Monolithic Interconnection of Thin Film Minimodule Prepared by a CNC Mechanical Scribing

Monolithic interconnection is a key strategy for thin-film photovoltaic (PV) modules, enabling dense series-connected cell arrays without external wiring. Conventional laser scribing, however, requires complex optimization and can be unsuitable for high-melting-point or highly transparent materials. This work demonstrates a low-cost, flexible alternative based on fully mechanical scribing using a computer numerical control (CNC) system. Kesterite (Cu₂ZnSnSe₄) thin-film minimodules with Mo/CZTSe/CdS/ZnO/ITO architecture were fabricated and interconnected into an 8-cell series configuration. By selecting scribing tips of different hardness, specific layers were selectively removed without damaging underlying contacts, achieving effective P1–P2-P3 patterning. The interconnected module delivered a total open-circuit voltage of 2.65 V, consistent with the sum of individual cell voltages, while maintaining comparable current and shunt resistance. Main performance losses arose from increased series resistance and reduced active area, limiting power conversion efficiency to 2% for the module, 3.1% for the module active area, versus a efficiency of 6% for an individual reference cell. These results highlight mechanical scribing as a practical method for early-stage PV technologies and a potential complement to laser scribing in industrial applications.