| Summary: | 碩士 === 國立成功大學 === 電機工程學系 === 102 === Since the use of green-energy has been one of the global trends, the demand for solar cell increases rapidly. Thus, more details about manufacturing solar cells should be developed. In this study, mechanism of constructing ohmic contact between front electrode and Si-based solar cell will be investigated. Newly-invented paste and process are used in the preparation of front electrode.
In this study, paste was printed with narrow line screen printing process on polycrystalline Si solar cell which has already finished the back Al printing and deposition of double anti-reflection coatings (DARCs). Then, two-step firing process was applied to sinter the front electrode and obtain the ohmic contact between front electrode and solar cell. The two-step firing process was accomplished in air atmosphere and reducing atmosphere. The first step was in air atmosphere. In this process, PbO-based glass frit etched the DARCs and Ag recrystallized at the surface of Si, constructing the preliminary contact. The second step was in reducing atmosphere. In this process, CuO reduced to Cu and sintered. Besides, Ag nanoparticles recrystallized in the glass layer at interface due to the interactions between H2, Ag and PbO-based glass frit and the volatility of Pb, constructing the ohmic contact between electrode and solar cell. Scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and four-point probe were employed to analyze the results after each process.
By experiment and analysis, reaction mechanism in each stage was surmised, and it was also proven that ohmic contact and good sheet resistance for front electrode could both be obtained by applying newly-invented paste and process. The lowest sheet resistance of front electrode measured was 0.090 Ω/□.
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