New Low-Cost Manufacturing Process Produces High-Performing Intermediate Band Solar Cells
UCF researchers have invented a novel additive manufacturing system and methods for thin film fabrication specifically useful in fabricating higher performance solar photovoltaic (PV) cells at a fraction of the cost of traditional PV cell manufacturing methods. Today’s commercial solar cells are expensive to produce ($100-$400 per m2) and typically have low conversion efficiency (15-20 percent). With the new Laser‐Assisted Manufacturing Process Using Microfluidic Suspensions and Dry Powders, companies can make next-generation PVs, such as Intermediate Band Solar Cells (IBSCs), for far less (approximately $30 per m2). More importantly, IBSCs have high conversion efficiency (~50 percent).
The invention comprises a system and methods of fabricating additively manufactured structures using a roll-to-roll process technology and a unique and novel laser electrospray printhead. The inventive concept accommodates scalable large structures, wherein cylinders (feed and take-up spools) move or roll a substrate through an electrospray module. The module deposits microdroplets of nanoparticles onto the substrate through both hydrodynamic and electrodynamic shear. The electrospray module can operate in a steady cone-jet spray mode and a micro-dripping mode, depending on the manufacturing requirements. As the substrate moves, an annular laser beam dries and sinters the wet nanoparticles, fusing them onto the substrate one layer at a time. To focus the laser beam, the system uses either a hollow parabolic mirror or a hollow flat mirror and an annular lens, as required. The same concept can produce regular arrays of microdots and nanodots.
The system supports the delivery of dry powders of different materials, such as metals, ceramics, semiconductors and polymers, to an elongated (large depth-of-focus) focal region of a laser beam. The laser heats and raises the temperature of the powder to approximately 95 percent of its melting temperature until it forms into a toothpaste-like soft matter. Subsequently, the system deposits the soft matter from the focal region onto a substrate to form three-dimensional structures, as in additive manufacturing. Another variation of the system and method can be applied to bio-printing by using a suspension of biological tissues in a biofluid medium.
In an example process, a manufacturer can use the invention to produce a thin film based IBSC and structural arrays. For the thin films, the laser electrospray printhead operates in a steady cone-jet mode to deposit micro-droplets of nanoparticles onto glass or flexible substrates, such as polyimide plastics. For the structural arrays, the electrospray uses microdripping as well as the cone-jet spray mode to fabricate micro‐ and nano-dot superlattices. Rapid heating and cooling, inherent in laser processing, enables the system to heat a thin layer of materials without melting the substrate. Thus, the technology offers an advantage over other deposition techniques, especially for making solar cells on plastic substrates.
- Low manufacturing costs, high PV efficiency
- Precision nanodeposition
- Solar cell and panel production
- Semiconductor fabrication