Impact of Boron Doping Concentration on Tunnel Oxide Passivated Contact in Front Surface for N-Type Poly-Si Based Passivated Contact Bifacial Solar Cells

This article reports on a novel bifacial tunneling oxide passivated contact n-PERT bifacial c-Si solar cell structure. This cell uses bifacial tunneling oxide passivated contact structures on the front and rear surfaces. The analysis focuses on the impact of the boron doping concentration on the passivation performance of the tunneling oxide passivated contact structures on the front surface. The simulations were performed with boron doping concentration > 1E20 cm
⁻³
, Silicon dioxide layer thickness > 0.9 nm, and Silicon dioxide layer quality (interface-states density
D
_it
= 1 × 10
¹⁰
cm
⁻²
/eV and pinhole density
D
_ph
< 1 × 10
⁻⁴
) for Silicon dioxide layer at boron doping concentration of 1E20 cm
⁻³
. Implied open circuit voltage (
iV
_oc
) and recombination current density (
J
_oe
) reaches up to 729 mV and 8.62 fA/cm
²
(
D_n
= 5 × 10
¹⁵
cm
³
). The open-circuit voltage of the prepared bifacial tunnel oxide passivated contact solar cell with a large area of 252 cm
²
reaches up to 704.5 mV. The average conversion efficiency is 22.08%, which is 0.15% higher than that of the solar cell with traditional PERT structure on the front side and tunneled oxide passivated contact on the rear side. The main factors limiting the efficiency improvement of this structured cell are the parasitic absorption of light by the front surface polysilicon and the minority carrier lifetime of the silicon wafer. By simulating and optimizing, the highest conversion efficiency of the cell can reach 24.38% and the open-circuit voltage of the cell can reach 727.4 mV.