SILICON HETEROJUNCTION SOLAR CELLS ON N- AND P-TYPE WAFERS WITH EFFICIENCIES ABOVE 20

摘要

A systematic comparison of front- and rear-emitter silicon heterojunction solar cells produced on nandp-type wafers was performed, in order to investigate their potential and limitations for high efficiencies. Cells onp-type wafers suffer from reduced minority carrier lifetime in the low-carrier-injection range, mainly due to theasymmetry in interface defect capture cross sections. This leads to slightly lower fill factors than for n-type cells.However, these losses can be minimized by using high-quality passivation layers. High V_(oc)s were obtained on bothtypes of FZ wafers: up to 735 mV on n- and 726 mV on p-type. The best V_(oc) measured on CZ p-type wafers was only692 mV, whereas it reached 732 mV on CZ n-type. The highest aperture-area certified efficiencies obtained on 4 cm~2cells were 22.14% (V_(oc)=727 mV, FF=78.4%) and 21.38% (V_(oc)=722 mV, FF=77.1%) on n- and p-type FZ wafers,respectively, demonstrating that heterojunction schemes can perform almost as well on high-quality p-type as on ntypewafers. To our knowledge, this is the highest efficiency for a full silicon heterojunction solar cell on a p-typewafer, and the highest V_(oc) on any p-type crystalline silicon device with reasonable FF.