a more promising hole mobility of up to 0.85 cm2 V-1 s-1 in OFET devices, while that of the P-NDF-based devices is only 0.55 cm2 V-1 s-1 . The results suggest the great potential of BDF/NDF-type chromophores in constructing novel organic semiconductors and also indicate that the main chain coplanarity of polymer semiconductors is more essential than the sole extension of π-conjugations (especially at the perpendicular direction of polymer main chains) for the design of high-performance OFET materials.

Improving the charge transport performance of solution-processed organic field-effect transistors using green solvent additives

Green solvent additives were employed as non-solvents in binary solvent systems to enable the pre-aggregation of organic semiconductors and enhance the electrical performance of organic field-effect transistors and complementary-like inverters.

Morphological and structural comparison of TIPS-PEN:PS and neat TIPS-PEN films grown onto cPVP-patterned plastic substrates

In the present study, spray-coated blends of 6,13-Bis(triisopropylsilylethynyl)pentacene (TIPS-PEN) with Polystyrene (PS) insulating polymer were employed to improve the performance of spray-coated neat TIPS-PEN Organic Field-Effect Transistors (OFETs) on plastic substrates. By combining TIPS-PEN with PS insulating polymer, control over the TIPS-PEN crystallization behavior can be achieved. A surface morphology study on the TIPS-PEN blended with PS films at an optimized weight ratio of 0.8:0.2 was carried out, in order to investigate the phase separation phenomena between the two components within the blend. The crystallinity and the crystalline characteristics of the sprayed TIPS-PEN:PS blend films were also investigated and compared to those of the sprayed neat TIPS-PEN films. Finally, these improved characteristics of the blend-based films are correlated with the extracted electrical parameters (mobility value, on/off current ratio, threshold voltage value) of the sprayed TIPS-PEN:PS blend OFETs and are compared with those of the sprayed neat TIPS-PEN OFETs, both in terms of values and inter-device uniformity.

Role of new synthesized diethylenetriamine-based protic ionic liquids in organic semiconductor devices

The charge carrier transport and related transport layers are extremely essential issue for obtaining high-efficient Organic Light Emitting Devices (OLEDs) and high-performance Organic Field Effect Transistor (OFETs). In an attempt to light on the effects of diethylenetriamine (DETA) based protic ionic liquids (PILs) on OLEDs and OFET, PILs were used as a hole transport layer and dielectric layer in OLEDs and OFETs, respectively. Charge transfer properties of synthesized two novel DETA based PILs (PIL1 and PIL2) on OLED device performance were investigated by spinning on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) due to their ionic characteristics. The PIL2 based OLED device showed threefold luminance (1038 cd/m2) compared to reference device (360 cd/m2) without effecting its light output emission wavelength. When analyzed OFET performances, device with PIL1 possessed the highest performance in terms of low threshold voltage (VTh∼1.5 V), operating voltage (V∼5 V) and reproducibility in the ambient atmosphere in comparison to device without PILs. Moreover, Density Functional Theory (DFT) calculations and impedance spectroscopic analysis of ionic liquids (ILs) were investigated. The carrier transport properties and mobility measurement has been identified with impedance spectroscopy of the devices. PIL1 had p-type transport property with mobility up to 0.198 cm2/Vs while the device without PILs had mobility 0.0237 cm2/Vs.

A Solution Processable Dithioalkyl Dithienothiophene (DSDTT) Based Small Molecule and Its Blends for High Performance Organic Field Effect Transistors.

The 3,5-dithiooctyl dithienothiophene based small molecular semiconductor DDTT-DSDTT (1), end functionalized with fused dithienothiophene (DTT) units, was synthesized and characterized for organic field effect transistors (OFET). The thermal, optical, electrochemical, and computed electronic structural properties of 1 were investigated and contrasted. The single crystal structure of 1 reveals the presence of intramolecular locks between S(alkyl)···S(thiophene), with a very short S-S distance of 3.10 Å, and a planar core. When measured in an OFET device compound 1 exhibits a hole mobility of 3.19 cm2 V-1 s-1, when the semiconductor layer is processed by a solution-shearing deposition method and using environmentally acceptable anisole as the solvent. This is the highest value reported to date for an all-thiophene based molecular semiconductor. In addition, solution-processed small molecule/insulating polymer (1/PαMS) blend films and devices were investigated. Morphological analysis reveals a nanoscopic vertical phase separation with the PαMS layer preferentially contacting the dielectric and 1 located on top of the stack. The OFET based on the blend comprising 50% weight of 1 exhibits a hole mobility of 2.44 cm2 V-1 s-1 and a very smaller threshold voltage shift under gate bias stress.

Thienoisoindigo (TII)-Based Quinoidal Small Molecules for High-Performance n-Type Organic Field Effect Transistors.

A novel quinoidal thienoisoindigo (TII)‐containing small molecule family with dicyanomethylene end‐capping units and various alkyl chains is synthesized as n‐type organic small molecules for solution‐processable organic field effect transistors (OFETs). The molecular structure of the 2‐hexyldecyl substituted derivative, TIIQ‐b16, is determined via single‐crystal X‐ray diffraction and shows that the TIIQ core is planar and exhibits molecular layers stacked in a “face‐to‐face” arrangement with short core intermolecular distances of 3.28 Å. The very planar core structure, shortest intermolecular N···H distance (2.52 Å), existence of an intramolecular non‐bonded contact between sulfur and oxygen atom (S···O) of 2.80 Å, and a very low‐lying LUMO energy level of −4.16 eV suggest that TIIQ molecules should be electron transporting semiconductors. The physical, thermal, and electrochemical properties as well as OFET performance and thin film morphologies of these new TIIQs are systematically studied. Thus, air‐processed TIIQ‐b16 OFETs exhibit an electron mobility up to 2.54 cm2 V−1 s−1 with a current ON/OFF ratio of 105–106, which is the first demonstration of TII‐based small molecules exhibiting unipolar electron transport characteristics and enhanced ambient stability. These results indicate that construction of quinoidal molecule from TII moiety is a successful approach to enhance n‐type charge transport characteristics.

Electrode and dielectric layer interface device engineering study using furan flanked diketopyrrolopyrrole\u2013dithienothiophene polymer based organic transistors

We successfully demonstrated a detailed and systematic enhancement of organic field effect transistors (OFETs) performance using dithienothiophene (DTT) and furan-flanked diketopyrrolopyrrole based donor–acceptor conjugated polymer semiconductor namely PDPPF-DTT as an active semiconductor. The self-assembled monolayers (SAMs) treatments at interface junctions of the semiconductor–dielectric and at the semiconductor–metal electrodes has been implemented using bottom gate bottom contact device geometry. Due to SAM treatment at the interface using tailored approach, the significant reduction of threshold voltage (Vth) from − 15.42 to + 5.74 V has been observed. In addition to tuning effect of Vth, simultaneously charge carrier mobility (µFET) has been also enhanced the from 9.94 × 10−4 cm2/Vs to 0.18 cm2/Vs. In order to calculate the trap density in each OFET device, the hysteresis in transfer characteristics has been studied in detail for bare and SAM treated devices. Higher trap density in Penta-fluoro-benzene-thiol (PFBT) treated OFET devices enhances the gate field, which in turn controls the charge carrier density in the channel, and hence gives lower Vth = + 5.74 V. Also, PFBT treatment enhances the trapped interface electrons, which helps to enhance the mobility in this OFET architecture. The overall effect has led to possibility of reduction in the Vth with simultaneous enhancements of µFET in OFETs, following systematic device engineering methodology.