Polymethylmethacrylate as an Anti-Reflective Coating for Enhancing Solar Cells Efficiency Using Dip-Pen Nanolithography

Evyatar Rimon, Electrical and computer engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Roy Avrahamy, Electrical And Computer Engineering, Ben-gurion University Of The Negev, Beer-sheva, Israel
Moshe Zohar, Electrical And Electronics Engineering, Shamoon College Of Engineering, Beer-sheva, Israel
Zeev Fradkin, Electrical And Electronics Engineering, Shamoon College Of Engineering, Beer-sheva, Israel
Rafi Shikler, Electrical And Computer Engineering, Ben-gurion University Of The Negev, Beer-sheva, Israel
Shlomo Hava, Electrical And Computer Engineering, Ben-gurion University Of The Negev, Beer-sheva, Israel

Dip-pen nanolithography (DPN) is a scanning probe lithography technique, involving the use of a cantilever tip which is similar to the atomic force microscope (AFM) tip. The cantilever tip is used to create patterns directly onto various surfaces by transferring an ink selected from a variety of inks, which is then bonded irreversibly to the substrate [1-4].

Uniform patterning utilizing DPN technique requires optimal conditions affected by many parameters. This is due to the direct transfer of materials to the patterning surface and the chemical interaction between them [5].

Recently, nanostructures have been considered as light-trapping coatings for ultrathin solar cells [6]. One of the physics-based approaches aimed at improving PV cell efficiency is by smartly applying EM theory of light when choosing the right coating materials, and by engineering the surface patterns to reduce sunlight reflection and to provide light confinement inside the cell, thus increasing the number of absorbed photons.

In this work, we demonstrate a new approach for developing a low-cost, anti-reflective coating using Polymethylmethacrylate (PMMA) based inks for the patterning of grating layer structures on a silicon (Si) wafer surface. The patterning procedures were performed at a temperature of 23^oC, as we were examining the effect of different parameters over the patterning. We optimized the printing process by adjusting the humidity, dwell time of the tip on the surface and the ink composition.