Improved Electrical Performance of Perovskite Photovoltaic Mini-Modules through Controlled PbI<inf>2</inf> Formation Using Nanosecond Laser Pulses for P3 Patterning

The upscaling of perovskite solar cells to modules requires the patterning of the layer stack in individual cells that are monolithically interconnected in series. This interconnection scheme is composed of three lines, P1‐P3, which are scribed using a pulsed laser beam. The P3 scribe is intended to isolate the back contact layer of neighboring cells. Previous research has shown that the P3 patterning is often affected by undesired effects such as back contact delamination, flaking, and poor electrical isolation, as laser‐material interactions are not yet fully understood. In this study, the influence of the laser pulse duration on the electrical and compositional properties of P3 scribe lines is investigated. The results show that both ns and ps laser pulses are suitable for P3 patterning, with the ns pulse leading to higher open circuit voltage, higher fill factor, and higher power conversion efficiency. It is found that the longer pulse duration resulted in a larger amount of PbI2 formed within the P3 trench. Next to the P3 line edge, the formation of a thin Br‐rich layer at the perovskite/hole transport layer interface was observed when ns laser pulses were used, which extends up to 12 µm into the active area of the module. Both the formation of PbI2 and a more Br‐rich perovskite layer effectively passivate defects at the edges of the scribe line and block charge carriers in its vicinity. It is concluded that ns laser pulses are preferable for P3 patterning as they promote the formation of beneficial chemical phases, resulting in an improved photovoltaic performance