Photovoltaic array for a power-by-light system
A hybrid-integrated series/parallel-connected photovoltaic diode array employs 10s-to-100s of single-wavelength III-V compound semiconductor photodiodes in an array bonded onto a transparent optical plate through which the array is illuminated by monochromatic light. The power-by-light system receiver enables high-voltage, up to 1000s of volts, optical transmission of power to remote electrical systems in harsh environments.
1. A power-by-light system receiver, comprising:
a photovoltaic diode array of single-junction III-V semiconductor photovoltaic diodes on an electrically insulating, optically transparent substrate, wherein a plurality of the diodes is connected in series, wherein each of the single-junction III-V semiconductor photovoltaic diode comprises an n-type window layer on the electrically insulating, optically transparent substrate, an undoped i-type absorber layer on the n-type window layer, a p-type layer on the undoped i-type absorber layer, and a continuous p-side ohmic contact covering the p-type layer, and wherein an n-side contact is to an exposed edge of the n-type window layer and metallization between the plurality of diodes connects the n-side of one diode to the p-side ohmic contact of the next diode in the series; and
a laser or a light-emitting diode providing above-bandgap monochromatic light that illuminates the photovoltaic diode array through the electrically insulating, optically transparent substrate and wherein the photovoltaic diode array converts the monochromatic light to an electrical output.
2. The receiver of claim 1 , wherein the III-V semiconductor comprises GaAs or (AlGa)As.
3. The receiver of claim 1 , wherein the III-V semiconductor comprises InGaP or GaN.
4. The receiver of claim 1 , wherein the n-type window layer comprises an (AlGa)As layer or a GaAs layer.
5. The receiver of claim 4 , wherein the (AlGa)As layer comprises a uniform AlGaAs layer, a graded AlGaAs/GaAs layer, or an AlGaAs/GaAs bilayer.
6. The receiver of claim 1 , wherein the electrically insulating, optically transparent substrate comprises sapphire.
7. The receiver of claim 1 , wherein the electrically insulating, optically transparent substrate comprises glass, fused silica, polycarbonate, or GaN.
8. The receiver of claim 1 , wherein the photovoltaic diode array is bonded to the electrically insulating, optically transparent substrate by an optically transparent polymer.
9. The receiver of claim 8 , wherein the optically transparent polymer comprises benzocyclobutene.
10. The receiver of claim 1 , wherein the plurality comprises at least one hundred diodes connected in series.
11. The receiver of claim 1 , wherein the monochromatic light comprises 808 nm wavelength laser light.
12. The receiver of claim 1 , wherein the photovoltaic diode array comprises a plurality of series and parallel diode circuits that most efficiently convert non-uniform illumination by the monochromatic light to electricity.
13. The receiver of claim 1 , wherein the plurality of diodes connected in series generate a voltage greater than 2 V.
14. The receiver of claim 1 , wherein the plurality of diodes connected in series generate a voltage greater than 1000 V.
15. The receiver of claim 14 , wherein the plurality of the diodes is connected in series to form a folded series diode loop and the bypass diode is wired in parallel across an open end of the loop.
16. The receiver of claim 1 , wherein the photovoltaic diode array further comprises a plurality of the diodes connected in parallel.
17. The receiver of claim 1 , wherein the photovoltaic diode array is less than 10 microns in thickness.
18. The receiver of claim 1 , further comprising a diffuser comprising a scattering structure that homogenizes the monochromatic light to uniformly illuminate the photovoltaic diode array through the electrically insulating, optically transparent substrate.
19. The receiver of claim 1 , further comprising at least one bypass diode wired to shunt current around at least one of the photovoltaic diodes.
20. The receiver of claim 19 , further comprising an opaque blocking layer to block light from illuminating the at least one bypass diode.
21. The receiver of claim 1 , further comprising a light distribution plate having an edge and a length disposed on a bottom surface of the electrically insulating, optically transparent substrate, wherein the light distribution plate is edge-illuminated by the monochromatic light and wherein the light distribution plate input couples the monochromatic light, transports the input-coupled light down the length by total internal reflection, and scatters at least a portion of the input-coupled light through the electrically insulating, optically transparent substrate.