1. Field of the Invention
The present invention relates generally to a solar cell structure, and more particularly, to a solar cell structure having a back transparent conductive oxide (TCO) layer or an interface layer having a coarse upper surface, which is adapted for facilitating to scatter light, thus improving the light absorbing efficiency.
2. The Prior Arts
A typical thin film solar cell usually includes a substrate, a back electrode, a primary light absorbing layer and a front electrode. Conventionally, the front electrode often has a surface configured with humps, and the back electrode is often a high reflective metal back electrode, so as to achieve more light paths in the primary light absorbing layer for capturing the light transmitted therein.
Referring to
A light L incident to the solar cell 1 can be reflected by the first reflective metal layer 55 and the second reflective metal layer 65 to the semiconductor thin film layer 70. Therefore, the employment of the first reflective metal layer 55 and the second reflective metal layer 65 enhances the photoelectric conversion efficiency of the semiconductor thin film layer 70.
Referring to
A primary objective of the present invention is directed to provide a solar cell structure. The solar cell structure includes a substrate, a front transparent conductive oxide (TCO) layer, a primary light absorbing layer, a back TCO layer, and a metal thin film layer stacked from bottom to top. The back TCO layer includes a coarse upper surface.
Another objective of the present invention is directed to provide a solar cell structure. The solar cell structure includes a substrate, a front TCO layer, at least one first light absorbing layer, at least one interface layer, at least one second light absorbing layer, a back TCO layer, and a metal thin film layer stacked from bottom to top. The interface layer includes a coarse upper surface.
According to the present invention, because the back TCO layer or the interface layer has a coarse upper surface, the light is facilitated for further scattering, so that the light absorbing efficiency can be improved, thus improving the efficiency of the solar cell.
The present invention will be apparent to those skilled in the art by reading the following detailed description of a preferred embodiment thereof, with reference to the attached drawings, in which:
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
The primary light absorbing layer includes at least one light absorbing layer (not shown in the drawings). The at least one light absorbing layer for example is one of a tandem solar cell, a triple junction solar cell, or a multi junction solar cell.
The front TCO layer 15 and the back TCO layer 25 are preferably made of a ZnO-based material. The substrate 10 is preferably a glass substrate. The dry etching process for example can be a hydrogen plasma processing. The metal thin film layer 35 for example is made of silver (Ag).
It should be noted that although only one first light absorbing layer, one interface layer, and one second light absorbing layer are exemplified as shown in
The substrate 10, the front TCO layer, the first light absorbing layer 22, and the interface layer 23 are sequentially stacked one on another from bottom to top. The interface layer 23 includes a coarse upper surface 32. Preferably, the coarse upper surface 32 is formed by a dry etching process. The coarse upper surface 32 is configured with a plurality of humps (not shown in the drawings). A distance (not shown in the drawings) is defined between apexes of two adjacent humps. A bottom between the two adjacent humps and the apexes of the two adjacent humps 30a define an included angle (not shown in the drawings). Preferably, the distance is controlled to be less than 200 nm, and the included angle is controlled to be within the range of 30° to 150°. The second light absorbing layer 24, the back TCO layer 25, and the metal thin film layer 35 are then sequentially stacked on the coarse upper surface 32.
The interface layer 23 is preferably made of a ZnO-based material. The substrate 10 is preferably a glass substrate. The dry etching process for example can be a hydrogen plasma processing. The metal thin film layer 35 for example is made of silver (Ag).
The first light absorbing layer 22 and the second light absorbing layer 24 for example can be made of a material selected from the group consisting of I-III-VI compound, amorphous silicon (a-Si), amorphous silicon-germanium (a-SiGe), and microcrystalline silicon (uc-Si). The I-III-VI compound for example includes one of copper-indium-gallium-selenium (CIGS), copper-gallium-selenium (CGS), copper-gallium-selenium (CIS), and silver-indium-gallium-selenium (AIGS).
In summary, according to the present invention, a coarse upper surface is configured on the back TCO layer or the interface layer of the solar cell structure. The coarse upper surface facilitates to further scatter the incident light, so that the light absorbing efficiency of the solar cell can be improved, and so does the efficiency of the solar cell.
Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.