EDGE PASSIVATION FOR SMAILL-AREA, HIGH EFFICIENCY SOLAR CELLS

Small-area, laboratory solar cells usually suffer significant efficiency loss after being detached from their host wafer due to edge recombination at the cut-face. This problem has afflicted the n-type Interdigitated Backside Buried Contact (IBBC) solar cells developed at UNSW, limiting the fill factor to 0.77 and the efficiency to 19.2%. In this work, the edge recombination is reduced by introducing a laser-scribed groove into the IBBC fabrication sequence to function as both edge passivation and isolation along the cell perimeter. Unlike the current laser edge isolation used in the back-end of commercial production lines, the laser-scribed isolation trench is applied in the front-end of the process and therefore receives a laser-damage etch as well as a high-quality thermal oxide. With the incorporation of this novel edge design, the dark saturation current associated with the unpassivated edge (J02) is significantly reduced from 8-11 nA/cm 2 to 3.3 nA/cm 2 , thereby increasing the fill factor to 0.79 and the