Liquid Phase Crystallization (LPC)
In order to compete with traditional wafer-based PV modules a novel silicon thin-film technology is needed. Thin (5 – 20 micrometers), polycrystalline silicon on glass an attractive candidate because it combines the advantages of wafer-based PV (high material quality, established process know-how) and thin-film technology (low cost, low material demand, integrated series connection of modules).
The liquid phase crystallization technology (LPC) developed at HZB in cooperation with Hamburg University of Technology (TUHH) is capable to form polycrystalline silicon layers on glass that exhibit wafer equivalent electronic quality. Due to directional solidification, the formed grains are up to cm in length and mm in width. The high electronic quality is reflected in open circuit voltages up to 661 mV.
Considering the excellent LPC material quality and the still early stage of development of this approach, conversion efficiencies of 18% or more for single-junction cells seem realistic. However, for a successful commercialization of this technology maximizing the material efficiency is not enough. At the same time the scalability and cost benefit has to be demonstrated. Therefore, research on LPC at the Institute Silicon Photovoltaics is structured in two sub-topics:
- High-efficiency cells and material development
- Low-cost processes and mini-modules