JP3045224B2 - Organic semiconductor, photoelectric conversion element and electrochromic display element using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the photovoltaic cells, optical sensors, Fang which can be used in organic transistors,
Relates to an organic semiconductor consisting of itself of a thin film of aromatic amine compounds, further, it self of such aromatic amine compound
The present invention relates to a photoelectric conversion element and an electrochromic display element using an organic semiconductor formed of a thin body film .

[0002]

2. Description of the Related Art Conventionally, as an organic semiconductor, typically, a thin film of polyvinyl carbazole which is reduced in resistance by doping or a phthalocyanine dispersed in an organic polymer as a binder and formed into a thin film is used. It has been known. Since the polyvinyl carbazole itself has a high volume resistance of 10 ¹⁴ to 10 ¹⁵ cm · Ω, it is physically and physically difficult to use for an electronic device.
It is necessary to reduce the resistance by chemical or electrochemical doping. On the other hand, since the phthalocyanine cannot be thinned by itself, the use of a binder is indispensable for thinning.

[0003]

SUMMARY OF THE INVENTION The present inventors have conducted intensive studies to solve the problems in the conventional organic semiconductor as described above, and as a result, have found that certain aromatic amine compounds have an ionization potential. And low resistance in an undoped state, and can be formed into a thin film without using a binder by itself.
It is another object of the present invention to provide an organic semiconductor comprising a thin film of an aromatic amine compound itself .
And an object thereof is to provide a photoelectric conversion element and electrochromic display device using an organic semiconductor formed of a thin film of its own aromatic amine compound Una.

[0004]

The organic semiconductor according to the present invention has the general formula (I)

[0005]

Embedded image

Wherein R is independently an aryl group or
Represents an aralkyl group . )).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the above general formula (I), R
Preferably denotes a phenyl group, a tolyl group, an aryl group having 6 to 18 carbon atoms such as naphthyl group, a benzyl group, an aralkyl group having 6 to 20 carbon atoms naphthylmethyl.

Accordingly, specific examples of particularly preferred organic semiconductors according to the present invention include, for example , 4,4 ', 4 "-tris (phenyltolylamino) triphenylamine and 4,4', 4" -tris (diphenylamino). Triphenylamine, 4,4 ',
Examples thereof include those formed of a thin film of itself such as 4 "-tris (benzylphenylamino) triphenylamine.

Among the above aromatic amine compounds, those in which R is an aryl group or an aralkyl group include, for example, 4,4 ′,
An excess of the aromatic secondary amine corresponding to 4 "-triiodotriphenylamine is optionally added in the presence of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide and a catalyst such as copper. After reacting in an organic solvent, the reaction product is dissolved in the organic solvent, the catalyst is filtered off,
It can be obtained by separating and purifying the reaction product by column chromatography using an appropriate eluate.

The aromatic amine compounds thus obtained are all stable compounds, have low resistance without doping, and can be formed into a thin film by a solvent casting method. Therefore, the thin film made of the aromatic amine compound itself can be used, for example, as an organic semiconductor in a Schottky solid-state photoelectric conversion element.

The above aromatic amine compounds all exhibit stable oxidation-reduction reactivity, and may be used together with a suitable electrolyte such as tetraammonium perchlorate and, if necessary, a binder such as polyacrylic acid. By forming a thin film on a transparent electrode such as Nesa glass and disposing a back electrode on the thin film, it can be used as a complete solid-state electrochromic display device.

[0012]

As is evident from the foregoing description, the organic semiconductor <br/> is according to the invention, a low ionization potential, a low resistance in a non-doping state, the which can be a thin film without using a binder by itself Aromatic amination represented by general formula (I)
It is composed of a thin film of the compound itself and can be suitably used for, for example, a photoelectric conversion element or an electrochromic display element.

[0013]

The present invention will be described below with reference to Reference Examples and Examples, but the present invention is not limited to these Examples.

Reference Example 1 (Synthesis of 4,4 ', 4 "-tris (diphenylamino) triphenylamine) 6.23 g of 4,4', 4" -triiodotriphenylamine, 10.1 g of diphenylamine, and hydroxylation Potassium 6.8g, copper powder
4.5 g and 10 mL of decalin in a nitrogen atmosphere at 160 ° C.
After reacting for 6 hours, the reaction mixture was dissolved in benzene, and insolubles were filtered off. The obtained benzene solution was treated by silica gel column chromatography to separate the reaction product as a pale yellowish white solid, which was recrystallized from benzene to give 3.0 g of the title compound (yield: 40.2). %). FIG. 1 shows the infrared absorption spectrum.

Melting point: 275-276 ° C. Mass spectrometry (parent peak): 746 (m / e) Elemental analysis (as C ₅₄ H ₄₂ N ₄ ):

Reference Example 2 Synthesis of 4,4 ′, 4 ″ -tris (phenyl-m-tolylamino) triphenylamine 6.23 g of 4,4 ′, 4 ″ -triiodotriphenylamine, 3-phenyl-m After reacting 11.0 g of tolylamine, 6.8 g of potassium hydroxide, 4.5 g of copper powder and 10 mL of decalin for 7 hours at 170 ° C. in a nitrogen atmosphere, the reaction mixture was dissolved in benzene and insolubles were filtered off. . The obtained benzene solution was treated by silica gel column chromatography to separate the reaction product, which was recrystallized from benzene / hexane to give 3.7 g of the title compound (yield: 46.4%). Was obtained as white columnar crystals. FIG. 2 shows the infrared absorption spectrum.

