Dresden, Germany -- At this week's LASYS 2012 in Stuttgart, researchers from the Fraunhofer IWS and Technische Universität Dresden are showing a method for fast, efficient nanostructuring of organic solar cells.
Laser processing is used to improve various aspects of solar cell and panel performance, from texturing the material's surface, high-speed drilling of holes for emitter wrap-throughs, edge deletion and glass drilling, and scribing narrow lines.
Now, scientists at Fraunhofer IWS and the Institute for Applied Photo Physics (IAAP) of the Technische Universität Dresden describe what they say is an improvement with using lasers to structure solar cells, which shortens processing times and increases resolutions. Their "direct laser beam interference patterning" (DLIP) method utilizes collimated and coherent laser beams to superimpose onto a substrate surface; an interference structure occurs through the entire superposition volume of the beams. A single laser pulse can process up to several sq. cm of surface area, leading to effective structuring speed of several sq. cm per second.
Specifically they looked at organic solar cells on PET foils, and determined that the cells' efficiency could be increased by up to 10% on such structured substrates. A brief description from Fraunhofer IWS explains the process:
The superposition of two laser beams results in a linear structure. This procedure achieves an efficiency increase of approximately 10 % compared to the non-structured PET substrate. Three beams that are not within the same spatial plane form a point structure. The structuring period is defined by the angle between two laser beams and their wavelengths. Crossed structures are made in a two-step process. First a linear structure is imprinted and then the substrate is rotated by 90° prior to repeating the same structuring step. This technology turns out to be especially advantageous for organic cells on PET foils and leads to an efficiency increase of 21 %.
A compact laser interference system to enable an inline structuring process developed for industrial implementation, and its process principle, can be seen at this week's LASYS 2012 in booth 4.C31.
DLIP system (animation), via Fraunhofer IWS.