1. Field of the Invention
The present invention relates to a method of manufacturing a back-surface electrode type solar cell, and more particularly, to a method of manufacturing a back-surface electrode type solar cell in which a back-surface electrode is manufactured on a crystalline silicon substrate by using an ink jet printing method.
2. Description of the Related Art
As a green energy source able to replace depletable chemical energy resources and help reduce global warming, solar energy, along with a fuel cell, has attracted a great deal of attention.
A solar cell is an apparatus that converts light energy into electrical energy by utilizing the characteristics of a semiconductor.
Such a solar cell has a pn junction structure acquired by bonding a p-type semiconductor and an n-type semiconductor. When sunlight having energy that is higher than a gap of the energy bands of the semiconductor is incident on the solar cell having such a configuration, holes and electrons are generated within the semiconductor by the energy of the incident solar light. At this moment, in accordance with an electric field generated in the pn junction, holes (+) move to the p-type semiconductor side, and electrons (−) move to the n-type semiconductor side, whereby an electric potential is generated so as to generate a photoelectromotive force. At this time, when a load is connected between electrodes located at both ends of the pn junction, electric current flows, whereby power is generated.
Crystalline silicon solar cells that are manufactured by using a single crystalline silicon wafer and a polycrystalline silicon wafer are widely used as commercial solar cells. These crystalline silicon solar cells are manufactured by performing a process of forming a metal electrode by texturing surface processing, pn junction formation, reflection preventing film formation, and a screen printing method.
FIG. 1 is a schematic perspective view of a general back-surface electrode type solar cell according to conventional technology.
The back-surface electrode type solar cell has a front surface 12 of a crystalline silicon wafer 10 for which a texturing surface process has been performed and has a back surface electrode 40 on a back surface 14.
The back-surface electrode type solar cell having such a structure can decrease the loss occurring due to the shadow of the front surface, compared to a solar cell having electrodes formed on both sides thereof. In addition, since a back-surface junction and electrodes are separately manufactured, there is an advantage in that an additional process is unnecessary.
In addition, light absorption is increased by forming an uneven surface and performing reflection preventing film processing, and a recombination loss decreases by performing low-density doping for the front surface and a passivation process for the front and back surfaces, whereby the efficiency of the cell can be improved.
In order to develop the solar cell having such a structure, a new diffusion process technology for forming a junction on the back surface and technology for forming a back-surface electrode are needed. Since all the electrodes are positioned on the back surface, assembly of modules can be performed in an efficient manner. In addition, damage to the cell can be minimized by developing module design technology, a mass production process, and the like, whereby costs can be reduced.
For acquiring the above-described advantages, the development of a manufacturing process that is simplified and can reduce manufacturing costs is required.