The impacts of emitter and base carrier density on Si-chalcopyrite hetero-junction solar cells using AMPS-1D

Silicon based chalcopyrite (with the compounds composition I(B)-III(A)-VI(A)₂) hetero-junction solar cells have been reported with the potential of high conversion efficiency theoretically. The hetero-junction solar cell with PNN⁺ structure is fabricated as: front metal electrodes/transparent conductive oxide (TCO)/ p-type chalcopyrite layer emitter/n-type silicon base/ n⁺ silicon back surface doping/ rear metal electrodes. By the means of numerical analysis with AMPS-1D simulation, the impacts of chalcopyrite emitter carrier density and Si base doping concentration were studied. Higher chalcopyrite acceptor density N_A and TCO work function Φ help to obtain higher efficiency until N_A=7×10¹⁶/cm³. As for n-type silicon base doping, the concentration N_D should be as large as possible for more space charge and electric field in space charge region (SCR). Normally it is hard to get heavily doped n-type feedstock and wafers. Instead of entirely heavy doping silicon, a thin heavily doped layer (N_D = 1 × 10²⁰/cm³) were inserted between chalcopyrite layer and silicon base (N_D = 1 × 10¹⁶/cm³), and a similar conversion efficiency was obtained.