Injection-dependent lateral resistance in front-junction solar cells with nc-Si:H and a-Si:H hole selective contact

We investigate the role of lateral transport of minority carriers in the wafer for front-junction solar cells. The study is based on two silicon heterojunction solar cells with p-type amorphous (a-Si), and nanocrystalline (nc-Si) silicon as hole selective layer respectively. The solar cells feature similar certified efficiencies (23.23% and 23.45%). Unexpectedly, FF and RS at MPP of both solar cells are also similar. Fitting the JV curves in high-forward bias, and analytical calculations suggest that lateral transport is also taking place in the wafer at high injection, despite the front–junction configuration. This is supported by numerical device simulations. Both reveal that junction-related RS is lower with nc-Si(p) than with a-Si(p). The results underline the importance of analyzing JV curves over a wide voltage range unravel different phenomena determining FF.