Optical systems fabricated by printing-based assembly
View Patent ↗Provided are optical devices and systems fabricated, at least in part, via printing-based assembly and integration of device components. In specific embodiments the present invention provides light emitting systems, light collecting systems, light sensing systems and photovoltaic systems comprising printable semiconductor elements, including large area, high performance macroelectronic devices. Optical systems of the present invention comprise semiconductor elements assembled, organized and/or integrated with other device components via printing techniques that exhibit performance characteristics and functionality comparable to single crystalline semiconductor based devices fabricated using conventional high temperature processing methods. Optical systems of the present invention have device geometries and configurations, such as form factors, component densities, and component positions, accessed by printing that provide a range of useful device functionalities. Optical systems of the present invention include devices and device arrays exhibiting a range of useful physical and mechanical properties including flexibility, shapeability, conformability and stretchablity.
1. A method of making an integrated optical device comprising the steps of:
transfer printing a plurality of printable semiconductor elements to a device substrate; and
addressing an optical component or an array of optical components with the plurality of printable semiconductor elements on the device substrate, wherein each of the plurality of printable semiconductor elements are optically addressed to the optical component or to a unique individual member of the array of optical components;
wherein the transfer printing comprises the steps of:
contacting an array of solar cells on a wafer with a stamp contact surface;
removing the stamp in a direction away from the wafer to transfer the array of solar cells from the wafer to the stamp contract surface;
transferring the array of solar cells from the stamp contact surface to a back electrode supported by a target assembly substrate;
wherein the method further comprises the steps of:
providing an insulating layer and front electrodes in electrical contact with the transferred array of solar cells; and
addressing an array of microlenses with the transferred array of solar cells, wherein each microlens in the array is individually addressed and optically aligned with an individual solar cell.
2. The method of claim 1 , wherein the array of microlenses is a molded array of microlenses.
3. The method of claim 1 , wherein the microlenses comprise concentrating lenses to focus incident light on a solar cell to which the microlens is individually addressed.
4. The method of claim 1 , wherein the solar cells are a multilayer structure comprising:
an antireflection layer;
a top contact that traverses the antireflection layer;
a p-n junction in electrical contact with the top contact; and
a bottom layer that supports the p-n junction.
5. The method of claim 1 , wherein the microlenses comprise collectors to optically focus light to solar cells, wherein each microlens-solar cell individually addressed pair has a collector area to solar cell area ratio that is greater than or equal to 400.
6. The method of claim 5 , wherein the collectors have an individual size that is about 2 mm and the solar cells have an individual size that is about 0.1 mm.
7. The method of claim 1 , wherein the array of microlenses is made by replica molding.
8. The method of claim 7 , wherein the array of microlenses comprises a plano-concave polymer lens array.
9. The method of claim 1 , wherein the array of microlenses comprises Fresnel lenses.
10. The method of claim 1 , wherein the array of microlenses comprise horizontal light pipes, waveguides, or both horizontal light pipes and waveguides.
11. The method of claim 1 , wherein the solar cells comprise silicon solar cells made from a silicon on insulator wafer.
12. The method of claim 1 , wherein the solar cell comprises a doped top surface with a P/As mixture supported by a buried oxide layer.
13. The method of claim 1 , further comprising the steps of:
casting the insulating layer on the printed solar cells, thereby planarizing the printed solar cells; and
depositing the top electrodes on the planarized printed solar cells.
14. The method of claim 1 , wherein the stamp is an elastomeric stamp.
15. The method of claim 1 , wherein the front electrodes are aligned in a direction that is perpendicular to the transferred array of solar cells to minimize shadowing of solar cells by the front electrodes.
16. The method of claim 15 , wherein the front electrodes optically obstruct a lateral distance of an underlying solar cell, wherein the optically obstructed lateral distance is less than 60 μm for a solar cell having a length greater than about 1 mm.
17. The method of claim 1 , wherein at least 1000 micro solar cells are transfer printed in parallel.
18. The method of claim 1 , wherein the plurality of printable semiconductor elements are part of:
a light emitting diode (LED) addressed to a diffusing optical lens;
a vertical-cavity surface-emitting laser (VCSEL) addressed to an optical fiber;
a photodiode addressed to a collecting optical lens; or
an optical sensor and an optical generator addressed to a collecting lens.
19. The method of claim 1 , wherein the device substrate is a thin and flexible substrate and the transferred semiconductor elements are part of an LED having a thickness less than or equal to 0.3 mm and greater than or equal to 0.0003 mm to provide a conformable LED lighting system.
20. An optical system comprising:
a device substrate;
a plurality of device components supported by the device substrate, wherein each device component comprises a printable micro-solar cell; and
an array of optical components comprising an array of collecting optical lens to concentrate light on the micro-solar cells, wherein each member of the array of optical components is optically addressed to a unique member of the plurality of device components;
wherein each collecting optical lens has a collector area and each micro-solar cell has a solar cell area, and a ratio of the collector area to the solar cell area is greater than or equal to 400.
21. The optical system of claim 20 , wherein the optical components comprise a polymer lens array.