Melting point: 210 to 211 ° C. Mass spectrometry (parent peak): 788 (m / e) Elemental analysis (as C ₅₇ H ₄₈ N ₄ ):

[0018] Figure 3 DSC Chiyato of this compound
Shown in The first scan has a peak at 206 ° C. indicating endotherm due to melting when the temperature is raised, but no peak occurs when the temperature is lowered. In the second scan, a broad exothermic peak is observed around 170 ° C. and an endothermic peak is observed at 206 ° C. as the compound is crystallized.

Reference Example 3 (Synthesis of 4,4 ', 4 "-tris (benzylphenylamino) triphenylamine) 6.23 g of 4,4', 4" -triiodotriphenylamine and 11.0 g of benzylphenylamine , Potassium hydroxide 6.8
g, 4.5 g of copper powder and 10 mL of decalin were reacted in a nitrogen atmosphere at 160 ° C. for 12 hours, then the reaction mixture was dissolved in benzene, and insolubles were filtered off. After the benzene was distilled off from the obtained benzene solution, the residue was eluted by neutral alumina column chromatography with tetrahydrofuran and recrystallized from benzene / ethanol to obtain 1.1 g of the title compound (yield: 15.0). %) As white needle-like crystals. FIG. 4 shows the infrared absorption spectrum.

Melting point: 200-203 ° C. Mass spectrometry (parent peak): 788 (m / e) Elemental analysis (as C ₅₇ H ₄₈ N ₄ ):

Next, examples of a photoelectric conversion element and an electrochromic display element using the aromatic amine compound obtained as described above as an organic semiconductor will be described.

Example 1 4,4 ', 4 "-Tris (phenyl-m-tolylamino) triphenylamine was dissolved in benzene, applied on a Nesa glass plate, and dried by heating to obtain a thin film having a thickness of 20 μm. As shown in FIG. 5 , aluminum was vapor-deposited on the thin film 1 to form an electrode 2, and lead wires 4 and 5 were connected to the aluminum electrode and the Nesa glass 3 with a silver paste, and thus shot. A key-type solid-state photoelectric conversion element was manufactured.

In this device, 4,4 ', 4 "-tris (phenyl-m-tolylamino) triphenylamine functions as a p-type semiconductor, and a Schottky barrier is formed at the interface with the aluminum electrode. For this reason, when a positive voltage was applied to a Nesa glass electrode with respect to an aluminum electrode in a dark place, a clear rectification characteristic was obtained in the forward direction, and the rectification ratio at ± 3 V was 25. 6 shows the current-voltage characteristics when the device was irradiated with light of 366 nm, with a fill factor of 0.25 and a conversion efficiency of 0.08% for light transmitted through the aluminum electrode.

EXAMPLE 2 A cyclic voltammogram of 4,4 ', 4 "-tris (diphenylamino) triphenylamine is shown in FIG. 7 , and 4,4', 4" -tris (phenyl-m-tolylamino) )
FIG. 8 shows the cyclic voltammogram of triphenylamine. Acetonitrile, t-BuN ⁺ ClO ₄ as a supporting electrolyte as solvent ^- the use, scan rate 10
0 mV / sec. The potential is relative to SCE.

As apparent from the above, the organic semiconductor comprising the aromatic amine compound according to the present invention exhibits very stable oxidation-reduction reactivity, and forms an electrochromic display element as described above. These elements exhibit a green or purple color when energized, and are decolored when energized in the opposite direction.

[Brief description of the drawings]

FIG. 1 shows the infrared absorption spectrum of 4,4 ′, 4 ″ -tris (diphenylamino) triphenylamine.

FIG. 2 shows an infrared absorption spectrum of 4,4 ′, 4 ″ -tris (phenyl-m-tolylamino) triphenylamine.

FIG. 3 shows a DSC chart of 4,4 ′, 4 ″ -tris (phenyl-m-tolylamino) triphenylamine.

FIG. 4 shows an infrared absorption spectrum of 4,4 ′, 4 ″ -tris (benzylphenylamino) triphenylamine.

FIG. 5 generally shows a cross-sectional view of a Schottky solid-state photoelectric conversion element.

FIG. 6 is a graph showing current-voltage when a Schottky solid-state photoelectric conversion element obtained using a thin film of 4,4′-diphenyl-4 ″ -m-tolylaminotriphenylamine was irradiated with light at 366 nm. Show characteristics.

FIG. 7 shows a cyclic voltammogram of 4,4 ′, 4 ″ -tris (diphenylamino) triphenylamine.

FIG. 8 shows a cyclic voltammogram of 4,4 ′, 4 ″ -tris (phenyl-m-tolylamino) triphenylamine.

[Explanation of symbols]

 1. Thin film, 2. Electrode, 3. Nesa glass.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-77855 (JP, A) Chem. Abstr. , (1973) vol. 79 abstract No. 11631p (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 211/54 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A compound of the general formula (Wherein, R is each independently an aryl group or an aralkyl
Represents a group . It self aromatic amine compounds represented by)
Organic semiconductor consisting of a thin film of the body . 2. A compound of the general formula (Wherein, R is each independently an aryl group or an aralkyl
Represents a group . It self aromatic amine compounds represented by)
A photoelectric conversion element characterized in that a thin film of a body is used as an organic semiconductor. 3. A compound of the general formula (Wherein, R is each independently an aryl group or an aralkyl
Represents a group . It self aromatic amine compounds represented by)
An electrochromic display element, wherein a thin film of a body is used as an organic semiconductor.