TWI382548B - A two-dimensional polymer grating of the solar cells - Google Patents

Description

Solar cell with two-dimensional polymer grating

The present invention relates to a solar cell, and more particularly to a solar cell having a two-dimensional polymer grating.

At present, there are many research methods for improving the efficiency of solar cells at home and abroad, which can be roughly divided into two methods of changing solar cell component materials and collecting solar cells. Changing the solar cell component materials uses different energy gap materials to absorb photons of different wavelengths, reducing the energy release in the carrier energy band, and greatly improving the efficiency of solar cells, such as germanium and compound semiconductor solar cells and amorphous germanium solar energy. battery. The concentrating solar cell system increases the intensity of solar radiation to the solar cell, thereby improving the efficiency of the solar cell. As shown in Fig. 1, it is a schematic diagram of a conventionally diffused protective cloth type emitter cell on the back side. The cell has at least one inverted pyramid structure 11 on top, which is anisotropically etched to expose a slower crystalline surface. This inverted pyramid structure 11 can reduce the reflection of incident light on the top surface. Because the incident light perpendicular to the battery strikes the inclined face at an oblique angle and is then refracted into the interior of the battery at an oblique angle. The back contact 12 is separated from the crucible by an intermediate oxide layer. Another example is a solar cell having a concentrating property, which uses a mirror and a lens to focus sunlight, thereby increasing the power of the solar cell. However, the disadvantage of changing the material of the component is that the personnel engaged in this research must have an in-depth understanding of the physical properties of the semiconductor component in order to achieve its maximum efficacy. This method of collecting solar cells must be combined with the solar tracking system to truly improve its efficiency. Therefore, it takes more cost to be on this tracking system.

In view of the above-mentioned problems of the prior art, it is an object of the present invention to provide a solar cell having a two-dimensional polymer grating to solve various problems associated with the prior art.

According to the object of the present invention, a solar cell with a two-dimensional polymer grating is provided, which comprises a solar cell body and a two-dimensional polymer grating, and the two-dimensional polymer grating is superposed on the solar cell body. The two-dimensional polymer grating is a reflective diffraction grating with a grating depth of 180-220 μm and a grating period of 0.4-0.6 μm. The two-dimensional polymer grating has a grating pattern of two different directions, and it may be formed of a photoresist material or an organic (OG) polymer material.

According to another object of the present invention, a solar cell with a two-dimensional polymer grating is provided, characterized in that: the solar cell has a two-dimensional polymer grating, thereby improving the light receiving time of the solar cell, thereby improving the power conversion efficiency. The two-dimensional polymer grating system can be a reflective diffraction grating with a grating depth of 180-220 μm and a grating period of 0.4-0.6 μm. A two-dimensional polymer grating refers to a grating having grating patterns in two different directions, and is formed using a photoresist material or an organic (OG) polymer material. Furthermore, the two-dimensional polymer grating can be manufactured by means of overmolding, or by superimposed yellow lithography by holographic interference.

Therefore, the two-dimensional polymer grating of the present invention cooperates with the micro-electromechanical process technology and the optical interference technology, and includes soft printing technology, micro-contact printing, capillary micro-forming and replica forming technology, etc. The workers are well known, so they are not described here. Integrating these processes The method is to produce a two-dimensional polymer reflective diffraction grating. The two-dimensional reflective diffraction grating is used to reflect the light reflected by the solar substrate, so that the light is once again utilized, thereby increasing the etendue of the solar cell substrate, thereby increasing the power conversion efficiency of the solar cell.

A grating is an optical component consisting of a plurality of equally spaced periodic fine stripes; the simplest grating is a plurality of parallel equidistant dense linear grooves engraved on a flat glass or metal foil, typically on the order of tens of thousands; In principle, the grating is a multi-slit diffraction that produces the principle of diffraction as it passes through multiple slits.

Please refer to FIG. 2 , which is a schematic diagram of an embodiment of a solar cell with a two-dimensional polymer grating of the present invention. In the figure, a solar cell having a two-dimensional polymer grating includes a solar cell body 21 and a two-dimensional polymer grating 22. The two-dimensional polymer grating 22 is superposed on the solar cell body 21. The two-dimensional polymer grating 22 used in the present invention is a reflective diffraction grating having a grating depth of 180 to 220 μm and a grating period of 0.4 to 0.6 μm. The two-dimensional polymer grating 22 has a grating stripe pattern of two different directions (as shown in FIG. 2), and it may be formed of a photoresist material or an organic (OG) polymer material. Due to the physical characteristics of the grating, the light collecting efficiency on the solar cell body 21 can be increased. The two-dimensional polymer grating 22 can be manufactured by means of overmolding, or by holographic interferometric yellow lithography.

