Silicon ink selective emitter process: Optimization of selectively diffused regions for short wavelength response

The Innovalight Cougar^™ Platform is a portfolio of simple to implement technologies that, when combined with Innova-light Silicon Ink, enables the manufacture of a selective emitter solar cell with a non-masking single-step diffusion. Cell efficiencies of up to 19% have been achieved. Innova-light Silicon Ink is a highly engineered silicon nanoparticle colloidal dispersion, implemented for both high volume ink-jet and screen deposition, and further optimized to be produced and delivered in commercial volumes. A particular feature of the selective emitter structure is its enhanced quantum efficiency in the short wavelength region as result of reduced emitter recombination. In this report we demonstrate how the properties of the selectively doped regions on the front surface of the cell affect the short wavelength response of a Cougar cell. In particular, the importance of the emitter dopant profile for minimizing emitter recombination and the broad processing window of the Cougar cell structure with respect to emitter doping are illustrated. Further, the effect of the ink finger width on the short-wavelength response of the cell and the trade-off between the loss of short circuit current (J_sc) and metal-to-ink pattern alignment are demonstrated.