JP2011176233A - Organic photoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an organic photoelectric conversion element capable of obtaining a high open-circuit voltage. <P>SOLUTION: The organic photoelectric conversion element includes a pair of electrodes 2, 6, and an electron-donating layer 3 and an electron-accepting layer 4, arranged between the pair of electrodes 2, 6, wherein the electron-donating layer 3 contains a compound represented by general formula (1). Here, R1-R18 independently represent a hydrogen, halogen, alkyl group, alkoxy group, alkenyl group, aryl group, aralkyl group or heterocyclic group. R1 and R2, and R3 and R4 may form a ring through mutual bonding. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic photoelectric conversion element including an electron donating layer and an electron accepting layer made of an organic material between a pair of electrodes.

  Organic photoelectric conversion elements have advantages such as lower manufacturing energy costs and lower environmental impact of disposal compared to conventional photoelectric conversion elements using inorganic semiconductors. Yes.

  In an organic photoelectric conversion element, generally, a photoelectric conversion region composed of an electron donating layer made of an electron donating material and an electron accepting layer made of an electron accepting material is provided between an anode and a cathode. When the organic photoelectric conversion element is irradiated with light, light absorption occurs in the photoelectric conversion region, excitons are formed, carriers are separated, electrons pass through the electron-accepting layer to the cathode, and holes pass through the electron-donating layer. Move to the anode. Thereby, an electromotive force is generated between the anode and the cathode, and the electric power can be taken out by connecting an external circuit.

  In Non-Patent Document 1, an organic photoelectric conversion element having a conversion efficiency of 0.95% was obtained by using copper phthalocyanine (CuPc) as an electron donating material and using a perylene derivative as an electron accepting material. It has been reported.

  Non-Patent Document 2 reports that the conversion efficiency is improved to 3.6% by using fullerene as an electron-accepting material.

  Non-Patent Document 3 reports that the open circuit voltage could be increased to 0.91 V by using rubrene instead of copper phthalocyanine (CuPc) as the electron donating material.

  In patent document 1, it is proposed that an open circuit voltage, a short circuit current, and photoelectric conversion efficiency can be improved by using a perylene derivative as an electron-donating material.

  In Patent Documents 2 and 3, it is proposed to use an anthracene derivative as a low-molecular photoelectric conversion element material.

  On the other hand, for consumer use, an organic photoelectric conversion element capable of obtaining a high output voltage is required. In order to increase the output voltage in the conventional organic photoelectric conversion element, it is necessary to integrate the battery structure, and there is a problem that the structure and the process are complicated. In order to reduce integration or reduce the number of integration stages, an organic photoelectric conversion element having a high open-circuit voltage is required, and such an organic photoelectric conversion element is required.

JP 2008-135540 A JP 2009-177125 A JP 2009-266955 A

Appl.Phys.Lett., 48,183 (1986) Appl.Phys.Lett., 79,126 (2001) J.J.Appl.Phys., 45, L995 (2006)

  The objective of this invention is providing the organic photoelectric conversion element from which a high open circuit voltage is obtained.

  The organic photoelectric conversion element of the present invention is an organic photoelectric conversion element comprising a pair of electrodes, an electron donating layer and an electron accepting layer disposed between the pair of electrodes, and the electron donating layer has the general formula ( It is characterized by including the compound represented by 1).

  (Wherein R1 to R18 each independently represent hydrogen, halogen, an alkyl group, an alkoxy group, an alkenyl group, an aryl group, an aralkyl group, or a heterocyclic group. R1 and R2, and R3 and R4 each represent It may be bonded to form a ring.)

  In the general formula (1), when R1 and R2 and R3 and R4 form a condensed benzene ring, the compound is preferably represented by the general formula (2).

  (Wherein R5 to R26 each independently represents hydrogen, halogen, an alkyl group, an alkoxy group, an alkenyl group, an aryl group, an aralkyl group, or a heterocyclic group.)

  As the alkyl group, alkoxy group, and alkenyl group in the general formulas (1) and (2), those having 1 to 5 carbon atoms are preferable. Examples of the alkyl group include a methyl group, an ethyl group, and an isopropyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, and an isopropoxy group. Examples of the alkenyl group include a vinyl group and a cyclohexenyl group. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the aralkyl group include a benzyl group and a 1-naphthylmethyl group. Examples of the heterocyclic group include a furyl group, a thienyl group, and an indolyl group.