Please refer to FIG. 3, which is a flow chart of the grating fabrication of the solar cell with the two-dimensional polymer grating of the present invention. This figure describes the flow of using a mold to fabricate a two-dimensional polymer grating. In the figure, step S31 is a spin coating Polymer material polydimethylsiloxane (PDMS) and lift-off PDMS: This step is based on PDMS as a bridge for the transfer process, and then the substrate coated with PDMS is placed in the oven (Oven) to accelerate PDMS. The material is cured. Next, the Lift-Off PDMS film can be lifted. Due to the characteristics of the PDMS material, the PDMS can be easily separated from the substrate. After separation, the pattern of the grating stripe is transferred to the PDMS film. Step S32 is to inject the OG polymer material: in this step, the PDMS film to which the diffraction grating has been transferred is placed on the glass substrate, and spacers of appropriate height are placed on both sides, and a glass substrate is placed on the spacers. At this time, the PDMS film was sandwiched between two sheets of glass, and then poured into the OG polymer. Step S33 is curing the OG polymer material: in this step, the OG polymer material is cured by irradiation with a ultraviolet (UV) light source. Step S34 is to lift off the OG polymer grating: this step separates the PDMS film from the OG polymer, thus obtaining a two-dimensional OG polymer grating.

Please refer to FIG. 4, which is a flow chart of another grating fabrication of a solar cell with a two-dimensional polymer grating of the present invention. This figure depicts the process of holographic interferometry and superposition of yellow lithography to create a two-dimensional polymer grating. In the figure, step S41 is to clean the substrate: the substrate is made of glass, and the organic solvent such as acetone and methanol is combined with the ultrasonic washing machine for each shock washing, and then the impurities on the substrate are removed by shaking with deionized water, and then the substrate is placed. In the oven, the moisture on the substrate is removed at a high temperature. Step S42 is a spin coating photoresist and a soft baking photoresist: a photoresist having a room temperature is uniformly applied to the substrate by a spin coater, and then the photoresist is soft baked. Step S43 is to make a diffraction grating pattern by using holographic interference lithography: placing the soft-baked substrate on the plane of the two laser light intersections, and reflecting at this time The grating pattern is photosensitive above the substrate with photoresist. Step S44 is exposure, baking and development: heating is performed. In order to reduce the chopping phenomenon caused by the photoresist in the photosensitive light and accelerate the dissociation of the photoresist molecules. The reflective diffraction grating substrate is further developed with a developing solution, followed by fixing with deionized water, and then the substrate is blown dry with nitrogen, and finally baked in an oven.

As shown in FIG. 2 to FIG. 4, the solar substrate with the two-dimensional reflective diffraction grating has higher power conversion efficiency than the original solar substrate, and the invention has the advantages of simple process and low manufacturing cost.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

11‧‧‧Inverted pyramid structure

12‧‧‧Back contact

21‧‧‧ solar cells

22‧‧‧Two-dimensional polymer grating

23‧‧‧Light

S31 to S34‧‧‧ Step procedure

S41 to S44‧‧‧ Step procedure

1 is a schematic view of a conventional solar cell of a two-dimensional polymer grating of the present invention; FIG. 2 is a schematic view of an embodiment of a solar cell with a two-dimensional polymer grating of the present invention; A flow chart for fabricating a solar cell with a two-dimensional polymer grating according to the present invention; and FIG. 4 is a flow chart for fabricating another grating of a solar cell with a two-dimensional polymer grating of the present invention.

21‧‧‧ solar cells

22‧‧‧Two-dimensional polymer grating

23‧‧‧Light

Claims (7)

A solar cell with a two-dimensional polymer grating, comprising: a solar cell body; and a reflective diffractive two-dimensional polymer grating directly superposed on the solar cell body, the reflective diffraction is two-dimensionally high The molecular grating reflects the light reflected by the solar cell body back to the solar cell body by the reflection characteristic to enhance the light receiving time of the solar cell body, thereby improving the power conversion efficiency. The solar cell with a two-dimensional polymer grating according to claim 1, wherein the two-dimensional polymer grating has a grating depth of 180 to 220 μm. The solar cell with a two-dimensional polymer grating according to claim 1, wherein the two-dimensional polymer grating has a grating period of 0.4 to 0.6 μm. The solar cell with a two-dimensional polymer grating according to claim 1, wherein the two-dimensional polymer grating has a grating stripe pattern in two different directions. The solar cell with a two-dimensional polymer grating according to claim 1, wherein the two-dimensional polymer grating is formed of a photoresist material or an organic (OG) polymer material. The solar cell with a two-dimensional polymer grating according to claim 1, wherein the two-dimensional polymer grating can be manufactured by overmolding. The solar cell with a two-dimensional polymer grating according to the first aspect of the patent application, wherein the two-dimensional polymer grating can be holographically involved in the yellow light micro Shadow technology is manufactured.