KR102620492B1 - Transistor comprising self-assembled monolayers for sensing nitrogen dioxide gas and manufacturing method thereof - Google Patents

Abstract

The present invention fabricated a sensitive NO ₂ sensor based on an organic transistor by introducing various self-assembled monolayers (SAMs) as gas interaction modifiers. The SiO ₂ surface was modified using four different SAMs, and the effect of surface properties on the performance of the transistor-based sensor was investigated with various NO ₂ concentrations. Molecular dynamics simulations revealed that SAMs with N-containing functional groups interacted strongly with the target NO ₂ molecules, and this trend showed good agreement with the NO ₂ sensitivity results.

Description

Transistor for sensing nitrogen dioxide gas including self-assembled monomolecular film and method of manufacturing same

The present invention relates to a transistor for sensing NO ₂ gas including a self-assembled monomolecular film and a method of manufacturing the same.

Real-time monitoring of harmful gases requires functional materials that are highly portable, easy to process, robust, and have high sensitivity and quick response.

Conjugated polymers are considered promising sensing materials because they are flexible, highly water-soluble, and lightweight. In particular, gas sensors based on organic field-effect transistors (OFETs) have attracted attention due to their high resolution through signal amplification.

Sensor-based transistor signals usually arise from interactions between gas molecules and charge carriers. Gas molecules must pass through the active layer from the top to the buried channel to interact with the gas analytes and the changing carriers of the channel area.

Conjugated polymer films are generally composed of amorphous shapes and nano-sized crystalline particles, so a large free volume and abundant grain boundaries are unavoidable in the active layer. These free volumes and grain boundaries provide a path for gas molecules to diffuse into the active layer.

On the other hand, inorganic gate dielectrics such as SiO ₂ have a high density and the interatomic distance is shorter than the size of gas molecules, so it is difficult for gas molecules to penetrate into the dense inorganic dielectric. Gas molecules diffusing into the semiconductor thin film can interact with polymer molecules and change the current significantly even when the gas is present in parts-per-million concentrations.

In OFET-based gas sensors, the adsorption properties of gas molecules into or on the surface of the bulk binding polymer can be improved by controlling the interaction with gas molecules by adjusting the functional group and polarity of the binding polymer. Gas molecules adsorbed on the coupled polymer generate a dipole moment that has a significant impact on the charge carrier density of the OFET. The main charge transfer in OFETs occurs near the interface between the semiconductor and the gate dielectric.

Therefore, controlling these interface characteristics is also an efficient way to improve the current and sensing characteristics of OFETs. The adsorption of gas molecules is mainly controlled by the surface properties of the gate dielectric in the channel region. However, the effect of gas adsorption on sensor performance has not been extensively studied.

Korean Patent Publication No. 10-2017-0009820

In order to solve the above problems, the present invention manufactured a sensitive OFET-based NO ₂ sensor by introducing self-assembled monolayers (SAMs) with various functional groups as gas interaction regulators.

The SiO ₂ surface of the gate dielectric was modified using a set of four SAMs, and the effect of surface properties on the performance of the OFET-based sensor was investigated at various NO ₂ concentrations.

Nitrogen dioxide (NO ₂ ) is one of the most dangerous gaseous pollutants because it causes acid rain, induces the formation of fine dust, and can cause cancer due to its high reactivity.

The conjugated polymer poly(3-hexylthiophene) (P3HT) was used as a charge transfer host in the semiconductor layer of OFET, and the sensing performance according to the crystallinity of the P3HT thin film was investigated.

SAM with N-containing functional groups strongly interacts with NO ₂ gas molecules, resulting in high sensitivity to NO ₂ . To investigate the relationship between the sensing performance of the P3HT thin film and the SAM type, the present invention calculated the interaction energy between NO ₂ gas molecules and the functional groups of various SAM molecules based on the minimum bond structure.

Conjugated polymers have strong potential as sensing materials because they are flexible, easy to manufacture, and lightweight. Organic gas sensors based on field-effect transistors have attracted attention due to their high resolution through signal amplification. The main charge transfer in organic transistors occurs near the interface between the semiconductor and the gate dielectric. Therefore, controlling these interface characteristics also provides an efficient approach to improve the current level and sensing properties of these devices. The present invention fabricated a sensitive NO ₂ sensor based on an organic transistor by introducing various self-assembled monolayers (SAMs) as gas interaction modifiers. The SiO ₂ surface was modified using four different SAMs, and the effect of surface properties on the performance of the transistor-based sensor was investigated with various NO ₂ concentrations. Molecular dynamics simulations revealed that SAMs with N-containing functional groups interacted strongly with the target NO ₂ molecules, and this trend showed good agreement with the NO ₂ sensitivity results.

