Optimization of laser patterning process for eco-friendly tin-halide perovskite solar module – with a nanosecond green laser

The tin-based perovskite solar cells are promising future eco-friendly photovoltaic technology with increasing efficiency, which relies on fluorine-doped tin oxide (FTO) or indium tin oxide (ITO) as a transparent conducting oxide (TCO) for front contact. In the monolithic module fabrication process interconnections are executed by a series of three scribes with two different lasers 1064 nm and 532 nm. This study aims to simplify the interconnection process in tin-based perovskite solar modules by using a single visible laser source to perform all three scribes. The study uses an inverted device structure of Glass/TCO/ Poly(3,4-ethylenedioxythiophene): Polystyrene sulfonate (PEDOT: PSS)/Formamidinium-tin-iodide (FASnI₃)/C60/Bathocuproine (BCP)/Ag and a 532 nm nanosecond pulsed laser source to pattern the ITO and FTO (P1 scribe), the PEDOT: PSS/FASnI₃/C60/BCP stack (P2 scribe), and the PEDOT: PSS/FASnI₃/C60/BCP/Ag (P3 scribe). The quality of the P1 scribe is assessed by examining the edges, completeness of film removal, cracking, film delamination, and elemental mapping using a stylus profiler, optical microscope, and energy dispersive x-ray spectroscopy. The P1 scribe is completely removed with line widths of 70 µm and 110 µm of ITO and FTO, respectively, without damage to the glass substrate. The profiles are steep, and the electrical isolation is greater than 40 MΩ. The same 532 nm laser is used for P2 and P3 scribes. The ablation of PEDOT: PSS during P2 and P3 scribe is studied by Raman spectroscopy. The results show that the use of a single 532 nm laser source can simplify the patterning process of monolithic tin-based perovskite solar modules, and potentially reduce production costs.