CN104777359A - Method for measuring organic semi-conductor state density - Google Patents

Abstract

The invention discloses a method for measuring organic semi-conductor state density. The method for measuring the organic semi-conductor state density comprises the first step of measuring the Seebeck coefficient of an organic semi-conductor material; the second step of choosing a state density function based on the features of the organic semi-conductor material; the third step of calculating the Seebeck coefficient value of the organic semi-conductor material through the seepage theory; the fourth step of extracting the state density width of the material; the fifth step of extracting the state density of the organic semi-conductor material. According to the method for measuring the organic semi-conductor state density, based on the Seebeck coefficient value under the material temperature varying and the carrier transition theory, through the theory and experiment combined method, the state density of the organic semi-conductor material is measured, the theoretical guidance is provided for the micro-physical mechanism of analyzing organic semi-conductor materials, the method can be directly used for analyzing carrier transportation characteristics of the organic semi-conductor materials, and therefore the guidance is provided for manufacturing high performance organic semi-conductor apparatuses.

Description

Measure the method for organic semiconductor state density

Technical field

The invention belongs to the technical field of organic semiconductor device, particularly relate to a kind of method measuring organic semiconductor state density.

Background technology

Organic semiconducting materials have flexibility, transparent, low cost, can the advantage such as large area manufacture, have broad application prospects.In past 20 years, organic semiconducting materials achieves huge progress, and the various device based on organic semiconducting materials continues to bring out, such as OTFT, organic solar batteries, organic field effect tube etc.

In organic semiconductor field, charge transmission plays a decisive role for organic semiconductor device performance, and determines that the key factor of charge transmission is power spectrum, is also referred to as state density (Density of states is called for short DOS).In statistical mechanics and Condensed Matter Physics, state density or the density of states be near a certain energy between per unit energy range in the number of microstate.For the material with complete ordered crystal structure, its state density can be obtained by first-principles calculations, but for amorphous organic semiconducting materials, method unique is at present by comparative experiments and the DOS method of use experience is carried out matching and obtained its state density.

Summary of the invention

From the above mentioned, the object of the invention is to according to the analysis to Related Research Domain present situation, based on the value of the Seebeck coefficient under material alternating temperature and the transition theory of charge carrier, a kind of method detecting organic semiconducting materials state density is proposed, the method is simple to operate, can be widely used in the various organic semiconducting materials with amorphous structure.

For this reason, the invention provides a kind of method measuring organic semiconducting materials state density, comprising: step 1, measure the Seebeck coefficient of organic semiconducting materials; Step 2, based on the feature of organic semiconducting materials, selects a kind of state density function; Step 3, calculates the Seebeck coefficient value of organic semiconducting materials by seepage theory; Step 4, extracts the state density width of material; Step 5, extracts the state density of organic semiconducting materials.

Wherein, step 1 comprises step further: use four end in contact methods to measure the resistance value of organic semiconducting materials; To resistance value be recorded convert to the temperature value of organic semiconducting materials; Measure thermal voltage; Adopt formula S=Δ V/ Δ T to calculate the Seebeck coefficient of organic semiconducting materials, wherein Δ V is the changing value of thermal voltage, and Δ T is temperature change value.

Wherein, by using stepping temperature scanning method and the resistance value on temperature value of measuring acquisition under isothermal conditions to correct.

Wherein, the state density function of step 2 is the gauss' condition density function that formula (1) represents wherein, N _tthe number of states of representation unit volume, E represents the energy after normalization, σ ^*=σ/k _bt represents the width of state density, k _brepresent Boltzmann constant.

Wherein, step 3 comprises further:

According to seepage theory, Peltier coefficient Π is calculated by following formula (3) and obtains:

Π＝∫E _iP(E _i)dE _i， (3)，

P (E in formula _i) represent that in energy space, one has ENERGY E _ithe probability of position, can pass through following formula (4) and obtain

$P\left(E_i\right)=\frac{g\left(E_i\right)P_1\left(Z_m\right|E_i)}{{\∫}_{-E_m}^{E_m}g\left(E_i\right)P_2\left(Z_m\right|E_i)d{E}_i}---\left(4\right)$

G (E in formula _i) state density of representation unit volume, E _mrepresent maximum potential energy, P ₁(Z _m| E _i) represent from potential energy E _isecond little resistance probability, its value is less than maximum resistance, calculates obtain by following formula (5),

P ₁(Z _m|E _i)＝1-exp[-P(Z _m|E _i)][1+P(Z _m|E _i)] (5)，

P (Z in above formula _m| E _i) represent the density be with;

According to Kelvin-Onsager relation, by formula (1), (3), (4), (5) are substituted into following formula (2) and then can calculate theoretical Seebeck coefficient value:

$S=\frac{\mathrm{\Π}}{T}---\left(2\right)$

In formula, Π is the Peltier coefficient of formula (3), and T is temperature.

