Non-vacuum coating method for preparing light absorbing layer of solar cell
A coating method for preparing a light absorbing layer of a solar cell is provided. In a non-vacuum environment, an ultrasonic vibrating mixer is employed to mix a CIGS mixture with a mixing fluid to obtain a CIGS coating material. The CIGS coating material is then uniformly coated on a molybdenum (Mo) layer which is driven by a conveyor device, so as to form a CIGS coating material layer having a uniform thickness on the Mo layer. An infrared ray (IR) heating lamp is then used to dry the CIGS coating material layer for removing residue of the mixing fluid remained in the CIGS coating material layer. In such a way, a CIGS light absorbing layer adapted for absorbing a solar energy and converting the absorbed solar energy into an electric energy is obtained. The CIGS light absorbing layer can be then used for fabricating a CIGS solar cell.
1. A non-vacuum coating method for forming a copper/indium/gallium/selenium (CIGS) layer on a molybdenum layer deposited on a glass substrate in a non-vacuum environment under an atmospheric pressure, wherein the glass substrate together with the Mo layer deposited thereon is driven to move by a conveyor device, the non-vacuum coating method comprising:
utilizing an ultrasonic vibrating mixer to mix a CIGS mixture with a mixing fluid to obtain a uniform CIGS coating material;
distributing the CIGS coating material via a delivering pipeline to a plurality of ultrasonic nozzles, wherein the ultrasonic nozzles are positioned over the Mo layer;
applying an ultrasonic vibration for spraying the CIGS coating material onto the Mo layer, and forming a CIGS coating material layer; and
utilizing a plurality of infrared ray (IR) heating lamps for generating an IR radiation to conduct a drying process to the formed CIGS layer for removing residue of the mixing fluid remained in the CIGS coating material layer, thus obtaining the CIGS layer, wherein the CIGS layer is adapted for serving as a light absorbing layer of a solar cell.
2. The non-vacuum coating method according to claim 1 , wherein the CIGS mixture comprises Cu(InGa)Se 2 powders or Cu(InGa)Se 2 particles.
3. The non-vacuum coating method according to claim 1 , wherein the mixing fluid is selected from a group consisting of pure water, deionized water, alcohol, and acetone.
4. The non-vacuum coating method according to claim 1 , further comprising a spraying control unit for controlling an amount of the CIGS coating material sprayed by each of the ultrasonic nozzles.
5. The non-vacuum coating method according to claim 1 , wherein the ultrasonic nozzles are spacedly arranged in alignment with the Mo layer on the glass substrate.
6. The non-vacuum coating method according to claim 1 , wherein the IR heating lamps are spacedly arranged in alignment with the CIGS coating material layer.
7. The non-vacuum coating method according to claim 1 , wherein the CIGS coating material layer has a thickness within the range of 1.5 to 5 μm.
8. The non-vacuum coating method according to claim 1 , wherein the drying process comprises a heating process and a cooling process, wherein a heating rate of the heating process is within the range of 2 to 10° C./minute, a cooling rate of the cooling process is within the range of 2 to 10° C./minute, and a maximum heating temperature of the drying process is within the range of 30 to 250° C.