Review of Laser Doping and its Applications in Silicon Solar Cells

Abstract

Laser-doped selective emitter diffusion techniques have become mainstream in solar cell manufacture covering 60% of the market share in 2022 and are expected to continue to grow to above 90% within the next five years (ITRPV). This was a very rapid uptake of technology, coming from only ∼10% penetration in 2018, and has enabled over 20 fA/cm 2 front recombination current reductions on the dominant passivated emitter and rear cell concepts in the same short period. In this article, a broad overview of key concepts in relation to laser doping methods relevant to solar cell manufacturing is given. We first discuss the basic mechanisms behind laser doping along with the benefits over conventional doping methods. The main laser doping approaches reported in the literature are then discussed, along with implications for metallization strategy, particularly in relation to selective emitter and back surface field formation in the dominant passivated emitter and rear cell technology. Different cell concepts that have benefited from the application of laser doping are also discussed. In the last section, we discuss the main defects induced by laser processing of silicon which affect the finished devices, potential and debated causes, as well as some commonly applied treatments for their mitigation.

Performance of Large Area n-TOPCon Solar Cells with Selective Poly-Si Based Passivating Contacts Prepared by PECVD Method

“…The solubility of doped elements in liquid Si is an order of magnitude higher than that in the solid state. By adjusting laser power, wavelength, and pulse parameters, diffusion or activation of dopants can be achieved [23]. Due to the significant recombination introduced by the frontal contact of n-TOPCon solar cells [17], B-SE technology has garnered increased attention and been extensively investigated by scholars [11].…”

Rational Approach for High‐Efficiency Dopant‐Free Solar Cells Characterized with Key Parameters

“…To create shallow junctions and reduce Auger recombination, various methods such as ion implantation, [ 11–13 ] plasma doping, [ 14,15 ] and laser doping [ 16–18 ] have been explored. However, due to the anisotropic diffusion of ionized dopants, achieving uniform p–n junctions on 3D c‐Si surfaces is challenging; this leads to a decrease in shunt resistance and a consequent decrease in efficiency.…”

“…Additionally, the thermal doping process uses dopant sources such as POCl 3 and BBr 3 , which are not environmentally friendly because of their toxic and corrosive properties. [10] To create shallow junctions and reduce Auger recombination, various methods such as ion implantation, [11][12][13] plasma doping, [14,15] and laser doping [16][17][18] have been explored. However, due to the anisotropic diffusion of ionized dopants, achieving uniform p-n junctions on 3D c-Si surfaces is challenging; this leads to a decrease in shunt resistance and a consequent decrease in efficiency.…”

Fabrication of Smart Materials Using Laser Processing: Analysis and Prospects

“…Laser processing can be used to activate or introduce functional additives into a material, enhancing its properties [38,39]. For example, laser-doped selective emitter diffusion techniques have become mainstream in solar cell manufacture [40]. This method is also a promising one-step method for creating conductive micropatterns for electronic devices and sensors [41].…”