Electrophoretic deposition (EPD) of radioisotope and phosphor composite layer for hybrid radioisotope batteries and radioluminescent surfaces
An electrophoretic deposition (EPD) process forms a radioluminescent phosphor and radioisotope composite layer on a conductive surface of a substrate. In the composite layer formed, the particles of radioisotope are homogeneously dispersed with the radioluminescent phosphor. The radioisotope may be a beta-emitter, such as Ni-63, H-3, Pm-147, or Sr-90/Y-90. By applying the composite layer using the EPD process, the electrode can be configured for betavoltaic, beta-photovoltaic and photovoltaic cells according to further embodiments. A direct bandgap semiconductor device can convert betas and/or photons emitted from composite layer. Methods and choice of materials and components produces a hybrid radioisotope battery, conversion of photons and nuclear decay products, or radioluminescent surfaces.
1. A method for forming a phosphor and radioisotope composite layer on a substrate by an electrophoretic deposition (EPD) process comprising:
placing a substrate formed of conductive material and a counter electrode into a container;
filling the container with an electrolyte solution having radioluminescent phosphor particles and radioisotope particles dispersed therein;
connecting the conductive substrate and the counter electrode to a power supply; and
performing EPD by applying a voltage to the conductive substrate and the counter electrode to apply the composite layer of radioluminescent phosphor with radioisotope particles homogeneously dispersed therein to the conductive substrate.
2. The method of claim 1 , wherein the radioisotope is a beta-particle emitter.
3. The method of claim 2 , wherein the beta-emitter radioisotope comprises Ni-63, H-3, Pm-147, or Sr-90/Y-90.
4. The method of claim 1 , wherein the radioisotope is part of an inorganic or organic compound.
5. The method of claim 1 , wherein the substrate is connected to the negative terminal of the power supply and the counter electrode is connected to the positive terminal of the power supply.
6. The method of claim 1 , wherein, via the EPD process, the radioluminescent phosphor and radioisotope particles bond to the substrate without any additional binder material.
7. The method of claim 1 , further comprising:
coating a surface of the substrate with a photoresist material;
applying a pattern defining a cell to the coated surface using a photolithography process and
applying, via the EPD process, the layer of radioluminescent phosphor with radioisotope particles homogeneously dispersed within the phosphor layer to the substrate to only the patterned area(s) of the substrate.
8. The method of claim 1 , further comprising:
mixing or agitation the electrolyte solution to suspend the radioluminescent phosphor and radioisotope particles therein.
9. The method of claim 1 , wherein the radioluminescent phosphor particles in the electrolyte solution range in size from about 100 nm to 20 microns in diameter.
10. The method of claim 1 , wherein the radioisotope particles in the electrolyte solution range in size from about from 10 nm to 1 micron in diameter.
11. The method of claim 1 , wherein the concentrations of the radioluminescent phosphor particles and the radioisotope particles in the EPD solution are about 75 and 25 wt/wt % based on solid contents, respectively.
12. The method of claim 1 , wherein the thickness of the composite layer formed on the substrate by the EPD process is between about 10 microns to 150 microns.
13. The method of claim 1 , wherein the packaging density range of the composite layer produced by the EPD process is between about 1.8 to 2.1 g/cm 3 .
14. The method of claim 1 , wherein the surface uniformity of the composite layer produced by the EPD process is about ±10 microns.
15. The method of claim 1 , wherein the composite layer produced by the EPD process is substantially planar and provides an optical power output of approximately 50 nW/cm 2 .
16. The method of claim 1 , wherein the substrate comprises a semiconductor configured to absorb beta particles and/or photons and outputting electrical energy.
17. The method of claim 1 , wherein the composite layer is configured as a betavoltaic or beta-photovoltaic cell having a thicknesses range between about 25 to 100 microns, including the substrate layer thickness.
18. The method of claim 1 , wherein the conductive substrate comprises of graphene or indium tin oxide (ITO) on quartz, glass, or sapphire with thicknesses between 0.3 to 1 nm and 100 to 200 nm, respectively.
19. The method of claim 1 , further comprising: separately adding the radioluminescent phosphor particles and the radioisotope particles to the electrolyte solution.