Manufacturing of High-Efficiency Perovskite Solar Cells via Coupled Ion Source and Magnetron Discharges

Michigan State University, East Lansing MI

Investigators

Abstract

This award supports fundamental research that contributes new knowledge to enable the manufacturing of high-efficiency perovskite solar cells, promoting the generation and use of clean energy thus advancing national prosperity. Perovskite solar cells are emerging photovoltaic devices and have recently achieved power conversion efficiencies exceeding 25 percent. A critical component of perovskite solar cells is a transparent conductive oxide thin film of about 100 nanometer thickness, which acts as the top electrode to collect the photocurrent while allowing light to pass through. The perovskite layer underneath the top electrode is heat-sensitive and demands room-temperature deposition of the transparent conductive film. However, oxide thin films grown at room temperature by conventional magnetron sputtering – the standard industrial technology used for manufacturing thin films – have amorphous structures that result in poor electrical conductivity and low optical transmittance. This challenge has become a critical barrier limiting the energy conversion efficiencies of perovskite solar cells. This project advances the knowledge of plasma discharges to enable ion-beam-enhanced soft sputtering, which permits room-temperature growth of highly transparent and conductive oxide thin films that significantly enhance solar cell efficiency and performance. The broad use of renewable energy supports a sustainable economy and addresses global environmental concerns. This project integrates multidisciplinary research and training activities for graduate and undergraduate students and prepares them for a highly skilled future workforce. Besides advanced manufacturing, the project advances the field of plasma physics. This award also supports NSF's ECosystem for Leading Innovation in Plasma Science and Engineering (ECLIPSE) program. Highly transparent and conductive oxide thin films, such as indium-tin-oxide (ITO), have polycrystalline structures that could not be formed under off-phase-equilibrium conditions at low temperatures in classical physical vapor deposition. This research aims to validate the hypothesis that the interactions of an ion beam with the surface atoms are equivalent to localized heating at the atomic scale. Realizing effective ion-atom interactions requires overcoming the scientific barriers to creating a high-density soft low energy ion beam that is effectively coupled with magnetron sputtering. This research fills the knowledge gap on the energy distributions of the ion beam and the sputtered atoms under the coupled plasma discharges. The research team performs self-consistent particle-in-cell Monte Carlo simulations of the beam plasma source and magnetron sputtering, develops a model to elucidate the mutually enhanced ion-film and ion-target interactions, establishes the relationships between the plasma parameters and the resulting film microstructures and properties, and demonstrates high-efficiency perovskite solar cells. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.