Rear passivation of commercial multi-crystalline PERC solar cell by PECVD Al_2O_3

摘要

Low-cost high-efficiency solar cells are the key to achieve grid parity with photovoltaic devices. Multi-crystalline silicon (mc-Si) solar cells are low-cost but low-efficiency. High-quality rear passivation is essential for the achievement of this goal. This dielectric stack, in conjunction with a local back surface field, produced mc-Si passivated emitter and rear cell (PERC) which efficiency exceeded 18.6%. The peak efficiency of 18.63% was achieved with J_(sc) of 37.44 mA/cm~2 and V_(oc) of 638 mV on commercial grade mc-Si wafers. Detailed characterization and modeling revealed that the increase in V_(oc) and J_(sc) is the result of increased back surface reflectance from 74.8% to 90.7% and reduced back surface recombination velocity from 1800 to 260 cm/s. It was observed that the efficiency of mc-Si PERC solar cells decreased in degradation experiment.