(609f) Vertically Aligned Silicon Radial p-n Junction Micropillar Array Solar Cells | AIChE

(609f) Vertically Aligned Silicon Radial p-n Junction Micropillar Array Solar Cells

Authors 

Miller, K. J. - Presenter, University of Louisville
Walsh, K. M. - Presenter, University of Lousiville


Solar cell applications using silicon have been extensively studied in the past.  The theoretical limit of the efficiency of single-crystalline silicon solar cells is well known.  Several methods for optimizing silicon solar cells and obtaining the maximum possible efficiency exist in the literature.  Among these methods are changes in the geometry and configuration of the solar cells, such as introducing radial p-n junction solar cells.

Micro- and nanoscale radial p-n junction solar cells, in theory, result in increased solar cell efficiency compared to planar p-n junctions by reducing carrier collection length.  The geometry of arrays of these radial p-n junctions also introduces internal reflection and light trapping effects, ultimately improving the photon absorption characteristics.

We have fabricated a first-pass vertically-aligned micropillar p-n junction solar cell array with a micropillar diameter of 2 µm, length of approximately 10 µm, and distance of 2 µm between adjacent pillars.  These arrays were fabricated using conventional photolithography and deep reactive ion etching on a (100) n-type silicon wafer, followed by boron diffusion using a spin-on dopant.  Initial measurements demonstrated an open-circuit voltage of 0.36 V, short-circuit current density of 24 mA/cm2, a fill factor of 0.6, and efficiency of 5.3%.

Nanopillar p-n junction solar cell arrays of varying pillar diameters and lengths, fabricated using the combination of electron beam lithography and deep reactive ion etching, will be discussed.  The test results will be compared to planar silicon solar cells and to theoretical calculations.  With various techniques, we expect to increase the efficiencies of our solar cells beyond 10%.

Topics