According to one embodiment of the present invention, a substrate; a gate electrode located on the substrate; A dielectric layer located over the entire surface of the substrate including the gate electrode; An organic semiconductor layer located on the front surface of the dielectric layer and containing poly(3-hexylthiophene) (P3HT); and source and drain electrodes spaced apart from each other on the organic semiconductor layer, and between the dielectric layer and the organic semiconductor layer is a self-assembled monolayer (Self-) having a nitrogen (N)-containing functional group by modifying the dielectric layer. Provides a transistor for nitrogen dioxide gas detection in which Assembled Monolayers (SAMs) are placed.

Self-assembled monolayers (SAMs) with nitrogen (N)-containing functional groups include N-[3-(trimethoxysilyl)propyl]ethylenediamine (en-APTAS) self-assembled monolayers (SAMs). SAMs).

The nitrogen (N)-containing functional group of the N-[3-(trimethoxysilyl)propyl]ethylenediamine (en-APTAS) self-assembled monolayers (SAMs) is electron-donating NH ₂ It is characterized by being a functional group.

Another embodiment of the present invention includes the steps of a) forming a gate electrode on a substrate; b) forming a dielectric layer covering the gate electrode on the substrate; c) modifying the surface of the dielectric layer using a coupling agent; d) forming an organic semiconductor layer by spin coating a solution containing poly(3-hexylthiophene) (P3HT) on the dielectric layer; and e) forming the source and drain electrodes, wherein in the step of modifying the surface of the dielectric layer using the coupling agent, self-assembled monolayers having a nitrogen (N)-containing functional group are formed on the dielectric layer. , SAMs) are formed, and a method for manufacturing a transistor for detecting nitrogen dioxide gas is provided.

The self-assembled monolayers (SAMs) with the nitrogen (N)-containing functional group are N-[3-(trimethoxysilyl)propyl]ethylenediamine (en-APTAS) self-assembled monolayers (SAMs). SAMs).

The nitrogen (N)-containing functional group of the N-[3-(trimethoxysilyl)propyl]ethylenediamine (en-APTAS) self-assembled monolayers (SAMs) is electron-donating NH ₂ It is characterized by being a functional group.

In the present invention, various SAMs were introduced as gas-interactive modifiers in the channel region and their potential as analysis channel materials was examined. We found that nitrogen-containing functional groups (N1, N2) enable SAMs to function as gas absorption sites in the channel region, resulting in high reactivity toward NO ₂ molecules and ultrafast reaction rates.

The organic sensor modified with en-APTAS(N2) showed the best detection performance with a two-fold improvement in detection performance compared to the P3HT sensor made with a bare OH substrate.

Additionally, to investigate the relationship between reaction sensing performance and SAM type, the interaction reaction energy between NO ₂ gas molecules and the functional groups of various SAM molecules in the minimum binding structure was calculated. MD simulation results confirmed that NO ₂ molecules were tightly adsorbed on the N ₂ surface, and this trend appeared to be in good agreement with the QM results.

Figure 1 is a photograph showing the contact angles of (a) deionized water and (b) diiodomethane droplets on five different substrates, (c) contact angles in deionized water and (d) diiodomethane, and (e) calculated surface energy. It is a graph of values.
Figure 2 is an AFM phase image of five different substrates of P3HT thin films fabricated using (a) chloroform and (b) dichlorobenzene (the inset shows the AFM height image of the P3HT thin film).
Figure 3 shows ultraviolet-Vis absorption spectra for five substrates of P3HT thin films fabricated using (a) chloroform and (b) dichlorobenzene. The A _0-0 /A _0-2 peak ratio and thin film thickness for five substrates of P3HT thin films produced using (c) chloroform and (d) dichlorobenzene are shown.
Figure 4 shows the GIXD pattern plotted with (a) linear and (b) logarithmic axes of the P3HT thin film fabricated using chloroform and the GIXD pattern plotted with (c) linear and (d) logarithmic axes of the P3HT thin film fabricated using dichlorobenzene. It is a graph that represents a pattern.
Figure 5 is a function plot of I _D versus V _G at a fixed drain voltage (V _D = -60 V) for five different substrates of P3HT thin films fabricated using (a) chloroform and (b) dichlorobenzene, chloroform, and dichlorobenzene. (c) This is a graph of the average magnetic field effect mobility for five different substrates of P3HT thin films produced using benzene.
Figure 6 shows repetitive gas sensing curves of P3HT thin films fabricated using (a) chloroform and (d) dichlorobenzene, (b) chloroform and (e) characterized when the films were exposed to continuous pulses of NO ₂ (10 ppm). ) A graph showing the enlarged first gas sensing cycle of the P3HT thin film fabricated using dichlorobenzene, and the sensing parameters of the gas sensor of the P3HT thin film fabricated using (c) chloroform and (f) dichlorobenzene.
Figure 7 shows the drain current (I _D ) change of gas sensors manufactured using (a) chloroform and (c) dichlorobenzene when exposed to NO ₂ at various concentrations from 50 to 10 ppm and (b) chloroform (d). Graph showing a linear fit showing the relative responsiveness as a function of NO ₂ concentration for sensors fabricated using dichlorobenzene (the inset shows sensitivity calculated from the slope of the linear fit graph).
Figure 8 is a schematic diagram showing NO ₂ adsorption on a P3HT thin film spin-coated on (a) a bare OH substrate and (b) an N ₂ substrate.
Figure 9 is a diagram showing the optimized shape of the NO ₂ binding structure.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only intended to aid understanding of the present invention, and the scope of the present invention is not limited to these examples in any way.

