Towards High Throughput Texturing of Polymer Foils for Enhanced Light Trapping in Flexible Perovskite Solar Cells using Roll‐to‐roll Hot Embossing

Abstract

A path to further increase the power conversion efficiency of perovskite solar cells is maximizing sunlight absorption by using patterned substrates with enhanced light trapping capabilities. However, to be competitive with traditional solar cells, especially in niche markets, low cost texturing methods need to be developed. In this work, we present as a proof‐of‐concept a roll‐to‐roll hot embossing method to pattern flexible PET foils. The cylindrical mold for the embossing process was structured with periodic grooves by picosecond Direct Laser Interference Patterning (DLIP). The optical characterization of the textured PET shows a tenfold increase in the haze factor (diffuse to global transmittance ratio) compared to flat PET due to the high intensity diffracted beams. Flexible triple cation perovskite cells deposited onto these patterned substrates show on average an 8 % (relative) higher efficiency than similar devices deposited on a reference flat PET substrate. This enhancement can be attributed to the increase in the light trapping provided by the textured substrate. Finally, a cost analysis model shows that the additional cost of integrating the proposed hot embossing step into a perovskite solar module manufacturing facility would represent less than 0.35 % of the initial fabrication cost.