Hetero-junction (HIT) silicon solar cell model for AMPS-1D simulation

Mono and polycrystalline silicon solar cell modules currently represent between 85 and 90% of the PV world market. The reasons are the stability, robustness and reliability of this kind of solar cells as compared to those of emerging technologies. Then, in the mid-term, silicon solar cells will continue playing an important role for their massive terrestrial application. One important approach is the development of silicon solar cells processed at low temperatures (less than 300degC) by depositing amorphous silicon layers with the purpose of passivating the silicon surface, and avoiding the degradation suffered by silicon when processed at temperatures above 800deg C. This kind of solar cells are known as HIT cells (Heterojunction with an intrinsic layer) and are already produced commercially (Sanyo Ltd), reaching efficiencies around 23%. In this work we shall find the conditions and parameters needed for the crystalline silicon and amorphous silicon layers that allow high conversion efficiencies. These solar cell are simulated by means of AMPS-1D, which is a program developed at Pennsylvania State University. We shall discuss the modifications required for simulating this kind of structures since this program explicitly does not take into account interfaces with high interfacial density of states as occurs at the amorphous-crystalline silicon interface. Finally, optimization of the HIT cells will also be discussed.