Method for laser-assisted manufacturing

#The ability to create thin films, in addition to 2-D and 3-D structural arrays of functional materials, addresses a technological need for many applications, including: flexible electronics, bio-sensing, optical coatings, energy conversion/harvesting, and data storage. Accordingly, high-resolution, scalable techniques that can achieve mass production of printed patterns using a variety of functional inks are currently needed in the art.

#Microfluidic manufacturing process are known in the art for the fabrication of additively manufactured structures, such as Intermediate-Band Solar Cells (IBSCs). IBSCs incorporate an intermediate energy band that is partially filled with electrons within the forbidden bandgap of a semiconductor and are designed to provide a large photogenerated current, while maintaining a high output voltage. Photons having insufficient energy to advance electrons from the valence band to the conduction band use the intermediate energy band to generate an electron-hole pair. Nanostructured materials and microfluidic manufacturing processes have been employed in the practical implementation of intermediate-band devices, although manufacturing challenges remain.

#Accordingly, what is needed in the art is an improved system and method for additive manufacturing that overcomes the challenges of the fabrication of new architecture

#For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which:

#FIG. 1 illustrates an exemplary intermediate band solar cell (IBSC) device that can be manufactured with the laser-assisted microfluidics manufacturing process of the present invention.

#FIG. 2 illustrates an integrated manufacturing process of thin films, wherein a wet layer of nanoink is deposited on the substrate by electrospray operated in steady cone-jet spray mode and sintered by a laser sheet, in accordance with an embodiment of the present invention.

#In various embodiments, the present invention provides a novel additive manufacturing technique that overcomes the challenges of the fabrication of various devices. In one embodiment, a new generation photovoltaic (PV) cell that may be fabricated using the laser-assisted manufacturing process of the present invention is an intermediate band solar cell (IBSC).

#FIG. 1 illustrates an exemplary embodiment of a new architecture of an IBSC 100, wherein each layer of the cell is fabricated one at a time by the deposition of nanoparticles through electrospray technology followed by sintering using a laser beam. As shown in FIG. 1, the IBSC 100 includes various thin film layers fabricated on a substrate 105 having a metal back contact 110. The thin film layers include an n+-SiC (silicon carbide) contact layer 110, an n-SiC base layer 117 and a barrier layer 120. As described in detail below, the thin film layers are fabricated by operating a laser-assisted printhead in a steady cone-jet spray mode. An intermediate band region 125 is then formed on top of the plurality of thin film layers. The intermediate band region 125 includes and n-type Si nanodot superlattice 130 comprising layers of nanodots arrays separated by a thin film. As described in detail below, the nanodots are fabricated by operating a laser-assisted printhead in a micro-dripping mode. Following the deposition of the intermediate band region 125, a thin film p-SiC emitter 135, a p+-SiC contact 140 and an electrode 150 are subsequently deposited to complete the IBSC.

#In various embodiment, the nanoparticles (e.g. 3C—SiC) can be deposited as thin films at low temperatures on glass as well as flexible substrates, such as polyimide (Kapton) plastics, because of the large diffusion coefficient and low melting temperature of the nanoparticles in comparison to that of the corresponding bulk material. The same concept can also be used for deposition of structural arrays, thereby allowing for the fabrication of the intermediate band region of the IBSC. The superlattice can be formed by placing Si nanodots 130 and each layer of nanodots can be covered with a 3C-SiC barrier layer 120, as shown in the solar cell of FIG. 1.