JPH043672B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric conversion element with improved light absorption efficiency.

The photoelectric conversion elements used in conventional organic solar cells are
As shown in FIG. 1, it has a structure in which a translucent aluminum metal electrode 2, an organic dye thin film 3, and an opaque silver metal electrode 4 are stacked in this order on a glass substrate 1. Such a photoelectric conversion element is manufactured without paying special consideration to the surface shapes of the metal electrodes 2 and 4, so the translucent aluminum metal electrode 2 on the incident light side is also an opaque silver metal electrode. 4
Both have smooth, flat surfaces.

Therefore, among the dipoles of the dye molecules of the organic dye thin film 3 that absorbed light, components parallel to the metal electrodes 2 and 4 create a mirror image relationship induced in the smooth plane metal. The electric field of the dipole is
Since it works in the direction of canceling the dipole of the organic dye thin film 3, the organic dye thin film 3 near the metal electrodes 2 and 4 apparently reduces light absorption, and only a part of the incident light energy can be used. There were flaws.

This invention was made in view of the above points, and includes a translucent metal electrode in contact with one side of an organic dye thin film used in a photoelectric conversion element such as a merocyanine dye thin film, and a metal electrode in contact with the other side.
By making the surface of at least one metal electrode in contact with the organic dye thin film a finely uneven surface,
It is an object of the present invention to provide a photoelectric conversion element with increased absorption intensity of light energy and improved photoelectric conversion efficiency. The present invention will be explained below based on the drawings.

FIG. 2 is a sectional view showing a schematic structure of a photoelectric conversion element which is an embodiment of the present invention.

A first layer of translucent metal electrode 12 is formed on a glass substrate 11 by vapor deposition. During this vapor deposition, the metal evaporation source and the glass substrate 11 are placed in a perpendicular positional relationship, and the evaporated metal vapor is perpendicularly incident on the glass substrate 11 to form a semi-transparent metal electrode 12 with a smooth plane. Next, metal vapor is deposited by arranging the glass substrate 11 obliquely to the evaporation source so that the incident angle to the glass substrate 11 on which the metal electrode 12 is evaporated is 50 degrees to 80 degrees. The evaporation rate and the temperature of the glass substrate 11 are determined so that the metal evaporated thin film has an island-like structure. In this way, the second layer of metal electrode 13 having projections and depressions is formed. The thickness of the translucent thin film of the metal electrode 12 is from 80 angstroms to 120 angstroms in the case of aluminum, and the thickness of the semitransparent thin film of the metal electrode 13 is also from 50 angstroms to 90 angstroms in the case of aluminum.
Angstrom is suitable. As a result, the surface of the semi-transparent metal electrode 12 becomes a finely uneven surface.

Next, an organic dye thin film 14 is deposited. In this case, the glass substrate 11 on which the metal electrodes 12 and 13 are formed is placed so as to be perpendicular to the evaporation source. The optimal thickness of the organic dye thin film 14 is 300 to 600 angstroms. Furthermore, since the organic dye thin film 14 is sufficiently thin, the surface of the film is uneven due to the influence of the unevenness of the surface of the underlying metal electrode 13. Therefore, if the opposing metal electrode 15 is also vertically deposited, the interface with the organic dye thin film 14 will be uneven.

Next, the operation of the photoelectric conversion element shown in the above embodiment will be explained. The dye molecules of the organic dye thin film 14 that have absorbed light can be regarded as dipoles. When the dye molecules are near the metal electrodes 13 and 15, they induce mirror-image dipoles in the metal. Among the dipoles of the dye molecules, the components parallel to the surfaces of the metal electrodes 13 and 15 create dipoles that are induced in the opposite direction in the metal, canceling the dipoles of the dye molecules and reducing the apparent absorption of light. It turns out. However, since the metal electrode structure of the above embodiment has unevenness on the surface, the size of the dipole induced in the metal electrodes 13 and 15 is limited, and the induced dipole is smaller than that of a smooth plane electrode. . As a result, the dipoles of the dye molecules in the organic dye thin film 14 are less likely to be canceled out, and the apparent light absorption can be increased.

FIG. 3 is a diagram showing the wavelength dependence of the absorption coefficient of a merocyanine dye thin film on an aluminum metal electrode. In the figure, curve A shows the case of the photoelectric conversion element having the structure of the above embodiment shown in FIG. 2, and curve B shows the case of the conventional photoelectric conversion element shown in FIG. As is clear from the figure, in the case of the above embodiment in which the metal electrode has a structure in which a smooth plane aluminum metal thin film is covered with a translucent aluminum metal thin film by an oblique vapor deposition method, the conventional smooth plane aluminum metal The light absorption coefficient is increased compared to the case of thin film metal electrodes.

In addition, in the above embodiment, the semitransparent metal electrode 1
Although both the metal electrode 15 and the metal electrode 15 have uneven surfaces, the light absorption coefficient increases even if either one of them has uneven surfaces. Further, the structure of the uneven surface may be formed by attaching fine metal particles by evaporation as described above, or by making the surface itself uneven.

As explained in detail above, the present invention provides a photoelectric conversion element comprising a translucent metal electrode, an organic dye thin film, and a metal electrode, in which the surface of at least one of the metal electrodes on the side in contact with the organic dye thin film is made into an uneven surface. Therefore, there is an advantage that the light absorption intensity in the organic dye thin film can be increased and the photoelectric conversion efficiency can be improved.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a schematic structure of a conventional photoelectric conversion element, Fig. 2 is a diagram showing a schematic structure of a photoelectric conversion element constituting an embodiment of the present invention, and Fig. 3 is a diagram showing a schematic structure of a photoelectric conversion element according to an embodiment of the present invention. FIG. 3 is a diagram showing the wavelength dependence of the light absorption coefficient of a thin film. In the figure, 11 is a glass substrate, 12, 13, and 15 are metal electrodes, and 14 is an organic dye thin film.

Claims (1)

[Claims] 1. In a photoelectric conversion element in which an organic dye thin film is formed on a semitransparent metal electrode, and a metal electrode is formed on this organic dye thin film, the surface of at least one of the metal electrodes on the side that is in contact with the organic dye thin film is A photoelectric conversion element characterized by having a finely uneven surface.