1. Experimental example

1.1 Fabrication of self-assembled monolayer and gas sensor

The OFET-based gas sensor was fabricated as a top-contact bottom-gate type on a highly doped Si wafer. Heat-grown SiO ₂ with a thickness of 300 nm was used as the dielectric layer. To remove organic contaminants, the SiO ₂ /Si wafer was washed in piranha solution (70 vol% H ₂ SO ₄ and 30 vol% H ₂ O ₂ ) for 30 minutes at 70°C and then rinsed with deionized water.

In the present invention, four binders: N-[3-(trimethoxysilyl)propyl]ethylenediamine (en-APTAS, N2), 4-aminobutyltriethoxysilane (ABTS, N1), trichloro(octyl) Silane (OTS, C) and trichloro(1H,1H,2H,2H-perfluorooctyl)silane (FOTS, F) were used. All coupling agents were applied using the dipping method.

The reaction flask was loaded with 200 mL of anhydrous toluene and a SiO ₂ /Si substrate washed with piranha solution. Coupling agent solution (0.3 mL) was added to achieve self-assembly on the Si wafer, and the treatment was performed for 1 hour. The SAM-treated wafer was then rinsed with toluene and ethanol and heated in an oven at 130°C for 1 hour. Heated SAM treated wafers were sonicated in toluene and ethanol and then cleaned by vacuum drying before characterization.

The positional regularity and molecular weight of the p-type semiconducting polymer P3HT (Rieke metal) were 95% and 58 kDa, respectively. P3HT solution (chloroform (CF) 2 mg·mL ^-1 , dichlorobenzene (DCB) 4 mg·mL ^-1 ) (Sigma-Aldrich) was stirred at 50°C for 1 hour and then stirred at room temperature for 6 hours. As a result, the P3HT solution was spin-coated on SiO ₂ /Si substrates modified with various SAMs (CF 2500 rpm, 60 s, DCB 1500 rpm, 60 s). For UV-Vis spectrophotometric analysis, P3HT thin films were coated on clean transparent substrates using the same process as previously described.

1.2 Characteristics

The surface energy of the modified substrate was calculated from the contact angle of deionized water and diiodomethane (CH ₂ I ₂ ) droplets on the Si wafer surface. According to the Owens-Wendt method equation,

이고, 여기서 θ는 접촉각, 는 물의 자유 에너지, 및 은 각각 고체와 젖은 액체의 표면 에너지를 나타낸다. 위첨자 D와 P는 각각 분산 성분과 극성 성분을 나타낸다.

, where θ is the contact angle, is the free energy of water, and represents the surface energy of solid and wet liquid, respectively. The superscripts D and P represent the dispersive component and the polar component, respectively.

The surface morphology of P3HT thin films was observed by optical microscopy (OM, Olympus BX51) and atomic force microscopy (AFM) (Multimode 8, Bruker).

UV-Vis absorption spectra were recorded using a UV-Vis spectrophotometer (Perkin Elmer, Lambda 365).

The grazing-incidence X-ray diffraction (GIXD) pattern of the P3HT thin film was imaged using a high-resolution X-ray diffractometer (Rigaku, Smart Lab).