Wherein, P (Z _m| E _i) value obtains by the following formula of simultaneous solution (6), (7) and (8)

$S_{\mathrm{ij}}=2\mathrm{\α}{R}_{\mathrm{ij}}+\frac{|E_i-E_f|+|E_j-E_f|+|E_i-E_j|}{2k_{B}T}---\left(6\right)$

P(Z _m|E _i)＝∫4πR _ij ²g(E _i)g(E _j)dR _ijdE _idE _jθ(S _c-S _ij) (7)

P(Z _m|E _i)＝B _cP _s＝B _c∫g(E)dEθ(S _ck _BT-|E-E _f|) (8)

Wherein, α represents the inverse of grating constant, R _ijrepresent the space length of position i and position j, E _frepresent Fermi level, E _iand E _jrepresent the energy of position i and position j respectively, k _brepresent Boltzmann constant, B _crepresent seepage parameters (being generally 2.8), T is temperature, and g (E) is gauss' condition density, and S is Seebeck coefficient.

Wherein, step 4 comprises further: the width value σ selecting suitable state density; The Seebeck coefficient value S that material changes with carrier concentration is gone out by changing the size analog computation of temperature T; The experiment value that Seebeck coefficient theoretical value under different temperatures step 3 calculated and step 1 record compares mutually; If theoretical value and experiment value relative error magnitudes are less than 5%, then selected σ value is the width of the state density of organic semiconducting materials, if the error of theoretical value and experiment value is greater than 5%, σ value need be reselected and Seebeck coefficient value under recalculating different temperatures, repeat above step until theoretical value and experiment value relative error magnitudes are less than 5%.

Wherein, state density width cs step 4 obtained, the number of states Nt of unit volume and temperature T substitute into the state density that formula (1) obtains organic semiconducting materials.

According to the method for measurement organic semiconductor state density of the present invention, based on the value of the Seebeck coefficient under material alternating temperature and the transition theory of charge carrier, the state density of organic semiconducting materials is detected by the theoretical method combined with experiment, for the microphysics mechanism analyzing organic semiconducting materials provides theoretical direction, the carrier transport characteristic analyzing organic semiconducting materials can be directly used in, thus provide guidance for manufacturing high performance organic semiconductor device.

Accompanying drawing explanation

Technical scheme of the present invention is described in detail referring to accompanying drawing, wherein:

Fig. 1 is the skeleton view according to measurement structure of the present invention;

Fig. 2 shows the result changed with carrier concentration respectively by experiment and the theoretical IDTBT material Seebeck coefficient at different temperatures obtained;

Fig. 3 shows the IDTBT material state density at room temperature of acquisition;

Fig. 4 shows the result changed with carrier concentration respectively by experiment and the theoretical PBTTT material Seebeck coefficient at different temperatures obtained;

Fig. 5 shows the PBTTT material state density at room temperature of acquisition;

Fig. 6 shows the process flow diagram according to measuring method of the present invention.

Embodiment

Describe feature and the technique effect thereof of technical solution of the present invention in detail in conjunction with schematic embodiment referring to accompanying drawing, disclosing can efficient, stable, the method for measuring organic semiconducting materials state density at low cost.It is pointed out that structure like similar Reference numeral representation class, term " first " used in the application, " second ", " on ", D score etc. can be used for modifying various device architecture or manufacturing process.These modify the space of not hint institute's modification device architecture or manufacturing process unless stated otherwise, order or hierarchical relationship.

