Last week, JA Solar and Innovalight jointly announced a partnership to develop Innovalight’s cell design “using silicon ink technology and conventional silicon wafers,” which has already shown 18% cell efficiencies. As we outlined in the latest Innovalight briefing (see the February 19, 2009 LRSJ), this technology is likely a take-off on Sanyo’s “heterojunction with intrinsic thin layer” (HIT) cells. In these cells, Sanyo adds thin layers of intrinsic (undoped) and p-type (positive-charge-carrying) amorphous silicon (a-Si) on one side of a high quality n-type (negative-charge-carrying) monocrystalline (c-Si) wafer, and intrinsic and n-type a-Si layers on the other. In doing so, it makes the crystalline silicon wafer into a multi-junction solar cells, increasing the range of light it can absorb and convert into electricity – achieving cell efficiencies up to 22%. Though the details of its approach are unconfirmed, Innovalight may print p-doped, n-doped, and intrinsic silicon nanoparticles onto monocrystalline wafers, followed by an annealing process to complete the cell structure. The partnership with JA Solar is a boon for Innovalight, which struggled to commercialize applications based on its silicon nanoparticles since 2002. While the development and qualification process will be long for the new cell design, JA Solar’s participation is the best vote of confidence thus far of Innovalight’s technology.
Also last week, Kaneka – a leading thin-film silicon module producer – announced that it will invest ¥1.5 billion ($16.4 million) in a three-year agreement with leading European research institute IMEC to develop solar cells based on a “hybrid” of crystalline silicon solar cells and amorphous silicon, with the target of 20% cell efficiency within three years. Once again, the announcement strongly suggests that Kaneka and IMEC will pursue a cell concept similar to Sanyo’s HIT cells. The participation of IMEC suggests that Kaneka will also pursue nanoparticle (or non-vacuum deposition) routes to a HIT-style cell structure. With Sanyo’s HIT cell patents expiring in the next several years, the HIT cell concept offers an attractive option for crystalline silicon cell developers to boost their efficiencies with a well-known design. As competition in the crystalline silicon module market intensifies throughout 2010 and 2011, clients should expect lots of cell developers to pursue alternative crystalline silicon structures – including the HIT cell, emitter wrap-though, and back contact cell designs – “behind the scenes” in the effort to gain market share in the high-efficiency, high-power-density residential and commercial rooftop markets.
