Solar cell efficiency improvement using dip-pen nanolithography

An innovative approach to improve the performance of photovoltaic solar cells is presented. Until recently, the fabrication of grating layers has been well proven using bulk micromachining techniques, but lately low-cost dip-pen nanolithography (DPN) has been proposed as a method for printing nanostructures on different substrates and has matured to become one of the most versatile patterning techniques available at the nanoscale. However, this technique has scarcely been studied and tested for fabricating grating layers. In this research, submicron grating patterns from high refractive index polymers are fabricated on a few types of solar cells, significantly improving their efficiency. The appropriate geometries and materials for the grating patterns are obtained via numerical optimization using rigorous coupled wave analysis for electromagnetic simulations of the grating multilayer. Possible light-confinement schemes are analyzed, and their figures of merit are assessed. The simulation of the electrical characteristics is integrated with postdesign electromagnetic simulation. The corresponding theoretical and experimental studies shed light on the impact of the merger of the grating structure with the light harvester on the device’s optical and electrical properties. Success in using DPN paves pathways to low-cost fabrication of light harvesting devices with improved performance.