As shown in Figure 1, be the skeleton view of the measurement structure according to measurement organic semiconducting materials Seebeck coefficient of the present invention.It comprises dielectric substrate 11, the gate electrode 12 in dielectric substrate 11, the gate insulation layer 13 on gate electrode 12, on gate insulation layer 13 and across the organic semiconductor active layer (not adopting Reference numeral to mark in figure) of gate insulation layer 13 and gate electrode 12.Multiplely (be four in a preferred embodiment of the invention, in addition also can be more six, eight, ten, 12 etc.) temperature sensor connecting line 14,15,16,17 is arranged in dielectric substrate 11, be connected to the source region of machine semiconductor active layer and drain region (be such as source area on the left of grid 12 in Fig. 1, right side is such as drain region) and it be connected to further the temperature sensor (not shown) of peripheral hardware.And preferably, multiple temperature sensor connecting line is used as the source-drain electrode of OTFT.Further preferably, multiple temperature sensor connecting line is even number and symmetrical.Multiple temperature control line 18,19 is connected to a part for multiple temperature sensor connecting line and is connected to temperature controller (the such as voltage source and/or current source of peripheral hardware further, not shown, flow through the electric current of active layer and/or voltage by regulating and change heating/type of cooling, and then control the temperature of active layer), in a preferred embodiment of the invention for being positioned at the temperature sensor connecting line 15,17 of the same side.

Wherein, dielectric substrate 11 material can be the Semiconductor substrate with surface insulation layer, such as, with the thick SiO of 200nm ₂the Si substrate of insulation course, such as SOI substrate also can be the substrate that AlN, sapphire, glass, plastics etc. are all made up of insulating material.Dielectric substrate 11 thickness is such as 1mm ~ 10mm.

Wherein, gate electrode 11, temperature sensor connecting line 14/15/16/17, temperature control line 18/19 material can be: the metal being selected from Pt, Au, W, Pd, Cu, Ag, Ni, Al, Ti, Ta, Co, Ir, Zn, the alloy of these metals, the conductive nitride (such as TiN, TaN, WN etc.) of these metals, conductive oxide (the such as IrO of these metals _x, ITO, IZO, IGZO, AZO etc.), or the conductive silicide of these metals (such as NiSi, PtSi, TiSi, WSi, CoSi etc.).Preferably, the conductivity of temperature sensor connecting line 14/15/16/17 be greater than gate electrode 11, temperature control line 18/19 conductivity (correspondingly, its resistivity is less), and the thermal conductivity of gate electrode 11, temperature control line 18/19 is greater than the thermal conductivity (correspondingly, its thermal resistivity is less) of temperature sensor connecting line 14/15/16/17.In a preferred embodiment of the invention, gate electrode, temperature control line are that the materials such as Pt, Au, Ag, Cu (are preferably the alloy with Cu, or at least comprise the sublayer of Cu), and temperature sensor connecting line is Pt, Au, Ag material, so can effectively improve thermometric accuracy.

Wherein, the width (yardstick along OTFT channel region bearing of trend) of gate electrode 11 is 1mm ~ 2mm, and thickness is 100nm ~ 500nm.The width (yardstick along perpendicular to OTFT channel region bearing of trend) of temperature sensor connecting line 14/15/16/17, temperature control line 18/19 can be 1mm ~ 2mm, and thickness is 100nm ~ 500nm.Between the temperature sensor connecting line of phase the same side (such as all connecting source electrode or drain electrode) (such as 16,17, or 14,15), spacing is 10 ~ 500 μm.Between the temperature control line 18,19 being connected to not homonymy temperature sensor connecting line (such as 15 and 17), spacing is 100nm ~ 500 μm.

Wherein, the material of organic semiconductor active layer is organic semiconductor to be measured, such as comprise there is specified molecular weight conjugated polymers organism, such as conjugated oligomer, polynuclear aromatics (as polyacene (pentacene), polyenoid); Such as phthalandione prussiate, such as CuPc, F ₁₆cuPc, NiPc, CoPc, ZnPc, H ₂pc, TiOPc, VOPc, F ₁₆znPc, pentacene; Such as two phthalein mountain valley with clumps of trees and bamboo metal, H ₂nc, CoNc, CuNc, ZnNc, NiNc etc.; Such as organic pyrene oxygen radical semiconductor layer, such as 2-pyrenyl-4,4,5,5-tetramethyl imidazoline-1-oxygen base free radical; Such as quinacridone derivative; Such as C ₆₀etc..Organic semiconductor active layer length (such as along channel region bearing of trend) is 1mm ~ 10mm, and width (such as perpendicular to channel region bearing of trend, such as, with grid intersection region) is 100 μm ~ 1mm, and thickness is 500 ~ 1000nm.

