Trident Solar (Brookfield, CT) and Alpha (South Plainfield, NJ), a Cookson Electronics company, have collaborated on additive, non-contact inkjet technologies that provide enhanced production yields and could increase cell efficiency up to 1% when compared to the use of traditional screen printing technologies.
The solution for direct pattern printing and etching uses Trident’s inert 256Jet-S™ inkjet printhead and Alpha’s jettable solar materials including both p and n dopants, dielectric, silver conductive metallic inks and etchants. Inkjet deposition allows for etching of very narrow feature line widths with SiNx, a-Si, or c-Si. The new technology has demonstrated an etched feature line width of 100 microns with technology development roadmap to enable production of etched features as narrow as 40 microns.
Cell efficiency is further enhanced through inkjet’s capability to etch away SiNx reflective material on photovoltaic cells in the valleys and peaks of the silicon active layer, ensuring minimal resistivity of the contact to the silicon. Inkjet can also be used to jet conductive metal inks (such as silver ink) to digitally produce contact lines with thickness, 2x-3x finer than can be produced with silver paste and rotary screen printing. The reduced contact line width reduces shadowing on the active layer enabling increased cell efficiency.
The high-resolution, direct-write printing method also saves in process steps, speeds set-up time, eliminates waste, reduces cost through automation, and enables non-contact printing for thin, sensitive substrates. Lines or holes can be produced without the damage and defects associated with lasers. Digital printing is non-contact so breakage and resulting scrap are eliminated.