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Absolute calibrated hyperspectral photoluminescence (PL) imaging is utilized to access, in a simple and fast way, the spatial distribution of relevant solar cell parameters such as quasi‐Fermi level splitting, optical diode factor, Urbach energies Eu, and shunt resistances Rsh, without the need for electrical measurements. Since these metrics play a significant role in evaluating the process windows for electrical series interconnection by laser patterning, this approach is followed to systematically locate and quantify electrical losses that may occur as a result of the laser‐patterning process for monolithic series interconnection. It is shown that both picosecond and nanosecond laser pulses can be used for successful series interconnection. In both cases, only minor lateral material alterations occur, localized in a few μm wide region adjacent to the edges of the scribe lines. Furthermore, the acquisition and analysis of these hyperspectral PL datasets provide insights in the material removal process, from which it is concluded that the perovskite is rather resilient against the thermal impact of the laser. [ABSTRACT FROM AUTHOR]

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, but is often affected by undesired effects such as back contact delamination, flaking, and poor electrical isolation. Herein, the influence of the laser pulse duration on the electrical and compositional properties of P3 scribe lines is investigated. The results show that both nanosecond and picosecond laser pulses are suitable for P3 patterning, with the nanosecond pulses leading to a higher open circuit voltage, a higher fill factor, and a higher power conversion efficiency. It is found that the longer pulse duration resultes in a larger amount of PbI2 formed within the P3 line and a thin Br‐rich interfacial layer which both effectively passivate defects at the scribe line edges and block charge carrier in its vicinity. Thus, nanosecond laser pulses are preferable for P3 patterning as they promote the formation of beneficial chemical phases, resulting in an improved photovoltaic performance. [ABSTRACT FROM AUTHOR]

• P2 ns laser scribing of MHP SC's leads to high series resistances due to residues. • Calculations show thermal damage to the underlying layer by ns laser pulses. • Shorter ps pulses allow a more selective layer ablation with less thermal impact. • An improved morphology and electrical functionality is achieved by ps pulses. • Different ablation mechanisms are identified for ns laser and ps laser pulses. Laser-based fabrication of metal-halide perovskite mini-modules has recently been demonstrated using nanosecond (ns) laser pulses. However, it still suffers from high-resistance contacts due to remaining PbI 2 residues at the bottom of the absorber-opening P2 scribe line. Therefore, in this study, we investigate the effect of shorter picosecond (ps) laser pulses, and thus lower heat input, on the complete removal of perovskite during P2 laser patterning to achieve low series resistances and thus improved electrical performances. Based on a systematic variation of the incident laser fluence and a comprehensive electrical, morphological and compositional analysis of the scribed area, optimal process windows for successful laser-based series interconnection are identified and evidenced by current density-voltage curves. The amount of PbI 2 debris at the scribe bottom is reduced by using ps instead of ns pulses, resulting in improved j-V performance due to higher fill factor and lower series resistance. A numerical analysis of the laser-induced depth-dependent temperature profile shows that overcritical heating for both pulse durations induces explosive boiling of the excited volume, but only in the case of ns structuring the melting point of the underlying transparent oxide contact layer is exceeded. The corresponding scribed line morphology shows features of thermally-driven direct ablation (i.e., splashes), whereas ps pulses produce scribe lines with steep walls and delaminated areas, indicating a mechanical stress-assisted lift-off ablation. Accordingly, P2 laser patterning with ps pulses is recommended due to favorable morphological (steep edges) as well as composition-related (less PbI 2 residues) scribe line properties. [ABSTRACT FROM AUTHOR]