Wherein, gate insulation layer 13 is monox, silicon nitride, silicon oxynitride, other low-k materials, other high-g value etc.In a preferred embodiment of the invention, gate insulation layer 13 is polymethylmethacrylate (PMMA), so to improve flexibility, light transmission and the bond strength with organic semiconductor active layer, improve temperature stability, improve organic semiconducting materials Seebeck coefficient measuring accuracy further.

The preparation method measuring structure is as follows:

First, such as, adopt electron beam evaporation, chemical vapor deposition, pulsed laser deposition, ald or magnetically controlled sputter method, dielectric substrate 11 is formed gate electrode 12.The material of dielectric substrate 11, gate electrode 12 and size are as previously mentioned.

Secondly, such as adopt the methods such as electron beam evaporation, chemical vapor deposition, pulsed laser deposition, ald, magnetron sputtering, spraying, serigraphy, gel-sol, gate electrode 12 is formed gate insulation layer 13.As previously mentioned, size is preferably at least greater than gate electrode 12 so that cover completely in channel region or wrap up gate electrode 12 to gate insulation layer 13 material.

Then, gate insulation layer 13 forms organic semiconductor active layer, such as, adopt the method for mechanical stripping or chemical vapor deposition.

Then, such as adopt electron beam evaporation, chemical vapor deposition, pulsed laser deposition, ald or magnetically controlled sputter method, dielectric substrate 11 is formed the multiple temperature sensor connecting lines 14,15,16,17 being connected to the source-drain area of organic semiconductor active layer.Connecting line is distributed in the both sides of gate electrode 12.The material of connecting line 14 ~ 17 and size are as previously mentioned.

Finally, such as adopt electron beam evaporation, chemical vapor deposition, pulsed laser deposition, ald or magnetically controlled sputter method, dielectric substrate 11 is formed the multiple temperature control lines 18,19 being connected to the temperature sensor connecting line be connected with source-drain area respectively, makes temperature control line also be distributed in the both sides of gate electrode 12 and be positioned at the same side of temperature sensor connecting line.Such as, temperature control line 18 is connected to the temperature sensor connecting line 17 be connected with source region, and temperature control line 19 is connected to the temperature sensor connecting line 15 be connected with drain region.The material of temperature control line 18,19 and size are as previously mentioned.

Preferably, identical material and technology one step can be adopted to produce temperature sensor connecting line and temperature control line.

The measurement structure that preparation technology described above finally obtains as shown in Figure 1.

According to measurement organic semi-conductor state density of the present invention method as shown in Figure 6, specifically comprise the following steps:

The Seebeck coefficient of step 1, measurement organic semiconducting materials (material of active layer as above).

In the application method that the Seebeck coefficient of measurement structure to the organic semiconductor active layer material of OTFT is measured as shown in Figure 1, four end in contact methods are preferably adopted to measure temperature and the voltage of samples.

Particularly, first use the resistance value of current source (such as Keithley 6221 type) measuring tempeature sensor connect lines, such as, four of measuring instrument input end clips or probe are electrically connected to four temperature sensor connecting lines 14 ~ 17 respectively.

Then, with temperature-coefficient of electrical resistance instrument, the resistance value measured is converted to temperature value T, such as measure OTFT in enormous quantities in advance, record the mutual relationship between the resistance value of organic semiconductor active layer and temperature value, or the resistance v. temperature mutual relationship that reading writes in advance from the storer (such as ROM) of testing tool equipment, but convert the temperature value of OTFT to be measured to according to the distributed resistance numerical value recorded by multiple temperature sensor connecting line.

Then, the thermal voltage V of measuring tempeature sensor connect lines, such as, use 2182A type nanovolt meter, four of measuring instrument input end clips or probe be electrically connected to four temperature sensor connecting lines 14 ~ 17 respectively.

Subsequently, the Seebeck coefficient of following formula (0) calculation sample is adopted:

$S=\frac{\mathrm{\ΔV}}{\mathrm{\ΔT}}---\left(0\right)$

Wherein Δ V is the changing value of the thermal voltage measuring the temperature sensor connecting line obtained, and Δ T is the changing value being converted to temperature value by resistance value, and S represents thermal voltage variation with temperature speed (such as being obtained by differential derived function).

Preferably, by using stepping temperature scanning method and measuring the resistance value of acquisition under isothermal conditions thus correct temperature value.

Preferably, for ensureing the accuracy measured, under need being placed in high vacuum condition to the OTFT measurement comprising above-mentioned measurement structure, such as vacuum tightness is greater than (also namely test chamber internal gas pressure is less than) 1.0 × 10 ^-4pa.

