Your daily dose of Photovoltaic Technology Developments and Solar News

ABSTRACT
A vast majority of silicon solar cells are manufactured using silver paste that is screen printed onto the front side of the wafer and fired to form the front-side contact. Though this method is well established within the industry, it continues to present several areas for potential efficiency improvements. The Fraunhofer Institute has, among others, studied the potential of using electrodeposition of silver on top of the front side silver paste as a way to improve the frontside contact and increase cell efficiency.

ABSTRACT

The use of perfluorinated gases such as NF₃, CF₄ or SF₆ for PECVD (plasma enhanced chemical vapor deposition) chamber cleaning has a much higher impact on global warming than does the use of onsite-generated F₂. This holds true even when supposing that in the future much more effort is paid for the correct abatement and a leak-free supply and take-back chain. This paper will discuss the steps available to the PV industry for control and reduction of carbon emissions in the chamber cleaning process.

By Guy Beaucarne, Patrick Choulat, B.T. Chan, Harold Dekkers, Joachim John & Jef Poortmans, IMEC, Belgium -

ABSTRACT -
Si etch processes are vital steps in Si solar cell manufacturing. They are used for saw damage removal, surface texturing and parasitic junction removal. The next generation of Si solar cells, featuring thinner wafers and passivated rear surfaces, will pose more stringent demands on those steps. Surface decoupling (achieving different surface treatments on the front and the rear) has to be achieved while minimizing Si consumption. Plasma texturing is an emerging technique that appears very promising in that respect, as efficiencies as high as 17.4 % have been achieved on screenprinted multicrystalline Si solar cells incorporating this process.

By Dorit Linaschke, Mattias Leistner, Gerrit Mäder, Wulf Grählert, Ines Dani & Stefan Kaskel, Fraunhofer IWS,Dresden, Germany

ABSTRACT

The etching technology currently used in the solar industry is mostly based on wet chemical processing. Plasmaenhanced dry chemical etching at atmospheric pressure is an alternative to the existing technology, especially when combined with similar process technologies, for example plasma-enhanced deposition techniques at atmospheric pressure, to provide a continuous in-line processing of crystalline silicon solar cells. This paper presents the use of plasma chemical etching using Fourier Transform infrared (FT-IR) spectroscopy to monitor different silicon wafer processing steps as an alternative to the widely used wet chemical processing approach.

By Hubert-Joachim Frenck, Q-Cells AG, Bitterfeld-Wolfen, Germany

ABSTRACT
Ever since the introduction of attractive feed-in tariffs for photovoltaic electricity generation, there has been a huge surge in all kinds of photovoltaic applications. Products based on multicrystalline wafers still have the largest market share with thin-film products picking up in recent times. In the course of this process, production technology for waferbased solar cells has been improved. With the second generation of tools, a trend towards standardization is apparent. Deposition of silicon nitride is one of the key processes of solar cell production. While its technological significance is often underestimated, it is the only process step that serves a multitude of purposes.

Liquid-borne acoustic energy in the frequency range from 350kHz to approximately 5MHz is becoming increasingly useful in a number of cleaning applications that require processing of extremely delicate parts and assemblies to remove particles ranging from a few microns down to a fraction of a micron in size.