Transparent flat body

Translucent flat body

Technical field

The invention relates to a transparent flat body with two transparent outer layers sandwiching a in an electric field its light transmittance changing active layer between two optionally divided into sections electrode layers, and a preferably connected to the electrode layers via a control stage photovoltaic element comprising a having photoactive layer between two electrode layers.

State of the art

Translucent flat body, such as those formed by liquid crystal displays or in their light transmittance controllable windows, exhibit in an electric field its light transmittance changing active layer between two optionally divided into sections electrode layers, on what is necessary to control the active layer electric field is at least partially applied. When using liquid crystals forming substantially parallel to the layer liquid crystal molecules nematic rotational cells, rotate the liquid crystal molecules when an electric field in the field direction and return to the twisted structure after switching off the electrical voltage of the field-oriented state. Through the use of polarizing filters on both outer layers of the active layer, the field-oriented state by Lichtab- sorption be visualized. Electrochromic active layers on the other hand is based on the interaction of two colorless or pale-colored, one hand oxidizable and secondly reducible substances, one of which is reduced under the influence of an electrical voltage and the other is oxidized, at least one of these substances is colored. After switching off the voltage, the two original redox substances are formed again, under a discoloration or color clarification. for building up the electric field to control the light transmittance of the active layer, since comparatively small electrical values ​​are required regardless of the structure of the active layer, photovoltaic elements lend themselves to the energy supply, especially due to the photosensitivity of photovoltaic elements a simple self-control the light transmittance of the active layer can be realized , A disadvantage of the therefor for use next photovoltaic elements that they must have a sufficiently large receiving surface for a light radiation, to ensure the necessary energy supply. The therefor required space increases with decreasing efficiency. This applies in particular for photovoltaic elements whose photoactive layer is not established in a conventional manner on silicon, but rather on conjugated polymers, in which alternately successive single and double bonds. Here arise with regard to the electron energy with semiconductors comparable energy bands so that they can be converted by doping the non-conducting to metallic conduction. To improve the efficiency of energy conversion of photovoltaic polymer cells of a conjugated polymer is to build known (US 5670791 A), the photoactive layer of two molecular components, namely a conjugated polymer component as electron donor and a fullerene as an electron acceptor. By this measure, the usual charge carrier recombination could be largely avoided, which indeed leads to a significant increase in efficiency which, however, in comparison to silicon-based photovoltaic elements still low. Summary of the Invention

The invention is thus based on the object to provide a light transmissive flat body of the type described above a photovoltaic element with the energy required for controlling the active layer, and indeed provide a comparatively low construction costs, without additional space for the arrangement of the photovoltaic element to have to.

The invention solves this problem in that the photoactive layer of the photovoltaic element is in a known manner from two transparent molecular components that one of the two electrode layers of the active layer is one of the electrode layers of the photovoltaic element at the same time and that the two transparent layers, both the include photovoltaic element and the active layer therebetween.

Since a photovoltaic element having a photoactive layer of two transparent molecular components is used as electron donor and electron acceptor used, the light transmissive flat body itself may serve as a support for the photovoltaic element so that the photovoltaic element can extend over the entire surface of the light transmissive flat body. So that sufficient for the control of the active layer of the light transmissive flat body electrical energy can be provided also at a comparatively low efficiency of energy conversion. In spite of the comparatively large-area photovoltaic element of the construction cost remains low because one of the two electrode layers of the active layer of the light transmissive flat body is utilized as an electrode for the photovoltaic element whose photoactive layer is thus built up on one electrode layer of the light-permeable flat body. This means that not only transparent layers between the active layer of the light-transmitting plate body and the photoactive layer of the photovoltaic element exceeded are liquid, but also the considerable effort of producing a separate electrode layer for the photovoltaic element on the side of the active layer of the light-transmitting plate body can be omitted. Both the active layer of the light-transmitting plate body as well as the photoactive layer of the photovoltaic element are sandwiched between two common, transparent covering layers, which in turn allows a common sealing of the light transmissive flat body and the photovoltaic element.

