A Novel Rear Emitter N-Type PERT Silicon Cell Structure with Stable High Performance

摘要

In a novel rear emitter n-PERT (passivated emitter, rear totally-diffused) cell design, the boron diffused emitters are placed at the rear surface of the n-type silicon substrates. This has significant improved cell efficiency up to 22.7%, which was confirm at Sandia National Laboratories. A 170 μm thin FZ substrate and a 1.5 Ω-cm modest substrate resistivity have helped these cells to achieve highly efficient carrier collection to the rear emitter. Hence, these cells demonstrated up to 40.1 mA/cm~2 high short-circuit current density and high cell efficiency. Some of these cells have also demonstrated high Voc of 706 mV, which is as high as the best Voc from the p-type PERL cells. This clearly demonstrates the high efficiency potential of these rear emitter n-PERT cells. These 22 cm~2 large rear emitter cells were scribed off from the silicon wafer, representing efficiencies for applicable devices. Another advantage of these rear emitter cells is that they have demonstrated very stable performances both under one-sun illumination, and after a few months storage in nitrogen.