  The alkyl group, alkoxy group, alkenyl group, aryl group, aralkyl group, and heterocyclic group may have a substituent. Specific examples of the substituent include the above alkyl groups; alkylthio groups such as methoxy group, ethoxy group and n-hexylthio group; aryloxy groups such as phenoxy group and 1-naphthyloxy group; arylthio groups such as phenylthio group; chlorine A halogen atom such as bromine; a disubstituted amino group such as a dimethylamino group or a diphenylamino group; an aryl group as described above; a heterocyclic group as described above; a carboxyl group; a carboxyalkyl group such as a carboxymethyl group; Sulfonylalkyl groups; acidic groups such as phosphoric acid groups and hydroxamic acid groups; electron-withdrawing groups such as cyano groups, nitro groups, and trifluoromethyl groups.

  In the general formula (1) or (2), R6, R10, R13, and R17 are preferably a phenyl group or a naphthyl group that may be substituted. Specific examples of such compounds include compounds represented by the following formulas (3), (4), and (5).

  In the general formula (2), R5, R11, R12, and R18 are preferably a phenyl group or a naphthyl group that may be substituted. Specific examples of such a compound include a compound represented by the following formula (6).

  In the present invention, the electron donating layer may have a laminated structure composed of a plurality of layers. In this case, it is preferable that at least one of the plurality of layers contains the compound. Further, it is more preferable that the compound is contained in a layer closest to the electron-accepting layer among the plurality of layers.

  The electron-accepting layer in the present invention is not particularly limited as long as it can be used as an electron-accepting layer in an organic photoelectric conversion element. For example, materials such as fullerene, naphthalene, carbon nanotube, and perylene are used. Can do.

  In the present invention, an exciton blocking layer is preferably provided between the electron accepting layer and the electrode. The exciton blocking layer functions to confine excitons generated by light in excitation near the charge separation interface and prevent deactivation of the excitons at the electron accepting layer / electrode interface.

  The exciton blocking layer in the present invention is not particularly limited as long as it can be used as an exciton blocking layer. For example, PTCBI (3,4,9,10-perylenetetracarboxylic bis-benzo Imidazole), PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride), PTCDI (3,4,9,10-perylenetetracarboxylic diimide) and NTCDA (1,4,5,8-naphthalene) Materials such as tetracarboxylic dianhydride) and derivatives thereof can be used.

  The electrode in the present invention is not particularly limited as long as it can be used as an electrode of an organic photoelectric conversion element. For example, Al, Au, Ag, Sb, Sn, In, and a mixture of Mg and Ag Alternatively, a metal oxide or the like can be used.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the organic photoelectric conversion element which has a high open circuit voltage.

The schematic sectional drawing which shows the organic photoelectric conversion element of one Embodiment according to this invention.

  Hereinafter, the present invention will be described with reference to specific embodiments, but the present invention is not limited to the following embodiments.

  FIG. 1 is a schematic cross-sectional view showing an organic photoelectric conversion device of one embodiment according to the present invention. A first electrode 2 is provided on the substrate 1. An electron donating layer 3 is provided on the first electrode 2. An electron accepting layer 4 is provided on the electron donating layer 3. An exciton blocking layer 5 is provided on the electron accepting layer 4. On the exciton block layer 5, a second electrode 6 is provided.

  When light is incident from the substrate 1 side, the substrate 1 is preferably a light-transmitting substrate such as a glass substrate, and the first electrode 2 is preferably formed from a transparent conductive film such as indium tin oxide (ITO). The second electrode 6 can be formed from a metal or the like.

  When light is incident from the second electrode 6 side, the second electrode 6 is preferably formed of a transparent conductive film or the like.

  In the present invention, the electron donor layer 3 contains the compound represented by the general formula (1) or (2). By containing such a compound, the open circuit voltage of the organic photoelectric conversion element can be increased.

  Further, as described above, the electron donating layer 3 may have a laminated structure including a plurality of layers. In this case, it is preferable that the compound is contained in at least one of the plurality of layers constituting the stacked structure. Further, it is more preferably contained in a layer closest to the electron accepting layer 4.

  The layer constituting the electron donating layer 3 may be formed only from the compound of the present invention, or may be formed from a mixture with another compound. Other materials to be mixed with the compound of the present invention include electron donating materials. The content of the compound of the present invention in the layer in the case of using the compound of the present invention by mixing with other compounds is preferably in the range of 10 to 90% by mass, more preferably 40 to 60% by mass. It is a range.