The charge transfer characteristics of the P3HT thin film were characterized using a semiconductor analyzer (Keithley 4200-SCS) at room temperature and vacuum.

The sensor response of the OFET to NO ₂ (10-50 ppm) was measured using a gas sensor (Precision Sensor Systems, GASENTEST) with a gate voltage (VG) of -30 V and a drain voltage (VD) of -30 V at room temperature.

1.3 Computing details

All quantum mechanical (QM) calculations were performed using the M06-2X functional and the 6-31G** basis set. To find the initial NO ₂ bond structure, all possible bond structures were considered and compared based on their relative energy values. The NO ₂ binding structure was fully optimized and verified as a minimal structure without imaginary frequencies. Quantum mechanics (QM) calculations were performed using Jaguar implemented in the Schrödinger Material Science Suite 2021-1.

Additionally, molecular dynamics (MD) simulations were performed to verify the binding affinity trend. Crystal SiO ₂ structure (CIF database code: 1010954) was used to build the SiO ₂ layer. SiO ₂ unit cell dimensions were 42.72 Å Х 42.72 Å Х 185.33 Å including 20 Å substrate thickness and 165 Å vacuum slab.

The SiO ₂ slab structure was relaxed via Brownian minimization and a 5.0 ns NVT (isostatic-isothermal) ensemble using a Nose-Hoover thermostat at 300 K. The functional end groups replaced the hydrogen atoms on the SiO ₂ (001) surface to completely cover the surface. Additionally, the structure was relaxed using the same procedure used for the SiO ₂ slab structure. Finally, NO ₂ molecules were placed on the surface and relaxed through a 2.0 ns NVT ensemble.

A 5.0 ns NVT MD simulation was further performed to describe the binding energy between NO ₂ and the surface. All MD simulations were performed using Desmond implemented in Schrödinger Material Science Suite 2021-1.

2. Results and discussion

The surface of SiO ₂ , the gate insulation layer, was surface-modified using four different self-assembled single molecules, and a hydroxide substrate treated with only surface cleaning was prepared and analyzed to compare surface modification characteristics.

Figure 1 shows the contact angles measured for five substrates. First, we observed surface modification-induced changes in the water contact angle of the substrate. For the hydroxyl substrate, the water contact angle was very small (4.95°). However, it gradually increased from N ₂ to F, reaching a maximum value of 110° in the fluorine-terminated SAM. These results confirm that hydrophobicity increased as the ends of the self-assembled alkyl chains varied from nitrogen to carbon to fluorine.

The contact angle was measured again using a nonpolar solvent, CH ₂ I ₂ , and the surface energy was calculated using the Owens-Wendt method equation. The results are summarized in Figures 1c-1e for water contact angle and CH ₂ I ₂ contact angle results. It was confirmed that the surface energy decreased more for the substrate surface modified with F or C than for the substrate surface modified with OH or N.

As shown in Figure 2, the P3HT thin film showed no morphological change when functional groups were introduced into the modified SiO ₂ substrate. The roughness and morphology of P3HT thin films on bare OH and SAM-treated SiO ₂ substrates were similar. However, the solvent played an important role in determining the surface morphology of P3HT thin films. The thin film prepared from the DCB solution showed a much rougher surface (3.1-3.7 nm) than the thin film prepared from the CF solution, and also showed highly crystalline and granular surface morphology.

UV-Vis absorption spectra were acquired to analyze changes in the molecular order of P3HT thin films spin-coated using CF and DCB on five substrates with various surface properties. The UV-Vis spectrum of the P3HT thin film (Figure 3) shows the A _0-2 peak at λ = 520 nm, which is due to the intrachain π-π* transition.

The A _0-1 and A _0-0 peaks corresponding to the first and second transitions of interchain π-π interactions appear at ~558 and ~605 nm, respectively.

The UV-Vis absorption intensity was proportional to the film thickness determined according to the Beer-Lambert law. The thickness of these thin films was 18 to 21 nm regardless of the characteristics of the substrate. When a thin film is produced using a solution of the same concentration, if the solvent has a high boiling point, the solidification process is slow, so the film becomes thinner. Therefore, in the present invention, the concentration was adjusted to make the thickness similar.

The A _0-0 peak intensity of the P3HT thin film spin-coated from the DCB solution was higher than that of the P3HT thin film fabricated from the CF solution. These larger intrachain interactions in P3HT thin films processed in DCB solution are due to the slow evaporation rate caused by using high-boiling main solvents. However, surface properties did not affect the absorption peak of the thin film.

