Optimized laser patterning process to reduce ‘dead areas’ in perovskite PV

CHEOPS, a European research project with a focus on upscaling perovskite photovoltaic cells, has released a new research that shows a way to reduce the 'dead area' of photovoltaic cells by applying an enhanced laser patterning process. This new development means that more of the area of a cell can be used for energy conversion, making it more efficient.

For upscaling efforts to achieve suitable currents, photovoltaic cells are usually split into a series of interconnected segments. It is these breaks in the material that need to be made as small as possible to be able to optimize the cell for energy conversion. This so-called 'dead area' has been reduced to a width of 400μm by using a new laser patterning process.

The process requires three lines of varying depth to create trenches in the cells, allowing the current to flow between the front contact and the electrode material attached to the back of the perovskite only. To do this, CHEOPS used three different laser sources. UV, IR and green lasers with varying pulse frequencies were used to remove create the trenches. The difficulty of this process lay in removing the unwanted layers without damaging the rest. In addition to this, the trenches had to balance being small enough to reduce the dead area while also being large enough for sufficient insulation.

Despite the challenges, CHEOPS produced a solar cell of 140mm2, which achieved an efficiency of 16% while decreasing the dead area to aperture area ratio to 8%. While this a remarkable achievement, CHEOPS has vowed to improve the laser patterning process further to reduce this ratio to 3-5%.

In November 2017, the CHEOPS project shared updates on progress made at commercializing PSCs.