University of Michigan

Forrest, Stephen R.

Lee, Kyusang

Shiu, Kuen-Ting

Zimmerman, Jeramy

Kyusang Lee

Stephen R Forrest

Jeramy David Zimmerman

Dejiu Fan

Kuen-Ting Shiu

Max Shtein

Andrej Lenert

Byungjun Lee

Tobias Eugene Burger

Peicheng Ku

Aaron Lamoreux

Boning Qu

Matthew Shlian

Chih-Wei Chien

Deiju Fan

A method of fabricating a multi-junction photosensitive device is provided. The method may include fabricating at least two photoactive layers, wherein at least one photoactive layer is fabricated on a transparent substrate, and at least one photoactive layer is fabricated on a reflective substrate, patterning at least one optical filter layer on at least one photoactive layer fabricated on a transparent substrate, and bonding the at least two photoactive layers using cold weld or van der Waals bonding. A multi-junction photosensitive device is also provided. The device may have at least two photoactive layers, and at least one optical filter layer, wherein at least two layers are bonded using cold weld or van der Waals bonding. The optical filter layer may be a Distributed Bragg Reflector.

Mechanically stacked tandem photovoltaic cells with intermediate optical filters

Thermophotovoltaic (TPV) systems and devices with improved efficiencies are disclosed herein. In one example, a thermophotovoltaic (TPV) cell includes an active layer; a back-surface reflective (BSR) layer; and a spacer layer positioned between the active layer and back-surface reflective layer.

Thin-film thermophotovoltaic cells

The present disclosure relates to compound parabolic concentrators. In one implementation, a compound parabolic concentrator may include a parabolic array having a base, a side wall, and an aperture for receiving light and a dielectric layer having a refractive index. In another implementation, a stacked compound parabolic concentrator may include a parabolic array having a base, a side wall, and an aperture for receiving light and multiple dielectric layers within the array. Each dielectric layer may have a refractive index, and the refractive index may decrease with each dielectric layer moving from the base of the parabolic array to the light receiving aperture.

Stacked compound parabolic concentrators integrated with multiple dielectric layers for wide acceptance angle

A method is presented for fabricating a substrate comprised of a compound semiconductor. The method includes: growing a sacrificial layer onto a parent substrate; growing an epitaxial template layer on the sacrificial layer; removing the template layer from the parent substrate using an epitaxial lift-off procedure; and bonding the removed template layer to a host substrate using Van der Waals forces and thereby forming a compound semiconductor substrate.

Preparation of compound semiconductor substrate for epitaxial growth via non-destructive epitaxial lift-off

Thin-film electronic devices such as LED devices and field effect transistor devices are fabricated using a non-destructive epitaxial lift-off technique that allows indefinite reuse of a growth substrate. The method includes providing an epitaxial protective layer on the growth substrate and a sacrificial release layer between the protective layer and an active device layer. After the device layer is released from the growth substrate, the protective layer is selectively etched to provide a newly exposed surface suitable for epitaxial growth of another device layer. The entire thickness of the growth substrate is preserved, enabling continued reuse. Inorganic thin-film device layers can be transferred to a flexible secondary substrate, enabling formation of curved inorganic optoelectronic devices.

Fabrication of thin-film electronic devices with non-destructive wafer reuse

A solar tracking system for tracking the orientation of solar energy is disclosed. The solar tracking system may be integrated with solar cells and solar concentrators. The solar tracking system may have a first () and second () tracker module array that are opposite from another, aligned in substantially identical orientation, and form a tracker module pair array (). Tracker module pairs () may allow motion relative to one another while maintaining substantially identical orientation. Solar concentrators may be attached to opposing tracker modules of a tracker module pair forming an array of solar concentrators. A base bar array () may be coupled to at least one tracker module pair. A transmission may operably rotate the base bar array and the tracker module pair array simultaneously.

Solar tracking system

A method of fabricating a photovoltaic cell having a microinverter is provided. The method may include fabricating a monolithic microinverter layer through epitaxy and operably connecting the at least one microinverter layer to at least one photovoltaic cell formed on a photovoltaic layer. A photovoltaic device is also provided. The device may have a photovoltaic layer comprising at least one photovoltaic cell and a microinverter layer comprising at least one microinverter, wherein the microinverter layer was fabricated through epitaxy, the at least one microinverter is configured to be operably connected to at least one photovoltaic cell.