  As materials for forming the electron accepting layer 4 and the exciton blocking layer 5, the above-described materials can be used.

  In the embodiment of the present invention, since the electron donor layer 3 contains the compound of the present invention, a high open circuit voltage can be obtained.

  Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited to the following examples.

Example 1
An organic photoelectric conversion device having the structure shown in FIG. 1 was produced. A glass substrate was used as the substrate 1, and an ITO film was formed on the glass substrate as the first electrode 2.

Next, an organic material film was deposited on the ITO film as the first electrode 2 as follows. The vapor deposition conditions were room temperature, a pressure of 10 ⁻⁵ Pa, and a deposition rate of 0.05 to 1.0 nm / second.

  The electron donating layer 3 includes 9,9 ′, 10,10′-tetraphenyl-2,2′-bianthracene [9,9 ′, 10,10′-tetraphenyl-2, having the structure of the above formula (3). 2'-biathracene] (hereinafter referred to as ED-SA1), and a film thickness of 20 nm was formed. The electron-accepting layer 4 was formed using fullerene (C60) so as to have a film thickness of 50 nm. The exciton blocking layer 5 was formed using BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) so as to have a film thickness of 10 nm.

The second electrode 6 was formed by depositing Al (aluminum) using a shadow mask of 0.03 cm ² . The thickness of each layer can be controlled by using, for example, a crystal oscillator film thickness monitor.

  The ED-SA1 represented by the above formula (3) was washed after stirring 2-chloro-9,10-diphenylanthracene in an organic solvent at 60 ° C. for 24 hours with a metal complex as a catalyst, and extracting with toluene. -It can be manufactured by performing purification.

(Examples 2 to 4)
As the electron donor layer 3, an electron donor layer having a structure in which two layers were laminated was formed. On the substrate 1 side, a layer made of DBP (dibenzotetraphenylperifuranthene) was formed to a film thickness of 10 nm, and DBP and ED-SA1 were mixed on the layer so that the mass ratio was 50:50. Formed from mixture. In Example 2, the thickness of the mixed layer was 2.5 nm, in Example 3, 5 nm, and in Example 4, 10 nm.

  Therefore, in this example, the mixed layer containing ED-SA1 is the layer closest to the electron accepting layer 4.

  Except the above, it carried out similarly to Example 1, and produced the organic photoelectric conversion element of Examples 2-4.

(Comparative Example 1)
As the electron donating layer 3, a layer having a thickness of 10 nm made only of DBP was formed. An organic photoelectric conversion device of Comparative Example 1 was produced in the same manner as Example 1 except for the above.

(Comparative Example 2)
An organic photoelectric conversion element was produced in the same manner as in Example 1 except that copper phthalocyanine (CuPc) was used as the electron donor layer 3 and a 20 nm thick layer was formed.

(Comparative Example 3)
As the electron donating layer 3, an organic material was used in the same manner as in Example 1 except that 9,10-diphenylanthracene having the structure of the following formula (7) was used and a layer formed to a thickness of 20 nm was used. A photoelectric conversion element was produced.

  DBP has the structure of the following formula (8) and is disclosed in Patent Document 1.

  BCP has the following structure.

  CuPc has the following structure.

[Measurement of open circuit voltage of organic photoelectric conversion element]
The open-circuit voltage was measured by irradiating the artificial photoelectric conversion element produced as described below with simulated sunlight generated from a solar simulator (air mass 1.5G spectrum, irradiation intensity 100 mW / cm ² ) as a light source. The measurement results are shown in Table 1.

  As is clear from the results shown in Table 1, in Examples 1 to 4 in which the compound ED-SA1 according to the present invention was used in the electron donating layer, compared with Comparative Examples 1 to 3 in which conventional electron donating materials were used, It can be seen that the open circuit voltage is significantly increased.

(Examples 5 to 8)
As an electron donating material according to the present invention, 9,9 ′, 10,10′-tetra (naphthalen-2-yl) -2,2′-bianthracene represented by the formula (4) [9,9 ′, 10] , 10'-tetra (naphthalen-2-yl) -2,2'-biathracene] (hereinafter referred to as ED-SA2) to form an organic donor element.

  ED-SA2 can be produced by the same method as ED-SA1 except for the materials used.

  In Example 5, an electron donating layer having a thickness of 20 nm was formed using only ED-SA2, and an organic photoelectric conversion device was produced in the same manner as in Example 1 except that.

  In Examples 6-8, it replaced with ED-SA1 and produced organic photoelectric conversion elements like Example 2-4 except using ED-SA2.

