Evaluation of electrical shunt resistance in laser scribed thin-films for CIGS solar cells on flexible substrates

Formation of serial interconnects in thin-film solar cells is an important step for upscaling production yield over large areas. Laser scribing is a promising tool for monolithic interconnect formation in CIGS solar cell module. However, evaluation of alterations in electrical properties of the cells during the laser scribing is not a trivial task, especially for cells with flexible substrates when production is based on roll-to-roll processes. We applied the technique of nested circular scribes proposed by K. Zimmer et. al. for the in-line quality evaluation of the P3 scribing processes in CIGS solar cells on polyimide. Scribing experiments were performed using picosecond laser working at 532 nm wavelength. Parallel resistance values of the cells during the formation of P3 scribes were extracted by analyzing I-V characteristics of the measured photovoltaic devices. Integration of laser scribing experiments with the on-line electrical characterization facilitated optimization of the laser processes and increased the measurement accuracy of shunt formation during the laser scribing.