Device and method of monolithic integration of microinverters on solar cells

The present disclosure relates to methods and growth structures for making thin-film electronic and optoelectronic devices, such as flexible photovoltaic devices, using epitaxial lift-off (ELO). In particular, disclosed herein are wafer protection schemes that preserve the integrity of the wafer surface during ELO and increase the number of times that the wafer may be used for regrowth. The wafer protection schemes use growth structures that include at least one superlattice layer.

Non-destructive wafer recycling for epitaxial lift-off thin-film device using a superlattice epitaxial layer

There is disclosed Kirigami-inspired structures for use in solar tracking applications. When coupled with thin-film active materials, the disclosed microstructures can track solar position and maximize solar power generation. In one embodiment, there is disclosed a photovoltaic system comprising a single-axis, or multi-axis solar tracking structure comprising a support structure made of a flexible material having a defined unit cell structure, and a flexible photovoltaic cell disposed on the support structure. There is also disclosed methods of making such structures in which the photovoltaic cell is mounted to the support structure by a direct-attachment bonding processes such as cold-welding.

Autonomous solar tracking in flat-plate photovoltaic panels using kirigami-inspired microstructures

Disclosed herein are methods to eliminate or reduce the peeling-off of epitaxial lifted-off thin film epilayers on secondary host substrates that allow for the fabrication of high yield ELO processed thin film devices. The methods employ patterned strain-relief trenches.

Strain relief epitaxial lift-off via pre-patterned mesas

Devices including organic and inorganic LEDs are provided. Techniques for fabricating the devices include fabricating an inorganic LED on a parent substrate and transferring the LED to a host substrate via a non-destructive ELO process. Scaling techniques are also provided, in which an elastomeric substrate is deformed to achieve a desired display size.

Devices combining thin film inorganic LEDs with organic LEDs and fabrication thereof

The present disclosure generally relates to thin film liftoff processes for use in making devices such as electronic and optoelectronic devices, e.g., photovoltaic devices. The methods described herein use a combination of epitaxial liftoff and spalling techniques to quickly and precisely control the separation of an epilayer from a growth substrate. Provided herein are growth structures having a sacrificial layer positioned between a growth substrate and a sacrificial layer. Exemplary methods of the present disclosure include forming at least one notch in the sacrificial layer and spalling the growth structure by crack propagation at the at least one notch to separate the epilayer from the growth substrate.

Thin film lift-off via combination of epitaxial lift-off and spalling

There is disclosed a method of preparing a photovoltaic device. In particular, the method comprises making thin-film GaAs solar cells integrated with low-cost, thermoformed, lightweight and wide acceptance angle mini-CPCs. The fabrication combines ND-ELO thin film cells that are cold-welded to a foil substrate, and subsequently attached to the CPCs in an adhesive-free transfer printing process. There is also disclosed an improved photovoltaic device made by the disclosed method. The improved photovoltaic device comprises a thin-film solar integrated with non-tracking mini-compound parabolic concentrators, wherein the plastic compound parabolic concentrator comprise two parabolas tilted at an angle equal to the acceptance angle of the compound parabolic concentrator.

Epitaxial lift-off processed GaAs thin-film solar cells integrated with non-tracking mini-compound parabolic concentrators

There is disclosed a method of preparing a photovoltaic device. In particular, the method comprises integrating epitaxial lift-off solar cells with mini-parabolic concentrator arrays via a printing method. Thus, there is disclosed a method comprising providing a growth substrate; depositing at least one protection layer on the growth substrate; depositing at least one sacrificial layer on the protection layer; depositing at least one photoactive cell on the sacrificial layer; etching a pattern of at least two parallel trenches that extend from the at least one photoactive cell to the sacrificial layer; depositing a metal on the at least one photoactive cell; bonding said metal to a host substrate; and removing the sacrificial layer with one or more etch steps. The host substrate can be a siloxane, which when rolled, can form a stamp used to integrate solar cells into concentrator arrays. There are also disclosed a method of making a growth substrate and the growth substrate made therefrom.

Growing community of inventors

Ann Arbor, MI, United States of America

Kyusang Lee