In a preferred embodiment of the invention, first, electron beam evaporation process is utilized, with the thick SiO of 200nm ₂insulation course Si substrate on, the Au film of magnetron sputtering 200nm is as metal gate electrode; Then, utilize chemical deposition on metal gate electrode, deposit PMMA insulation course; Then adopt chemical vapour deposition technique that organic material is transferred to PMMA insulation course; Then utilize magnetically controlled sputter method to deposit in the side of organic material the temperature sensor connecting line that four thickness are 200nm, it is spaced apart 50 μm; Finally prepare with magnetron sputtering method the metal wire for controlling material temperature that two thickness are 200nm.After preparing device, use the resistance value of Keithley 6221 type current source measuring tempeature sensor connect lines, then with temperature-coefficient of electrical resistance, the resistance value measured is converted to temperature value; Use 2182A type nanovolt measurement amount temperature sensor connect lines thermal voltage; The Seebeck coefficient of material is calculated finally by above-mentioned formula (1).

In addition, although the OTFT that illustrations 1 discloses bottom grating structure measures structure, the application goes for the OTFT of top gate structure too, and such as gate electrode, gate insulation layer are distributed in organic semiconductor active layer.

Step 2, selection mode density function.

Based on the feature of organic semiconducting materials, the distribution situation will gauss' condition density function being selected to represent charge carrier in a preferred embodiment of the invention, gauss' condition density g (E) is

$g\left(E\right)=\frac{N_t}{\sqrt{2\mathrm{\π}}{\mathrm{\σ}}^{*}}\exp (-\frac{E^2}{{2\mathrm{\σ}}^{*2}})---\left(1\right)$

N in formula (1) _tthe number of states of representation unit volume, E represents the energy after normalization, σ ^*=σ/k _bt represents the width of state density, k _brepresent Boltzmann constant.

Step 3, Seebeck coefficient value by seepage theory Calculating material.

First according to Kelvin-Onsager relation, Seebeck coefficient S can be expressed as:

$S=\frac{\mathrm{\Π}}{T}---\left(2\right)$

In formula, Π is Peltier coefficient, and T is temperature.

According to seepage theory, Peltier coefficient Π is calculated by following formula and obtains:

Π＝∫E _iP(E _i)dE _i， (3)

According to P (E in formula _i) represent that in energy space, one has ENERGY E _ithe probability of position, can be obtained by following formula

$P\left(E_i\right)=\frac{g\left(E_i\right)P_1\left(Z_m\right|E_i)}{{\∫}_{-E_m}^{E_m}g\left(E_i\right)P_2\left(Z_m\right|E_i)d{E}_i}---\left(4\right)$

G (E in formula _i) state density of representation unit volume, E _mrepresent maximum potential energy, P ₁(Z _m| E _i) represent from potential energy E _isecond little resistance probability, its value is less than maximum resistance, calculates obtain by following formula,

P ₁(Z _m|E _i)＝1-exp[-P(Z _m|E _i)][1+P(Z _m|E _i)] (5)

P (Z in above formula _m| E _i) represent the density be with.Corresponding P (Z _m| E _i) value obtains by simultaneous solution formula (6), (7) and (8)

$S_{\mathrm{ij}}=2\mathrm{\α}{R}_{\mathrm{ij}}+\frac{|E_i-E_f|+|E_j-E_f|+|E_i-E_j|}{2k_{B}T}---\left(6\right)$

P(Z _m|E _i)＝∫4πR _ij ²g(E _i)g(E _j)dR _ijdE _idE _jθ(S _c-S _ij) (7)

P(Z _m|E _i)＝B _cP _s＝B _c∫g(E)dEθ(S _ck _BT-|E-E _f|) (8)

Wherein, α represents the inverse of grating constant, R _ijrepresent the space length of position i and position j, E _frepresent Fermi level, E _iand E _jrepresent the energy of position i and position j respectively, k _brepresent Boltzmann constant, B _crepresent seepage parameters (being generally 2.8), T is temperature, and g (E) is gauss' condition density, and S is Seebeck coefficient.

Finally, by formula (1), (3), (4), (5) are substituted into formula (2) and then can calculate theoretical Seebeck coefficient value.

The state density width of step 4, extraction material.

