Buried Contact Group
High-Efficiency P-Type Commercial Silicon Solar Cell
The Double-sided Buried Contact (DSBC) solar cell incorporates a high-efficiency rear surface design in the commercially successful Laser-groove or Buried-contact cell design (shown below). The rear grid provides localised contacts to the base and allows the majority of the rear surface to be passivated, for example either by a dielectric coating or in conjunction with a doped layer. If successful, this structure will allow increased open-circuit voltage in thin-wafer solar cells. Another advantage of a rear grid contact is that it allows a light trapping scheme to be implemented independent of the electrical requirements of the rear contact allowing high short-circuit current to be maintained.
Schematic of the DSBC solar cell.
DSBC solar cells typically exhibit good open-circuit voltage and light-generated current, but suffer from reduced fill factor. Detailed modelling of the local ideality factor curve as a function of voltage (m-V) and current voltage curves (I-V, or J-V if current density) have demonstrated a possible link between these low fill factors and assymetric Shockley-Read-Hall (SRH) recombination in the bulk region, the cause of which is currently under investigation[1].
Other research efforts include identifying the mechanism lowering the fill factor of the DSBC solar cell and identifying the stress mechanisms that occur during the growth of silicon on textured wafers(see 2003 Annual Report Section 5.3.1).
[1] P.J. Cousins, C.B. Honsberg, A.B. Sproul and J.E. Cotter, “The effect of SRH recombination on the fill factor of double sided buried contact solar cells”, 40th ANZSES Conference, Newcastle, 2002.