effect of crystallization modes in tips-pentacene/insulating polymer blends on the gas sensing properties of organic field-effect transistors - polymer blends
It is well known that mixing organic semiconductors with insulating polymers is an effective way to overcome the disadvantages of a single polymer
Effect transistor (OFETs).
We show that when the solution can be processed organic semiconductor (6,13-bis(
Three C-based milk thistle)And five benzene skills-pentacene)
Mixed with insulating polymer (PS)
, The morphology and structural features of the mixed film may be significantly affected by processing conditions such as rotating coating time.
Although the vertical phase
Separation structure (TIPS-pentacene-top/PS-bottom)
Regardless of the rotational coating time, it is formed on the substrate, and the rotational time controls the growth mode of the tip
Phase-five benzene molecules
Separate the crystals on an insulating polymer.
Excess solvent remaining in samples rotated in a short period of time can lead to convection flow in dry droplets, resulting in 1-dimensional (1D)
Growth model of TIPS-
Five benzene crystals.
In contrast, after proper rotation
Coating time, the best amount of residual solvent in the film results in two-dimensional (2D)
Growth model of TIPS-
Five benzene crystals.
2D spherical crystal of TIPS-
Pentacene is very good for improving oil fields
Effect mobility of fet compared to needle
Like 1D structures, because of the high surface coverage of crystals with unique continuous film structures.
In addition, the porous structure observed in the 2D crystal film allows gas molecules to easily penetrate into the channel region, thus improving the gas sensing performance. Organic field-
Effect transistor (OFETs)
The machined coupled small molecules or polymers are widely studied as components of electronic devices such as flexible displays, sensors, RFID tags and logic circuits.
However, the solution treatment of small molecule semiconductors often poses some problems: their strong π-
π interaction induced non
Their films are uniform form and Dewet from the substrate, resulting in poor electrical performance of the device.
To overcome these problems, small-
Molecular Semiconductors are mixed with insulating polymers with excellent films-
The forming properties and ofet based on this mixture film were prepared using various methods. Blending small-
Molecular Semiconductors with insulating polymers effectively improve their processing performance, promote the environmental stability of ofet based on their design, and provide hybrid films through vertical phases, without losing the inherent charge carrier mobility due to small molecule semiconductorsseparation.
However, in order to improve the electrical performance of devices based on hybrid films, phase-
The separation and crystal of small molecule/insulating polymer mixture should be carefully controlled.
Since the charge carriers in the active layer usually move in the direction parallel to the dielectric surface, the formation of vertical phase separation is ideal.
Recently, many researchers have studied the effects of thermodynamic and kinetic factors affecting the vertical phase separation of organic small molecule/insulating polymer mixtures, I . E. e.
Interaction energy with the substrate surface, Gibbs-
Free energy system, and curing dynamics, small by mixing
Molecular Semiconductors with various insulating polymers.
Vertical phase separation in small molecular semiconductors/insulating polymers is affected by molecular and process parameters;
For example, type and molecular weight (M)
The surface tension of the insulating polymer, the surface tension of each component and substrate, and the rotation speed and time.
At the same time, the spin effect-
The coating time for OFET properties has not been extensively studied.
In most articles that report a solution survey --
After processing ofet, depending on the volatility of the solvent used, the rotation time varies from 3 to 120 s. Field-
Semi-dynamic effect movement
Crystal polymer semiconductor can be improved by controlling spin
Due to molecular orientation and π-
By controlling the crystalline speed generated by residual solvents after spin, the π stacking interaction of binding molecules can be enhancedcoating.
Na, for example.
The residual solvent was investigated in spin-
Polysulfide films are cast on the electrical properties of ofet.
They found the best amount of residual solvent after rotation
The coating for a few seconds enhances the molecular order of the poly-sulfur film, resulting in a high field-Effect mobility. In small-
Molecular Semiconductor/insulating polymer mixture, controlled spin-
Casting mixed film is also important for inducing vertical phase
Separation to achieve high control of crystalline small molecule compound semiconductors
Electrical performance of Ofet, such as mobility, on-
Current and threshold voltages are affected by gas molecules, biomes and chemical analytes near the interface between the semiconductor and the gatedielectric.
Here, the analyte acts as an agent for auxiliary charge transfer or a trap for suppressing charge migration.
In particular, gas molecules affect charge transfer due to their dipolar properties.
Because gas molecules should penetrate the semiconductor layer to reach the interface between the semiconductor and the gate
Dielectric Properties, the microstructure of the semiconductor layer is critical for the sensing performance of OFET gas sensors.
For example, it is recommended to use a porous organic semiconductor film as an active layer, because the porous microstructure allows the analyte to reach the active layer more efficiently and reduces the time of the adsorption/de-adsorption process with the active layer of the device.
Therefore, from the perspective of the gas sensor, this is unfavorable when the organic semiconductor film is thick and uniform.
In this work, 6, 13-bis(
Three C-based milk thistle)pentacene (TIPS-pentacene)
Used as an organic semiconductor due to its high field
Impact mobility and solutionsprocessability.
In addition, polystyrene (PS)
As an insulating polymer, there is no polar base.
Separation and structural development of TIPS
Preparation of pentacene/PS mixture by changing spin
Coating time of mixed solution.
Crystalline mode of TIPS-
Five benzene in the prompt-
The pentacene/PS mixture was examined considering the amount of residual solvents in the tip-
Rotating pentacene/PS mixed filmcasting.
The electrical and gas sensing properties of FET devices are related to the microstructure of the mixed film, which is controlled by two different crystalline modes.