All Inorganic Plasmon-Enhanced Photovoltaics with Eutectic Composition

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Institution: University of Michigan Ann Arbor Title: All Inorganic Plasmon-Enhanced Photovoltaics with Eutectic Composition Intellectual Merit Most silicon-based photovoltaic devices require pure crystalline silicon as the base material, which is costly to produce through current crystal growth processes. Crystal growth of lamellar heterojunctions via eutectic solidification of earth-abundant materials (e.g. silicon, magnesium, iron) has the potential to circumvent the costly crystallization processes used to purify the silicon feedstock, and allow for enhanced minority carrier collection. Ultimately, this will result in low-cost solar cells based on earth-abundant materials. In addition, the manufacture of bulk nanostructured crystals by eutectic solidification can be accomplished at a scale commensurate with that of pure crystalline silicon used in current photovoltaic devices. The proposed research will focus on the growth and characterization of low cost, and high efficiency plasmon-enhanced heterojunction solar cells through eutectic solidification and block copolymer nanolithography. Eutectic solidification causes the self assembly of lamellar or rod-like domains with length scales from hundreds of nanometers to micrometers, which are ideal for the efficient extraction of minority carriers in metallurgical grade (impure) materials. To date, no inorganic solar cells have been constructed with eutectic composition. It is expected that earth abundant, metallurgical grade materials with eutectic composition, combined with plasmon-enhanced optical absorption, could possibly lead to the development of a new class of low-cost and high efficiency thin film solar cells. The proposed research will study the controlled growth and electrical doping of bulk crystals of impure silicide−silicon heterojunctions with nanostructured eutectic composition in an induction furnace, and characterize the nanostructured crystal structure and minority carrier diffusion length of these materials. The nanostructured eutectic materials will then be integrated into working solar cell devices. The effects of nanostructured eutectic material composition and lamellar heterojunction spacing on solar cell efficiency will be studied to gain fundamental understanding of the device performance. Plasmonic materials will also be incorporated into these devices to enhance light absorption, leading to potentially higher solar energy conversion efficiency. These plasmonic materials include highly ordered arrays of silver nanoparticles generated by block copolymer nanolithography. Broader Impacts The proposed education and outreach activities seek to increase the numbers of underrepresented minorities to enter science, technology, engineering, and mathematics (STEM) disciplines. Several hands-on demonstrations, featuring batteries and solar cells, will be made available to students at Cass Technical High School in downtown Detroit, Michigan. Two top-performing high school students will be selected to participate in the proposed research during the summer. Outreach efforts also include participation in a five-week, Detroit Area Pre-College Engineering Program that encourages junior high students to pursue careers in the sciences.