[10p-N104-1~18] 16.3 Bulk, thin-film and other silicon-based solar cells

[10p-N104-1] Improved temperature coefficients in very thin c-Si solar cells

〇Hitoshi Sai¹, Yoshiki Sato¹, Toshiki Oku¹, Takuya Matsui¹ (1.AIST)

Keywords:solar cell, silicon, temperature coefficient

In general, the conversion efficiency of solar cells decreases with the increase in temperature. This temperature dependence is mitigated by enhancing V_OC. Given a solar cell, its V_OC can be enhanced by several routes, e.g., reducing the defect density within the absorber, applying passivating contacts, and reducing the absorber thickness. In this work, we investigate the impact of wafer thickness in c-Si cells from the viewpoint of the photovoltaic performance at elevated temperatures. It is confirmed experimentally that the V_OC of c-Si solar cells increases by thinning the Si wafer, e.g., V_OC >0.75 V is obtained at a wafer thickness of < 60 um with a conversion efficiency of 22.7%. It is also confirmed that thin c-Si cells exhibiting high V_OC show less temperature dependence. As a result, the optimum wafer thickness for maximizing the efficiency decreases with the increase in temperature according to the relation of -1.1 um/°C. Numerical simulation predicts that this tendency becomes more emphasized with the suppression of Shockley-Read-Hall recombination. These findings suggest that the device structure of c-Si cells including the wafer thickness should be optimized depending on the operating temperature in the field.