Enhanced photovoltaic properties for rear passivated crystalline silicon solar cells by fabricating boron doped local back surface field

Abstract

In order to enhance the p-type doping concentration in the LBSF, boron was added into the aluminum paste and boron doped local back surface field (B-LBSF) was successfully fabricated in this work. Through boron doping in the LBSF, much higher doping concentration was observed for the B-LBSF over the Al-LBSF. Higher doping concentration in the LBSF is expected to lead to better rear passivation and lower rear contact resistance. Based on one thousand pieces of solar cells for each type, it was found that the rear passivated crystalline silicon solar cells with B-LBSF showed statistical improvement in their photovoltaic properties over those with Al-LBSF.

Keywords

crystalline silicon solar cells / rear passivation / local back surface field / doping concentration

References

[1] Mandelkorn J, Lamneck JH Jr.. Simplified Fabrication of Back Surface Electric Field Silicon Cells and Novel Characteristics of Such Cells[C]. Proc. 9th IEEE Photovoltaic Spec. Conf., 1972 66-71.

[2] Fossum JG. Physical Operation of Back-surface-field Silicon Solar Cells[J]. IEEE Tran. Electron Dev., 1977, ED-24(4): 322-325.

[3] Blakers AW, Wang A, Milne AM, et al. 22.8% Efficient Silicon Solar Cell[J]. App. Phys. Lett., 1989, 55(13): 1 363-1 365.

[4] Das A, Kim DS, Nakayashiki K, et al. Boron Diffusion with Boric acid for High Efficiency Silicon Solar Cells[J]. J. Electrochem. Soc., 2010, 157(6): H684-H687.

[5] Wang A, Zhao J, Green MA. 24% Efficient Silicon Solar Cells[J]. App. Phys. Lett., 1990, 57(6): 602-604.

[6] Western NJ, Sung A, Wenham SR, et al. Localized Ohmic Contact Through a Passivation Dielectric for Solar Cell Rear Surface Design[J]. App. Phys. Lett., 2013, 102(22): 222105

[7] Dullweber T, Kranz C, Peibst R, et al. PERC+: Industrial PERC Solar Cells with Rear Al Grid Enabling Bifaciality and Reduced Al Paste Consumption[J]. Prog. Photovolt.: Res. App., 2016, 24(12): 1 487-1 498.

[8] Tous L, Aleman M, Russell R, et al. Evaluation of Advanced p-PERL and n-PERT Large Area Silicon Solar Cells with 20.5% Energy Conversion Efficiencies[J]. Prog. Photovolt.: Res. App., 2015, 23(5): 660-670.

[9] Hoex B, Heil SBS, Langereis E, et al. Ultralow Surface Recombination of c-Si Substrates Passivated by Plasma-assisted Atomic Layer Deposited Al₂O₃[J]. App. Phys. Lett., 2006, 89(4): 042112

[10] Hoex B, Schmidt J, Bock R, et al. Excellent Passivation of Highly Doped p-type Si Surfaces by the Negative-charge-dielectric Al₂O₃[J]. App. Phys. Lett., 2007, 91(11): 112107

[11] Zhao J, Wang A, Green MA. High-efficiency PERL and PERT Silicon Solar Cells on FZ and MCZ Substrates[J]. Sol. Energy Mat. Solar Cells, 2001, 65(1-4): 429-435.

[12] Wang Z, Han P, Lu H, et al. Advanced PERC and PERL Production Cells with 20.3% Record Efficiency for Standard Commercial p-type Silicon Wafers[J]. Prog. Photovolt.: Res. App., 2012, 20(3): 260-268.

[13] Rodofili A, Fell A, Hopman S, et al. Local p-type Back Surface Fields Via Laser Chemical Processing (LCP): First Experiments[C]. 2008 1 808-1 811.

[14] Kluska S, Granek F. High-efficiency Silicon Solar Cells with Boron Local Back Surface Fields Formed by Laser Chemical Processing[J]. IEEE Electron Dev. Lett., 2011, 32(9): 1 257-1 259.

[15] Sze SM, Ng KK. Physics of Semiconductor Devices, 2007 3 Hoboken, New Jersey: John Wiley & Sons.

[16] Lölgen P, Sinke WC, Leguijt C, et al. Boron Doping of Silicon Using Coalloying with Aluminum[J]. App. Phys. Lett., 1994, 65(22): 2 792-2 794.

[17] Duran C, Eisele SJ, Buck T, et al. Bifacial Solar Cells with Selective B-BSF by Laser Doping[C]. 2009 1 775-1 778.

[18] Hameiri Z, Mai L, Wenham SR. Laser Doped Local Back Surface Field[C]. Proc. 37th IEEE Photovoltaic Spec. Conf., 2011 1054-1 057.

[19] Palina N, Mueller T, Mohanti S, et al. Laser Assisted Boron Doping of Silicon Wafer Solar Cells Using Nanosecond and Picosecond Laser Pulses[C]. Proc. 37th IEEE Photovoltaic Spec. Conf., 2011 2 193-2 197.

[20] Gu X, Yu X, Xu J, et al. Towards Thinner and Low Bowing Silicon Solar Cells: Form the Boron and Aluminum Co-doped Back Surface Field with Thinner Metallization Film[J]. Prog. Photovolt.: Res. App., 2013, 21(4): 456-461.

[21] Du G, Chen B, Chen N, et al. Efficient Boron Doping in the Back Surface Field of Crystalline Silicon Solar Cells Via Alloyed-aluminumboron Paste[J]. IEEE Electron Device Lett., 2012, 33(4): 573-575.

[22] Rauer M, Schmiga C, Raugewitz A, et al. Theoretical and Experimental Investigation of Aluminum-boron Codoping of Silicon[J]. Prog. Photovolt.: Res. App., 2016, 24(2): 219-228.

[23] Du G, Zhang Y, Li W, et al. Performance Enhancement of Multicrystalline Silicon Solar Cells and Modules Using Double-layered SiNx: H Antireflection Coatings[J]. Prog. Photovolt.: Res. App., 2015, 23(12): 1 806-1 814.

[24] Urrejola E, Peter K, Plagwitz H, et al. Al-Si Alloy Formation in Narrow p-type Si Contact Areas for Rear Passivated Solar Cells[J]. J. App. Phys., 2010, 107(12): 124516