Laser-doped silicon solar cells by Laser Chemical Processing (LCP) exceeding 20% efficiency

Abstract

The introduction of selective emitters underneath the front contacts of solar cells can considerably increase the cell efficiency. Thus, cost-effective fabrication methods for this process step would help to reduce the cost per W p of silicon solar cells. Laser Chemical Processing (LCP) is based on the waterjet-guided laser (LaserMicroJet®) developed and commercialized by Synova S.A., but uses a chemical jet. This technology is able to perform local diffusions at high speed and accuracy without the need of masking or any high-temperature step of the entire wafer.We present experimental investigations on simple device structures to choose optimal laser parameters for selective emitter formation. These parameters are used to fabricate high-efficiency oxide-passivated LFC solar cells that exceed 20% efficiency.

Large area p-type PERL cells featuring local p+ BSF formed by laser processing of ALD Al2O3 layers

“…The latter is used to form, by means of pico-second (ps) laser processing, localized p þ Back-Surface-Field (BSF) regions at rear local contacts. Several approaches have been used in the past for laser doping [12][13][14]; however, in this work we focus on the use of a self-aligned process as it is used for the laser doped selective emitter technology [15]. In this way the dielectric ablation and the local-BSF are formed simultaneously by laser processing and the firing step to form the local-BSF via Al-Si alloying is not needed anymore.…”

Sheet resistance characterization of laser-doped lines on crystalline silicon wafers for photovoltaic applications

“…Laser doping has increasingly been adopted in the manufacture of high-efficiency silicon solar cells by institutions and companies worldwide [1][2][3][4][5][6][7]. The main objective is to create laser patterns on the front or rear surface.…”

Si paste technology for high-efficiency solar cells

“…In general, laser doping using liquid or solid B as the B source and nanosecond (NS) laser result in doped regions with junction depths at the order of 2 lm or less (Hallam et al, 2015;Bounaas et al, 2013;Kray et al, 2008;Kim et al, 2014a;Green, 2015). Traditional B sources require a high energy to melt the Si substrate and a long time to maintain B diffusion; hence, NS laser is the best choice.…”