Preparation Of Heterojunction Cell With P Silicon Substrate And The Influence Of Hydrogen Annealing Process Of Intrinsic Amorphous Silicon Thin Film On The Performance Of HIT Cell

The Heterojunction with intrinsic thin-layer cell is the silicon battery with the structural feature, which is to add an intrinsic hydrogenated amorphous silicon thin film in PN junction. The advantages of HIT cell are high efficiency of crystalline silicon cell and simple technology of thin film cell. Sanyo announced that the efficiency of the latest battery reaches 25.6% and the area of the cell is 143.7cm2.However, the efficiency of crystalline silicon solar cells is only 20.4%. This paper mainly researches the simple heterojunction cells with substrate of P type silicon and hydrogen annealing process of intrinsic thin film of HIT cells with substrate of N type silicon. The main content is as follows:(1)At first we used the ratio frequency plasma enhanced chemical vapor deposition(RF-PECVD) technique to prepare n type μ-Si:H thin films and researched on the influence of Si H4 concentration SC, PH3 doping ratio RP, discharge power P and substrate temperature T on the crystalline fraction, deposition rate and dark conductivity of the thin films. Then we applied these parameters to heterjunction cells.Studies have shown that: ①With the increase of Si H4 concentration, the crystalline fraction and dark conductivity of thin films are gradually reductive, but the deposited rate increases. ②With the increase of PH3 doping ratio, the crystalline fraction and dark conductivity rise slowly, and the deposition rate increases firstly and then decreases. ③With the increase of discharge power, the crystalline fraction and dark conductivity gradually decreases and deposition rate increases.④With the increase of substrate temperature, the crystalline fraction and dark conductivity increase firstly and decreases lastly; the deposition rate increases gradually. On the condition of Si H4 concentration of 1.5%, PH3 doping ratio of 0.9%,discharge power of 90 W,substrate temperature of 220℃ and pressure of 1torr(133.3Pa), we prepared an n type μ-Si:H thin film of dark conductivity of 21.0S/cm. This condition is also the optimized condition of cell preparation. The open-circuit of the cell is 593 m V and the efficiency is 9.02%.(2)Then we researched the annealing treatment to the a-Si:H thin film of HIT cells with N type substrate and analyzed the influence of annealing temperature and time on the cells performance. The former team has researched the influence of annealing treatment to i-a-Si:H thin film on the minority-carrier lifetime. On this basis, we study the effect of annealing treatment to i-a-Si:H thin film on the performance of HIT cells. The experimental results indicate that: with the increase of annealing temperature, the tendency of the efficiency and open-circuit voltage is increasing firstly and then decreasing; the appropriate annealing temperature is 320℃.With the prolong of annealing time, the efficiency and open-circuit voltage will rise and then reduce rapidly. The optimized condition is annealing temperature of 320 ℃,annealing time of 80 min and deposition pressure of 1torr, the performance of cell is greatest. The open-circuit voltage is 620 m V and the efficiency is 10.14%.