Heterojunction emitter for rear junction n-type solar cells

In this paper heterojunction emitters formed by intrinsic and doped amorphous silicon layers on top of the crystalline silicon are presented as a promising option for rear junction n-type silicon solar cells which are suited for the indoor application. In a preliminary test, n-type solar cells with a rear-junction heterojunction emitter show higher open circuit voltages compared to rear-junction cells with a screen-printed Al-alloyed emitter. 15.6% efficiency heterojunction emitter cells have been obtained without any optimization. From a characterization of the emitter saturation current density, we conclude that optimization of the amorphous silicon deposition conditions can improve the HIT emitter quality and that the implied open circuit voltage can be as high as 698 mV, which is very encouraging especially also for low light intensity applications.