19%-efficient and 43?mu m-thick crystalline Si solar cell from layer transfer using porous silicon

We present a both-sides-contacted thin-film crystalline silicon (c-Si) solar cell with a confirmed AM1.5 efficiency of 19.1% using the porous silicon layer transfer process. The aperture area of the cell is 3.98?cm2. This is the highest efficiency ever reported for transferred Si cells. The efficiency improvement over the prior state of the art (16.9%) is achieved by implementing recent developments for Si wafer cells such as surface passivation with aluminum oxide and laser ablation for contacting. The cell has a short-circuit current density of 37.8?mA?cm-2, an open-circuit voltage of 650?mV, and a fill factor of 77.6%. Copyright (c) 2011 John Wiley & Sons, Ltd.