First select suitable σ value (width of state density), such as, estimate according to the existing measured value of similar materials, or obtain predicted value by test short run sample, the Seebeck coefficient value that material changes with carrier concentration is gone out by changing the size analog computation of temperature, and Seebeck coefficient S under the different temperatures that theory calculate is gone out with test the value recorded and compare mutually, when calculated value conforms to experiment value (here theoretical value and the relative error magnitudes of experiment value are less than 5% representation theory value conform to experiment value), then selected σ value is the width of the state density of material, error as theoretical value and experiment value is greater than 5%, σ value need be reselected and Seebeck coefficient value under recalculating different temperatures, and then the theoretical value calculated and experiment value are compared, until error is between the two less than 5%.

The state density of step 5, extraction organic semiconducting materials

The width cs of the state density that step 4 obtains, the number of states N of unit volume _tthe state density that formula (1) can obtain organic semiconducting materials is substituted into temperature T.

Embodiment one

Using IDTBT (indacenodithiophene-co-benzothiadiazole) material as an embodiment.First by the value that Seebeck coefficient under the different temperatures of four end in contact methods measurement IDTBT changes with carrier concentration, result as shown in Figure 2.Then to utilize in the present invention make the theoretical method stated calculate this material value of changing with carrier concentration of Seebeck coefficient at different temperatures, calculating selected parameter is: N _t=7.6 × 10 ²⁶m ³, α=0.1nm, E _f=-40k _bt, σ=1.2k _bt.Be 3% finally by the relative difference comparing theoretical value and experiment value, coincidence loss requirement.Therefore, the width of the state density of IDTBT material is σ=1.2k _bt.T=300K, σ=1.2k _bt and N _t=7.6 × 10 ²⁶m ³substitute into the state density that formula (1) calculates IDTBT material.Figure 2 shows that the result of Seebeck coefficient theoretical value and experiment value, Figure 3 shows that the state density obtaining organic semiconductor IDTBT.

Embodiment two

With PBTTT (polymerpoly (2,5-bis (3-alkylthiophen-2-yl) thieno [3,2-b] thiophene)) material as an embodiment.First by the value that Seebeck coefficient under four end in contact methods measurement PBTTT different temperatures changes with carrier concentration, result as shown in Figure 3.Then to utilize in the present invention make the theoretical method stated calculate this material value of changing with carrier concentration of Seebeck coefficient at different temperatures, calculating selected parameter is: N _t=8.9 × 10 ²⁶m ³, α=0.22nm, E _f=-40k _bt, σ=3.5k _bt; Be 5% finally by the relative difference comparing theoretical value and experiment value, coincidence loss requirement.Therefore, the width of PBTTT materials behavior density is 3.5k _bt.T=300K, σ=3.5k _bt and N _t=8.9 × 10 ²⁶m ³substitute into the state density that formula (1) calculates PBTTT material.Figure 4 shows that the result of Seebeck coefficient theoretical value and experiment value, Figure 5 shows that the state density obtaining organic semiconductor PBTTT.

Beneficial effect

As can be seen from technique scheme, the present invention has following beneficial effect: 1, in the present invention, a kind of method combined with experiment by theory can detect the state density of organic semiconducting materials, and the state density of acquisition can provide theoretical direction for the microphysics mechanism analyzing organic semiconducting materials; 2, the state density extracted can be directly used in the carrier transport characteristic analyzing organic semiconducting materials, thus provides guidance for manufacturing high performance organic semiconductor device.

According to the method for measurement organic semiconductor state density of the present invention, based on the value of the Seebeck coefficient under material alternating temperature and the transition theory of charge carrier, the state density of organic semiconducting materials is detected by the theoretical method combined with experiment, for the microphysics mechanism analyzing organic semiconducting materials provides theoretical direction, the carrier transport characteristic analyzing organic semiconducting materials can be directly used in, thus provide guidance for manufacturing high performance organic semiconductor device.

Although the present invention is described with reference to one or more exemplary embodiment, those skilled in the art can know without the need to departing from the scope of the invention and make various suitable change and equivalents to device architecture or method flow.In addition, can be made by disclosed instruction and manyly may be suitable for the amendment of particular condition or material and not depart from the scope of the invention.Therefore, object of the present invention does not lie in and is limited to as realizing preferred forms of the present invention and disclosed specific embodiment, and disclosed device architecture and manufacture method thereof will comprise all embodiments fallen in the scope of the invention.

