METAL MICRO-GRID ELECTRODE FOR HIGHLY EFFICIENT SI MICROWIRE SOLAR CELLS WITH OVER 80 FILL FACTOR

摘要

Applicants demonstrate novel micro-grid top electrode for highly efficient radial junction Si microwire solar cells. The micro-grid electrode allows the shallow (sheet resistance of -100 Ω/sq) junction emitter to function properly without optical and electrical losses and thus power conversion efficiency of Si microwire solar cell can be enhanced by collecting photocarriers effectively from the shallow emitter through the electrode without serious Auger/surface recombination. By optimizing the micro-grid structure, our microwire solar cells with areas of 1 cm2 show a conversion efficiency of up to 16.5 %, with an open-circuit voltage of 565.2 mV and a short-circuit current density of 35.9 mA/cm². In particular, over 80 % fill factor (max 81.2 %) is obtained reproducibly due to significant decreases in metal and contact resistances when Applicants applied an electroplating method to form thick Ni electrode of about 1 μπι thickness. The use of the novel micro-grid to build an ideal metal/emitter interface therefore presents a unique opportunity to develop highly efficient microwire solar cells.