  With respect to the organic photoelectric conversion element produced as described above, the open-circuit voltage was measured in the same manner as described above, and the measurement results are shown in Table 2.

  As shown in Table 2, in Examples 5 to 8 using the electron donating material according to the present invention, an open circuit voltage higher than Comparative Examples 1 to 3 shown in Table 1 was obtained.

(Examples 9 to 12)
As an electron donating material according to the present invention, 5,5 ′, 12,12′-tetraphenyl-2,2′-bitetracene represented by the formula (5) [5,5 ′, 12,12′-tetraphenyl-2] , 2'-bitetracene] (hereinafter referred to as ED-SA3), an electron donating layer was formed to produce an organic photoelectric conversion element.

  ED-SA3 can be manufactured by the same method as ED-SA1 except for the material used.

  In Example 9, an electron donating layer having a thickness of 20 nm was formed using only ED-SA3, and an organic photoelectric conversion device was produced in the same manner as in Example 1 except that.

  In Examples 10-12, it replaced with ED-SA1, and produced organic photoelectric conversion element like Example 2-4 except using ED-SA3.

  With respect to the organic photoelectric conversion element produced as described above, the open-circuit voltage was measured in the same manner as described above, and the measurement results are shown in Table 3.

  As shown in Table 3, in Examples 9 to 12 using the electron donating material according to the present invention, an open circuit voltage higher than those of Comparative Examples 1 to 3 shown in Table 1 was obtained.

(Examples 13 to 16)
As the electron donating material according to the present invention, 5,5 ′, 6,6 ′, 11,11 ′, 12,12′-octaphenyl-2,2′-bitetracene represented by the formula (6) [5,5] ′, 6,6 ′, 11,11 ′, 12,12′-octaphenyl-2,2′-bitetracene] (hereinafter referred to as ED-SA4), an organic photoelectric conversion is formed. An element was produced.

  ED-SA4 can be manufactured by the same method as ED-SA1 except for the material used.

  In Example 13, an electron donating layer having a film thickness of 20 nm was formed using only ED-SA4, and an organic photoelectric conversion device was produced in the same manner as in Example 1 except that.

  In Examples 14 to 16, organic photoelectric conversion elements were produced in the same manner as in Examples 2 to 4 except that ED-SA4 was used instead of ED-SA1.

  With respect to the organic photoelectric conversion element produced as described above, the open-circuit voltage was measured in the same manner as described above, and the measurement results are shown in Table 4.

  As shown in Table 4, in Examples 13 to 16 using the electron donating material according to the present invention, an open circuit voltage higher than Comparative Examples 1 to 8 shown in Table 1 was obtained.

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... 1st electrode 3 ... Electron donation layer 4 ... Electron acceptance layer 5 ... Exciton block layer 6 ... 2nd electrode

Claims (6)

An organic photoelectric conversion element comprising a pair of electrodes and an electron donating layer and an electron accepting layer disposed between the pair of electrodes, wherein the electron donating layer contains a compound represented by the general formula (1) The organic photoelectric conversion element characterized by the above-mentioned.

(Wherein R1 to R18 each independently represent hydrogen, halogen, an alkyl group, an alkoxy group, an alkenyl group, an aryl group, an aralkyl group, or a heterocyclic group. R1 and R2, and R3 and R4 each represent It may be bonded to form a ring.) 2. The general formula (1), wherein R1 and R2 and R3 and R4 form a condensed benzene ring, and the compound is represented by the general formula (2). Organic photoelectric conversion element.

(Wherein R5 to R26 each independently represents hydrogen, halogen, an alkyl group, an alkoxy group, an alkenyl group, an aryl group, an aralkyl group, or a heterocyclic group.)   In the said General formula (1) or (2), R6, R10, R13, and R17 are the phenyl groups or naphthyl groups which may be substituted, The organic photoelectric conversion element characterized by the above-mentioned.   In the said General formula (2), R5, R11, R12, and R18 are the phenyl groups or naphthyl groups which may be substituted, The organic photoelectric conversion element of Claim 3 characterized by the above-mentioned.   5. The electron donating layer according to claim 1, wherein the electron donating layer has a laminated structure including a plurality of layers, and the compound is contained in at least one of the plurality of layers. The organic photoelectric conversion element of Claim 1.   The organic photoelectric conversion element according to claim 5, wherein the compound is contained in a layer closest to the electron-accepting layer among the plurality of layers.

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