Out-of-plane GIXD analysis of P3HT thin films prepared from CF and DCB solutions was used to investigate the molecular orientations associated with five different surface properties (Figure 4).

The pattern shows the X-ray diffraction peaks of P3HT molecules in an out-of-plane orientation. The peaks correspond to the (100) intermolecular main chain stacking layer thickness of 16.9–17.5 Å and the π-π interconnection layer (010) thickness of ∼3.8 Å. As shown in Figures 4c and 4d, the intensity of the (100) diffraction peak of the P3HT thin film prepared from the DCB solution was much stronger than that of the thin film prepared from the CF solution. Additionally, the scattering profile showed a better defined diffraction pattern, indicating that the P3HT thin film prepared on DCB had a higher degree of molecular orientation. However, the functional groups of SAM did not affect the UV-Vis absorption spectrum and diffraction pattern of P3HT thin film, which was consistent with AFM analysis.

The performance of the P3HT thin film in the NO ₂ sensor was investigated by fabricating OFET. Figures 5a and 5b show the transmission characteristics of OFETs based on P3HT thin films fabricated from CF and DCB solutions. The average field effect mobility values of OFET are shown in Figure 5c.

The device performance was strongly influenced by the functional groups of SAMs on the SiO ₂ substrate. In other words, device performance improved as hydrophobicity increased. The drain current value at VG = 0 V is improved by two orders of magnitude for OFETs treated with fluorine-containing SAMs compared to OFETs treated with nitrogen-containing SAMs, which is due to the carrier oxidation by various SAM functional groups. This indicates that the density (carrier density) is strongly modulated. Drain current was also affected by solvent boiling point, and DCB devices showed improved electrical performance compared to CF devices regardless of SiO ₂ surface treatment conditions. These results are consistent with the results of several previously reported studies. The charge transport behavior of P3HT thin films can vary depending on surface properties and solvent boiling point.

The NO ₂ gas sensing properties of each organic thin film transistor device modified with various functional groups were evaluated under 10 ppm NO ₂ at room temperature (FIG. 6). The P3HT gas sensor showed a change in current after injecting NO ₂ gas for 20 seconds, and showed recovery after injecting N ₂ gas for 200 seconds. Charge carriers in the P3HT sensor accumulated in the channel region upon exposure to NO ₂ , a gas with strong electron-withdrawing properties.

The P3HT gas sensor modified with functional groups containing nitrogen (N1, N2) showed higher reactivity and higher response rate with a greater increase in current level (I _D (t)/I _D (0)) (Figures 6a-6c). . In particular, the P3HT sensor modified with en-APTAS(N2) showed the best detection performance, twice that of the P3HT sensor manufactured using a bare OH substrate. This result is due to the strong interaction between NO ₂ gas molecules and the electron-donating NH ₂ end group of en-APTAS.

Figures 6d and 6f show the low response of the gas sensor with P3HT thin film fabricated using highly crystalline DCB solution. This result indicates that NO ₂ gas molecules penetrated more easily into the amorphous P3HT thin film due to the large free volume between polymer chains. The sensing performance was improved due to the N-containing functional groups and low crystallinity of the thin film.

In the present invention, we further monitored the dynamic response of the P3HT sensor modified with N ₂ or OH as a function of NO ₂ concentration of 10-50 ppm (Figure 7).

Additionally, the sensor modified with N ₂ showed a greater dynamic response in response to fluctuations in NO ₂ concentration. Importantly, in the case of P3HT thin films fabricated from CF solution, the N ₂ -modified sensor showed at least four times higher sensitivity than the bare OH-modified sensor, as calculated from the reactivity slope as a function of NO ₂ concentration. These results suggest that nitrogen-containing functional groups can greatly improve NO ₂ gas sensing ability due to the strong interaction between NO ₂ gas molecules and amine groups (Figure 8).

In contrast to the excellent NO ₂ response of the P3HT gas sensor, the P3HT film showed no distinguishable sensing response to NH ₃ gas molecules, regardless of the crystallinity and surface properties of the film.

To explain the relationship between the response performance of the P3HT sensor and the SAM type, the interaction energies between NO ₂ gas molecules and various functional groups of the SAM coupling agent molecules were calculated based on the minimum binding structure (Figure 9).

The binding energies obtained from QM calculations are summarized in Table 1.