Claims (8)

1. measure a method for organic semiconducting materials state density, comprising:

Step 1, measures the Seebeck coefficient of organic semiconducting materials;

Step 2, based on the feature of organic semiconducting materials, selects a kind of state density function;

Step 3, calculates the Seebeck coefficient value of organic semiconducting materials under selected state density function by seepage theory;

Step 4, extracts the state density width of material;

Step 5, extracts the state density of organic semiconducting materials according to state density width.

2. method as claimed in claim 1, wherein, step 1 comprises step further:

Four end in contact methods are used to measure the resistance value of organic semiconducting materials;

To resistance value be recorded convert to the temperature value T of organic semiconducting materials;

Measure thermal voltage V;

Adopt formula S=Δ V/ Δ T to calculate the Seebeck coefficient of organic semiconducting materials, wherein Δ V is the changing value of thermal voltage, and Δ T is temperature change value.

3. method as claimed in claim 2, wherein, is corrected by the resistance value on temperature value using stepping temperature scanning method and measure acquisition under isothermal conditions.

4. method as claimed in claim 1, wherein, the state density function of step 2 is the gauss' condition density function that formula (1) represents wherein, N _tthe number of states of representation unit volume, E represents the energy after normalization, σ ^*=σ/k _bt represents the width of state density, k _brepresent Boltzmann constant.

5. method as claimed in claim 4, wherein, step 3 comprises further:

According to seepage theory, Peltier coefficient Π is calculated by following formula (3) and obtains:

∏＝∫E _iP(E _i)dE _i(3)，

P (E in formula _i) represent that in energy space, one has ENERGY E _ithe probability of position, can pass through following formula (4) and obtain

$P\left(E_i\right)=\frac{g\left(E_i\right)P_1\left(Z_m\right|E_i)}{{\∫}_{-E_m}^{E_m}g\left(E_i\right)P_2\left(Z_m\right|E_i)d{E}_i}---\left(4\right),$

G (E in formula _i) state density of representation unit volume, E _mrepresent maximum potential energy, P ₁(Z _m| E _i) represent from potential energy E _isecond little resistance probability, its value is less than maximum resistance, calculates obtain by following formula (5),

P ₁(Z _m|E _i)＝1-exp[-P(Z _m|E _i)][1+P(Z _m|E _i)] (5)，

P (Z in above formula _m| E _i) represent the density be with;

According to Kelvin-Onsager relation, by formula (1), (3), (4), (5) are substituted into following formula (2) and then can calculate theoretical Seebeck coefficient value:

$S=\frac{\mathrm{\Π}}{T}---\left(2\right)$

In formula, Π is the Peltier coefficient of formula (3), and T is temperature.

6. method as claimed in claim 5, wherein, P (Z _m| E _i) value obtains by the following formula of simultaneous solution (6), (7) and (8)

$S_{\mathrm{ij}}=2\mathrm{\α}{R}_{\mathrm{ij}}+\frac{|E_i-E_f|+|E_j-E_f|+|E_i-E_j|}{2k_{B}T}---\left(6\right)$

P(Z _m|E _i)＝∫4πR _ij ²g(E _i)g(E _j)dR _ijdE _idE _jθ(S _c-S _ij) (7)

P(Z _m|E _i)＝B _cP _s＝B _c∫g(E)dEθ(S _Ck _BT-|E-E _f|) (8)

Wherein, α represents the inverse of grating constant, R _ijrepresent the space length of position i and position j, E _frepresent Fermi level, E _iand E _jrepresent the energy of position i and position j respectively, k _brepresent Boltzmann constant, B _crepresent seepage parameters (being generally 2.8), T is temperature, and g (E) is gauss' condition density, and S is Seebeck coefficient.

7. method as claimed in claim 1, wherein, step 4 comprises further:

Select the width value σ of suitable state density;

The Seebeck coefficient value S that material changes with carrier concentration is gone out by changing the size analog computation of temperature T;

The experiment value that Seebeck coefficient theoretical value under different temperatures step 3 calculated and step 1 record compares mutually;

If theoretical value and experiment value relative error magnitudes are less than 5%, then selected σ value is the width of the state density of organic semiconducting materials, if the error of theoretical value and experiment value is greater than 5%, σ value need be reselected and Seebeck coefficient value under recalculating different temperatures, repeat above step until theoretical value and experiment value relative error magnitudes are less than 5%.

8. method as claimed in claim 4, wherein, the state density width cs that step 4 is obtained, the number of states N of unit volume _tthe state density that formula (1) obtains organic semiconducting materials is substituted into temperature T.