Contact-Induced Recombination Analysis for Photovoltaics (CIRAP) using one-time Suns-Voc

초록

The contact-formation process is a critical determinant of the final performance of high-efficiency silicon solar cells. Among existing characterization methods, the Suns-VOC measurement is widely employed to evaluate the intrinsic performance of fully processed solar cells under open-circuit conditions, in which the influence of series resistance is eliminated. This technique enables the extraction of key recombination-loss components, including the emitter (J0e), base (J0b), and space-charge region (SCR)(J0SCR or J02), providing insight into the internal recombination mechanisms of the device. In passivated emitter and rear cells, J0fc can be extracted by adjusting the metal-emitter contact fraction. However, this approach cannot be applied to silicon heterojunction (SHJ) cells in which full-area contact exists between the transparent conducting oxide (TCO) and doped amorphous silicon. In this study, we define a contact-induced recombination-loss parameter, J0c, to characterize the recombination loss in SHJ structures. We propose contact-induced recombination analysis for photovoltaics (CIRAP), a method for extracting J0c from Suns-VOC measurements performed on fully processed SHJ solar cells. This method extracts J0c from Suns-VOC data using nonlinear curve fitting, providing a complementary diagnostic capability that reduces the dependence on additional test structures. Using CIRAP, we extract J0c values in the range of 10-8 to 10-9 A/cm2, reflecting the recombination loss induced by the TCO contact. This work provides a nondestructive and accurate diagnostic tool for process optimization in high-efficiency silicon solar cells.

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