Nanocrystalline Silicon Oxide Stacks for Silicon Heterojunction Solar Cells for Hot Climates

Today, solar cells are generally optimized for 25 degrees C, whereas in most climates, especially hot and sunny ones, the operating device temperature is usually much higher, e.g. in the range of 60 degrees C. We investigate the use of n-doped nanocrystalline silicon oxide layers (nc-SiOx:H(n)) as front contact stacks in silicon heterojunction solar cells and compare them with oxide-free front contacts. Whereas a short-circuit current density of 41 mAcm(-2) could be obtained due to the increased transparency of the nc-SiOx:H(n) layers, the fill-factor is drastically reduced and leads to a reduced efficiency at 25 degrees C. Albeit the FF can be partly recovered at 60 degrees C, the highest efficiencies at 60 degrees C were so far obtained for the solar cells with oxide-free front contact stacks.