David Kneeburg

A high concentration photovoltaic module utilizing micro-transfer printing and surface mount technology

We describe a high concentration photovoltaic (CPV) module utilizing micro-transfer printed (µ-TP) dual-junction GaInP/GaAs solar cells and an ELO (Epitaxial Lift-Off) process used to fabricate very small cells (<0.5 mm2) using 1st use and reused GaAs substrates. The benefits of this technology include high efficiency, simple distributed heat transfer at high concentration ratios, and short optical paths. This approach enables the use of low cost, high reliability surface mount assembly of large backplanes for integration into CPV modules. To minimize compound semiconductor use and maximize cell efficiency, we combine plano-convex primary and spherical secondary optics to concentrate sunlight 1000X over a +/−0.8 degree angle of acceptance. Receiver efficiencies of ELO dual-junction GaInP/GaAs cells of >30% at 1,000 sun concentration are reported. Coupled with a >80% efficient optical train, module efficiencies greater than 24% have been achieved with dual-junction µ-TP solar cells.

A New Approach For A Low Cost CPV Module Design Utilizing Micro‐Transfer Printing Technology

Semprius is applying a novel massively parallel, automated production process to address CPV’s reliability, performance, cost, and scalability requirements. The new design approach utilizing patented micro‐transfer printing technology enables the use of many very small cells (0.36 mm2) with benefits including high efficiency, simple distributed heat transfer, high concentration ratio, and small thin concentrating optical elements. We briefly describe the design approach and provide detailed supporting on‐sun measurements.

Pressure activated interconnection of micro transfer printed components

Micro transfer printing and other forms of micro assembly deterministically produce heterogeneously integrated systems of miniaturized components on non-native substrates. Most micro assembled systems include electrical interconnections to the miniaturized components, typically accomplished by metal wires formed on the non-native substrate after the assembly operation. An alternative scheme establishing interconnections during the assembly operation is a cost-effective manufacturing method for producing heterogeneous microsystems, and facilitates the repair of integrated microsystems, such as displays, by ex post facto addition of components to correct defects after system-level tests. This letter describes pressure-concentrating conductor structures formed on silicon (1 0 0) wafers to establish connections to preexisting conductive traces on glass and plastic substrates during micro transfer printing with an elastomer stamp. The pressure concentrators penetrate a polymer layer to form the connection, and...

On‐Sun Performance of a Novel Microcell Based HCPV System Located in the Southwest US

Semprius has developed a novel microcell based, highly scalable HCPV module that addresses performance, cost and reliability requirements for utility scale solar installations. Semprius has fabricated dual junction cell based engineering prototype modules with 1000X concentration based on this technology. A 1 kW HCPV system using these modules was installed in Tucson to validate the technology and acquire on‐sun data. Eight months of on‐sun results from this system are presented.

Micro-Transfer-Printing: Heterogeneous integration of microscale semiconductor devices using elastomer stamps

Micro-transfer-printing is an emerging method to accurately assemble microscale semiconductor devices onto non-native substrates. In micro-transfer-printing an engineered elastomer stamp coupled to a precision motion controller is utilized to pick-up and transfer arrays of microscale devices. A wide range of materials and devices have been micro-transfer-printed, including; Silicon integrated circuits, Gallium Arsenide LEDs, Gallium Arsenide solar cells, Gallium Arsenide lasers and Gallium Nitride LEDs. Devices compatible with micro-transfer-printing are very thin (<; 10 microns) and small (<; 100um lateral dimensions) and are ideally suited for making flexible device formats and are also well-suited for wafer-level heterogeneous integration. Here, we review the state-of-the art in Micro-Transfer-Printing and also present Micro-Transfer-Printing as a cost-effective approach to heterogeneous integration of compound semiconductor sensors.