In general, since the power supply of controllable in terms of its light transmittance flat body should be ensured irrespective of the light transmittance in each case selected, it is recommended that the photovoltaic element on the light source side facing the active layer to be arranged.

Brief Description of Drawing

In the drawing, the subject invention is illustrated, for example, namely, an inventive light-transmissive flat body is shown in a schematic cross section.

BEST MODE FOR CARRYING OUT THE INVENTION

The transparent flat body has, according to the illustrated embodiment, two transparent outer layers 1, 2 of glass or plastic, sandwiching one hand an active layer 3 for controlling the light transmittance and on the other hand, a photoactive layer 4 of a photovoltaic element. 5 The active layer 3 may be constructed in the usual manner as electrochromic layer applied between two electrode layers 6 and 7 an electric field can be exposed on the light transmittance of the active layer 3 is controlled. These electrode layers 6 and 7 are preferably made of indium tin oxide (ITO), but in contrast to conventional, with respect to its Light transmittance controllable flat bodies, in particular windows, only one of the two electrode layers 6, 7 is applied on a transparent cover layer first The top layer of the 1 facing away from the electrode layer 6 is in fact at the same time electrode layer for the photovoltaic element 5, the other electrode layer is associated with 8 of the top layer. 2 The photoactive layer 4 of the photovoltaic element 5, which may be a multilayer structure, consisting of a conjugated polymer as an electron donor and a fullerene as an electron acceptor. While the lochsammelnde electrode layer 6 is made of a transparent conductive oxide, the elektronensammelnde electrode layer 8 of the photovoltaic element 5 may be made of aluminum, which is deposited on the photoactive layer 4th Due to the small layer thickness and the metallic electrode layer 8 is transparent.

With the excitation of the conjugated polymer by irradiated light, electrons are delivered to the fullerene of the photoactive layer 4, resulting in a corresponding voltage build-up. Since the electrode layer 8 is electrically connected via an electrical terminal 9 having the electrical terminal 10 of the electrode layer 7, the active layer 3, due to the voltage build-up in the photoactive layer 4 due to the common electrode layer 6, an electric field between the electrode layers 6 and 7, the chemical the reaction of the redox of the active layer 3 and thus its color behavior controls. In order to influence this control, 9 and 10 a corresponding control circuit 11 can be switched in the electrical connection of two electrical terminals.

If the active layer 3 is not made up of electrochromic substances, but created on the basis of liquid crystals, so Although the mode of action of the active layer 3, but not its control over the photovoltaic element 5. The outer layers 1 and 2 have changed, however, with corresponding polarization layers 12 and 13 provided, as is indicated by dashed lines in the drawing to the alignment of the liquid crystal molecules to be able to utilize in the direction of the electric field for the shading of the light transmissive flat body.

Although shown in the drawing, the light transmissive flat body in the form of a window pane, the invention is not limited to this embodiment but may also be used in connection with a liquid crystal display. For this purpose, the electrode layer 7 is to divide accordingly, and the parts separated from one another to control, in order to obtain through the resulting control of individual liquid crystal cells arranged in a matrix pattern of liquid crystal cells of the active layer 3 a display.

By combining an active layer 3 for controlling the light transmittance with a photovoltaic element 5 for supplying power to the controller of the active layer 3 in a common light transmissive flat body simple constructional conditions are created that as well as sharing an electrode layer 6 between the active layer 3 and the photoactive layer 4 the transparent outer layers 1 and 2 allow for the two layers 3 and 4. FIG. Moreover, the two layers may be sealed together 3 and 4, because even only the marginal gap between the cover layers 1 and 2 is sealed via a seal fourteenth The mutual spacing of the outer layers 1 and 2 can be ensured by means of spacers 15, which preferably carry the electrical connections 9 and 10. FIG.