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Laser, Energy and Environment

Renewable and Low-Carbon Energy production is considered as a major challenge of the 21st century. "Laser, Energy and Environment" Research at LP3 aims to study the laser processes that concern this identified priority sector. The LP3 has acquired valuable experience over the past decade on laser processes for Photovoltaics and laser cleaning and decontamination of particles for the ITER project.

This experience has allowed the LP3 to become a valuable laser partner for a community involved in clean energy production and addressing our changing environment and biodiversity.

Laser texturization

’Black silicon’, instead of a shimmery gray appearance of normal silicon, looks black, because less light bounces off its surface. Technically, black silicon refers to silicon wafers with billions of high aspect ratio, micro/nano-sized features fabricated on the surface, which effectively trap a larger percentage of photons by preventing light from being reflected. The enhanced light absorption due to reduced reflection is identified over the entire visible spectrum. This absorption can be also extended to the infrared spectrum, by incorporating specific dopants during the laser process. This "hyperdoping" of silicon makes this material particularly interesting in various applications such as photodetectors, thermal imager and high efficiency solar cells. This laser texturization is a chemical-free process that does not require the traditional use of strong acids, alkaline solutions, isopropanol or DI Water, and is a single step (no need for ARC anti-reflection coating) clean process. The LP3 has a strong collaboration with the Mazur Group (Harvard), specialized in black silicon applications.

Ongoing research is designed to reveal the microstructure transformation from initial silicon surface to the micro-cones or so-called "penguin-like" structures that are identified on black silicon surface, with increase number of deposited laser pulses. These results are on the other hands taken as input for numerical model developing at LP3, where light coupling, modulation of electro-magnetic fields and surface plasmons are being taken into account. The models, once developed, will in turn help interpret experimental observations and shed lights on directions follow which future efforts will be made.

To build solar cell and generate electricity out of black silicon, a lot of technical barriers need to be overcome and the approach to tackle these obstacles will be innovative. Although efficient light trapping at black silicon surface means sunlight can be largely absorbed, to turn this light energy into electricity and harness it, a dedicated design with perfect balance among damage-less texturisation, implementation of junction and metallisation still has to be reached.

Other laser applications for photovoltaics
The LP3 has been involved in the European FP7-SOLASYS program "Next generation solar cell and module laser processing systems" coordinated by the Fraunhofer-ILT, together with industrials and academic partners (Trumpf Laser, Laserline, Manz Automation, SCANLAB, Solland Solar, BP Solar, Energy Solutions, IMEC).

The goal of this program was to benchmark laser processes for the photovoltaics industry such as : Laser ablation of dielectric coating on solar cells, Laser doping for selective emitter formation, Edge isolation with ultra-short pulse lasers, Laser high speed drilling for modern cell concepts…

Source : NEXCIS

The LP3 is also currently involved in laser processes for new generations of thin films solar panels including CIGS Cells (projects : AMIDEX PHOTOLASE, H2020 ALABO…)

Contact : Thierry SARNET