Optimization and benchmarking of the Mercury IBC cell

In this work the the Mercury solar cell was optimized. The Mercury cell is an IBC front oating emitter (FFE) cell and was compared with an IBC front surface eld (FSF) cell to see the bene ts. And the emitter contact was improved to increase the e ciency of the Mercury cell. The FSF IBC cells are the most e cient single junction solar cells[1], that nowadays are available. An IBC cell has the contacts at the rear, leaving the front totally free to receive sunlight. Although this design yield high e ciencies, they are very expensive. The Mercury cell is an IBC cell design to reduce the cost of the IBC cell at the cost of minimal e ciency loss and be producible by industry. This still high e ciency, easy manufacturing design should lower the production cost of solar energy, and thereby compete with fossil fuels as energy source. The Mercury cell design was determined via simulation, using the program Quokka. This program was also used to see the di erence between the FFE and the FSF cell. In this work a method was developed to give a picture of the performance of the cell as function of changing parameters. Hereby a function was tted over multiple simulated points to see the behavior of the solar cell. In this work, mostly the parameter change in dimensions were examined. Two designs for the Mercury cell, producible by industry, were optimized in this work. The high e ciency (HE) cell, with small features but high e ciency, up to 21.1%. And the easy manufacturing (EM) design, with larger features with an e ciency of 20.6%. The optimization of the EM design result in an emitter half width is 415 μm and BSF half width is 175 μm, for the optimization of the EM design result in both emitter and BSF half widths of 500 μm. To see the value of the Mercury design, the FFE was compared with an FSF, which are both IBC cells, only with a di erent front. The two Mercury designs, the HE and the EM cell, were used in this comparison. For the HE design, with small features, the e ciency was the same for the FFE as for the FSF cell. For the EM design the advantage of the Mercury cell is shown, because the FFE cell is 2% absolute more e cient than the FSF cell. An EM FFE cell is less e ective than a HE FFE cell, but the losses are relatively low, much less than for the FSF cells. Furthermore, one of the biggest losses in a cell is the recombination at the emitter contact. Therefore a deep boron emitter was tested to see whether this improves the cell. The deep boron di usion shields the contacts better from electrons, and thereby reduce the recombination. Experimentally the deep boron emitter was studied. Cells with the deep boron emitter were made and compared with cells with a regular emitter, and subsequently it was compared with simulated work to underpin the results. With the deep boron emitter contact the open circuit voltage of a cell, was higher than with a regular boron di usion. Where screen printed contacts contacting a regular boron di usion has a saturation current density of 3000 fA/cm this deep boron di usion gives a saturation current density of only 1000 fA/cm, these values are determined by simulations. The deep boron emitter e ciently shields the emitter from electrons to reduce recombination, and thereby increase the voltage yield from a solar cell. Quokka simulations show that the HE FFE cell with a deep boron emitter will have an increase of e ciency of 0.2 % absolute and the EM FFE cell of 0.1 % absolute.