Development of a diffused junction silicon solar cell pilot line

In the interest of expediting future pilot line start-ups for solar cell research, the development of Arizona State University's student-led pilot line at the Solar Power Laboratory is discussed extensively within this work. Several experiments and characterization techniques used to formulate and optimize a series of processes for fabricating diffused-junction, screen-printed silicon solar cells are expounded upon. An experiment is conducted in which the thickness of a PECVD deposited anti-reflection coating (ARC) is varied across several samples and modeled as a function of deposition time. Using this statistical model in tandem with reflectance measurements for each sample, the ARC thickness is optimized to increase light trapping in the solar cells. A response surface model (RSM) experiment is conducted in which 3 process parameters are varied on the PECVD tool for the deposition of the ARCs on several samples. A contactless photoconductance decay (PCD) tool is used to measure the dark saturation currents of these samples. A statistical analysis is performed using JMP in which optimum deposition parameters are found. A separate experiment shows an increase in the passivation quality of the a-SiNx:H ARCs deposited on the solar cells made on the line using these optimum parameters. A RSM experiment is used to optimize the printing process for a particular silver paste in a similar fashion, the results of which are confirmed by analyzing the series resistance of subsequent cells fabricated on the line. An in-depth explanation of a more advanced analysis using JMP and PCD measurements on the passivation quality of 3 aluminum back-surface fields (BSF) is given. From this experiment, a comparison of the means is conducted in order to choose the most effective BSF paste for cells fabricated on the line. An experiment is conducted in parallel which confirms the results via Voc measurements. It is shown that in a period of 11 months, the pilot line went from producing a top cell efficiency of 11.5% to 17.6%. Many of these methods used for the development of this pilot line are equally applicable to other cell structures, and can easily be applied to other solar cell pilot lines.