Solar photovoltaic electricity: Current status and future prospects

Lasers provide the ability to accurately deliver large amounts of energy into confined regions of a material in order to achieve a desired response. For opaque materials, this energy is absorbed near the surface, modifying surface chemistry, crystal structure, and/or multiscale morphology without altering the bulk. This chapter covers a brief introduction to the fundamental principles governing laser propagation and absorption as well as the resulting material responses. We then highlight two case studies of improving efficiency in photovoltaic and optoelectronic devices as well as optimizing cell-surface interactions in biological interfaces.

Fundamentals of Laser-Material Interaction and Application to Multiscale Surface Modification

A novel ultrafast laser processing technique is used to create self-assembled micro/nano structures on a silicon surface for efficient light trapping. Under appropriate experimental conditions, light reflection (including scattering) of the Si surface has been reduced to less than 3% for the entire solar spectrum and the material appears completely black to the naked eye. A post-chemical cleaning is applied to remove laser-redeposited material and induced defects. Optical, morphological, and structural characterizations have been carried out on as-laser-treated and post-chemically cleaned surfaces. Finally, we report for the first time the total efficiency of over 14% and high external quantum efficiency (EQE) results on photovoltaic devices fabricated on the ultrafast-laser-induced micro/nano structured silicon wafer, which can be further improved upon process optimization. Copyright © 2011 John Wiley & Sons, Ltd.

Efficient light trapping in silicon solar cells by ultrafast-laser-induced self-assembled micro/nano structures

A process using laser-ablated pits to texture the front surface of monocrystalline and multicrystalline silicon solar cells is described. Optical and electrical characterization demonstrates that the technique performs as well as upright random pyramid texturing and causes no laser-induced defects or laser shunting. Double-sided buried contact solar cells fabricated with laser texture performed as well as those fabricated with upright random pyramid textures on 1 Ω cm, p type float-zoned wafers. Copyright © 2006 John Wiley & Sons, Ltd.

Optical and electrical properties of laser texturing for high-efficiency solar cells

Optical properties of silicon light trapping structures for photovoltaics

In the evolution of single‐crystal silicon solar cells, crystallographic texturing of the cell surface using anisotropic etches was an important step in improving cell performance. Unfortunately, this technique is ineffective for polycrystalline silicon solar cells due to generally unfavorable grain orientation. This limitation has been overcome by employing a new laser texturing technique on the top surface of a laser grooved, buried top contact polycrystalline silicon solar cell. This approach has demonstrated an independently confirmed 16.7% (air mass 1.5, 25 °C) efficiency for a 10.5 cm2 polycrystalline silicon solar cell, the highest efficiency ever reported for a polycrystalline cell of this size.

John C. Zolper

Papers

16. 7% efficient, laser textured, buried contact polycrystalline silicon solar cell