Among the functional groups investigated, the N ₂ functional group of en-APTAS exhibits the largest binding energy (-7.18 kcal·mol ^-1 ), meaning that NO ₂ gas binds most tightly to the N ₂ functional group, while the F functional group of FOTS has a binding energy of 5. Among other functional groups, it shows a loose binding affinity (-2.24 kcal·mol ^-1 ). The binding energy between the SAMs-modified SiO ₂ surface and NO ₂ gas molecules was also calculated for the most stable binding configuration (Figure 9).

According to MD simulation results, NO ₂ molecules were able to adsorb on surfaces modified with OTS (C functional group) or FOTS (F functional group). NO ₂ molecules are adsorbed only on bare OH and surface-modified SiO ₂ with en-APTAS(N2) or ABTS(N1) surfaces.

The interaction energies obtained from MD simulations are summarized in Table 2, where E _Total corresponds to the interaction energy between NO ₂ and the surface, and E _Coulomb and E _vdW correspond to the Coulomb and Van der Wals energy terms, respectively. A small E _Total value means close bonding between NO ₂ molecules and the surface. Therefore, the MD simulation results confirmed that NO ₂ molecules were tightly adsorbed on the N ₂ surface, and this trend appeared to be in good agreement with the QM results.

3. Conclusion

In the present invention, various SAMs were introduced as gas-interactive modifiers in the channel region and their potential as analysis channel materials was examined. We found that nitrogen-containing functional groups (N1, N2) enable SAMs to function as gas absorption sites in the channel region, resulting in high reactivity toward NO ₂ molecules and ultrafast reaction rates. The organic sensor modified with en-APTAS(N2) showed the best detection performance with a two-fold improvement in detection performance compared to the P3HT sensor made with a bare OH substrate. Additionally, to investigate the relationship between reaction sensing performance and SAM type, the interaction reaction energy between NO ₂ gas molecules and the functional groups of various SAM molecules in the minimum binding structure was calculated. MD simulation results confirmed that NO ₂ molecules were tightly adsorbed on the N ₂ surface, and this trend appeared to be in good agreement with the QM results. The approach presented here provides guidelines for obtaining gas sensors with both high sensitivity and high selectivity using surface modification.

The present invention described above is not limited to the above-described embodiments, as various substitutions and changes can be made by those skilled in the art without departing from the technical spirit of the present invention. .

Claims (6)

Board;
a gate electrode located on the substrate;
A dielectric layer located over the entire surface of the substrate including the gate electrode;
An organic semiconductor layer located on the front surface of the dielectric layer and containing poly(3-hexylthiophene) (P3HT); and
It includes source and drain electrodes spaced apart from each other on the organic semiconductor layer,
Between the dielectric layer and the organic semiconductor layer, self-assembled monolayers (SAMs) with nitrogen (N)-containing functional groups are disposed by modification of the dielectric layer,
The organic semiconductor layer includes amorphous poly(3-hexylthiophene) (P3HT),
Self-assembled monolayers (SAMs) with nitrogen (N)-containing functional groups include N-[3-(trimethoxysilyl)propyl]ethylenediamine (en-APTAS) self-assembled monolayers (SAMs). Transistors for nitrogen dioxide gas detection (SAMs).
delete According to paragraph 1,
The nitrogen (N)-containing functional group of the N-[3-(trimethoxysilyl)propyl]ethylenediamine (en-APTAS) self-assembled monolayers (SAMs) is electron-donating NH ₂ A transistor for detecting nitrogen dioxide gas, characterized in that it is a functional group.
a) forming a gate electrode on the substrate;
b) forming a dielectric layer covering the gate electrode on the substrate;
c) modifying the surface of the dielectric layer using a coupling agent;
d) forming an organic semiconductor layer by spin coating a solution containing poly(3-hexylthiophene) (P3HT) on the dielectric layer; and
e) forming source and drain electrodes,
In the step of modifying the surface of the dielectric layer using the coupling agent, self-assembled monolayers (SAMs) with nitrogen (N)-containing functional groups are formed on the dielectric layer,
The organic semiconductor layer includes amorphous poly(3-hexylthiophene) (P3HT),
Self-assembled monolayers (SAMs) with nitrogen (N)-containing functional groups include N-[3-(trimethoxysilyl)propyl]ethylenediamine (en-APTAS) self-assembled monolayers (SAMs). Method for manufacturing a transistor for detecting nitrogen dioxide gas (SAMs).
delete According to clause 4,
The nitrogen (N)-containing functional group of the N-[3-(trimethoxysilyl)propyl]ethylenediamine (en-APTAS) self-assembled monolayers (SAMs) is electron-donating NH ₂ A method of manufacturing a transistor for detecting nitrogen dioxide gas, characterized in that it is a functional group.