High Efficiency HJT Battery
HJT cell is a kind of high efficiency crystalline silicon solar cell which can be realized at low cost. The battery is based on the n-type silicon with high life. The p-n hetero junction is formed by depositing the intrinsic amorphous silicon film and p-type amorphous silicon film on the front of the cashmere cleaned silicon wafer. On the back of the wafer, the intrinsic amorphous silicon film and the n-type amorphous silicon film are deposited successively to form the back surface field. Then transparent conductive oxide films are deposited on both sides of the doped amorphous silicon films. Finally, metal electrodes are formed on both sides through screen printing technology to form a symmetrical structure of hjt solar cell. The cell structure has the advantages of less process steps, low process temperature, no lid and PID effect, low temperature coefficient, high efficiency, etc. the highest efficiency record has reached 26.33%.
The structure and process of hjt solar cells are quite different from that of conventional silicon-based solar cells. In general, hjt solar cells have the following characteristics:
(1) Structural symmetry
(2) Low temperature manufacturing process
(3) High open circuit voltage
(4) Good temperature characteristics
(5) No lid and PID effect
There are also some problems with the hjt battery, such as:
(1) The equipment investment is high, because the thin film deposition technology is adopted, the vacuum equipment with high requirements is needed;
(2) The requirements of the process are strict, and the interface of amorphous silicon / crystalline silicon with low interface state is obtained. The requirements of the process environment and operation are also high;
(3) Generally, the cost of indium oxide doped metal oxide is high, and the unit consumption of silver paste is high due to the high resistivity of silver paste at low temperature;
(4) Low temperature package technology is needed. Because of the low temperature process characteristics of the hjt battery, the traditional high temperature package technology of the crystal silicon battery can not be used. Therefore, suitable low temperature package technology needs to be developed.