Large-area ∼20% efficient silicon solar cells using fine line direct printing
This paper presents the use of a finer line printing technology for achieving over 20.2% efficient cells with oxide/nitride rear passivation and screen-printed local back contacts on large-area (239 cm2) commercial grade Cz Si wafers. The front metal gridlines are printed by a one-step non-contact approach of a modified silver printable paste. The line width is as narrow as 55μm, and the line height is more than 35μm after firing in a conventional belt furnace. The significantly reduced metal converge on the front side resulted in reduced shadowing loss and an increase in absolute cell efficiency of ~0.5% compared to the screen-printed reference solar cells. Increasing the number of gridlines from 74 to 83 in conjunction with reduced line width from 100 μm to 55 μm increased the Jsc by ~0.5 mA/cm2 to 38.4 mA/cm2. This combined with a Voc of 657 mV and FF of 80.0% produced the 20.2% efficient cell compared to a 19.7% screen-printed cell.