I-Corps: High-value surface modifications with nanomaterial thin films

South Dakota State University, Brookings SD

Investigators

Abstract

This I-Corps project aims to demonstrate the commercial viability of using highly reflective and light scattering nanoparticle thin films as solar cell back reflectors with the goal to replace high-vacuum processing techniques. Back reflectors can enhance the solar cells photocurrent by 30%, but conventional back reflectors consist of sputtered metal films. Large scale production sputtering systems require high capital cost and frequent downtime due to system maintenance and target replacement. In addition to the high cost, silver back reflectors used in record efficiency solar cells cannot be used in commercial products due to poor adhesion, oxidation, and migration into the cell resulting in deteriorated performance and reliability. Instead, aluminum back reflectors are used, but only results in moderate performance improvements due to poor reflectance in the most critical portion of sunlight. This project uses the electrophoretic deposition method using novel solutions to grow dielectric nanoparticle films, which will reduce the cost of producing back reflectors due to reduced capital expense devoted to building out the processing facilities and reduced operating expense through less down time, more efficient coating material utilization, and reduced energy consumption. A broad market opportunity exists for technologies that add high-value functionality to otherwise low-value surfaces, e.g. superhydrophobic surface coatings for self-cleaning applications, photonic structures for light management, textured/porous structures for electronic devices. Conventional methods to obtain high-value surfaces typically require chemical wet-etching, high-vacuum, and lithography methods, and consequently, rarely make it out of the lab and into commercially-viable products. The proposed innovation is to use nanoparticle-based films deposited by the low-cost, ?green?, scalable, and industry-relevant electrophoretic deposition method, which could bring value-added technologies to market. An application identified for the nanoparticle films is a solar cell back reflector. Competitive solar technologies require both high conversion efficiencies and low-cost manufacturing techniques. If successfully deployed, the proposed technology is expected to enable solar manufacturers a lower cost alternative to high-vacuum sputtered metal back reflectors for high efficiency and stable solar cells.