CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 35 U.S.C. § 371 U.S. National Stage of International Application No. PCT/GB2018/050741, filed on Mar. 21, 2018, which claims priority to Great Britain Patent Application No. 1704738.2, filed Mar. 24, 2017, the entire content of each of which is incorporated herein by reference.

The present invention relates to an improved optoelectronic device and more specifically a solar photovoltaic cell. The optoelectronic device may have a reflective face. The optoelectronic device may generate and store electrical energy.

The efficiency with which renewable energy can be harnessed and converted to electrical energy is an ongoing challenge for the energy industry. The demand for sources of renewable energy has driven significant improvements in the cost and efficiency of solar photovoltaic cells but existing technology still represents a relatively expensive method of generating electricity. Also, existing solar photovoltaic cells are relatively inefficient compared to other methods of generating electricity.

The renewable energy sector is becoming increasingly diverse and the need for energy storage is becoming increasingly important. The responsiveness of renewable energy sources to peak demand is limited but this may be at least partially mitigated if the electricity produced can be stored for release and used when demand is high.

The present invention aims to help increase the efficiency of optoelectronic devices and may address the energy storage challenges faced by the renewable energy sector.

In accordance with a first aspect of the present invention there is provided an optoelectronic device comprising:a substrate having a first and a second substantially planar face;a series of grooves in the first substantially planar face; anda first and a second electrical conductor on the second substantially planar face;wherein a first face of the first and second electrical conductors is reflective.

The first faces of the first and second electrical conductors may comprise a mirror. The first faces of the first and second electrical conductors may be reflective of light and/or capable of reflecting light and/or reflect light. The first faces of the first and second electrical conductors may be substantially reflective of light and/or substantially capable of reflecting light.

Each groove of the series of grooves typically has a first and a second face. The first face of the groove is normally coated with a semiconductor material and the second face of the groove is normally coated with a conductor material. The semiconductor material and the conductor material are normally in contact with another semiconductor material in the groove.

In use, the optoelectronic device is exposed to light. The light typically comprises one or more of ultraviolet, infrared, visible. Electrical energy, electricity, normally direct electrical current, is typically generated when the semiconductor and another semiconductor materials are, and normally a junction between the semiconductor and another semiconductors is, exposed to the light.

The inventor of the present invention has appreciated that not all light, typically incident light, that reaches the series of grooves in the first substantially planar face and typically the semiconductor and another semiconductor materials, normally the junction between the semiconductor and another semiconductors, is typically absorbed and some of this light passes into the surrounding substrate.

It may be an advantage of the present invention that the first and second electrical conductors on the second substantially planar face of the substrate can reflect at least some, typically most, of the light that has passed into the surrounding substrate back through the semiconductor and another semiconductor materials, and typically a junction between the semiconductor and another semiconductors, so as to generate more electrical energy, electricity, normally direct electrical current.

The reflection of at least some, typically most, of the light that has passed into the surrounding substrate back through the semiconductor and another semiconductor materials, and typically a junction between the semiconductor and another semiconductors, is greater when the first faces of the first and second electrical conductors are reflective and/or comprise a mirror.

The reflection of at least some, typically most, of the light that has passed into the surrounding substrate back through the semiconductor and another semiconductor materials, and typically a junction between the semiconductor and another semiconductors, normally wants to be with a minimum of further re-reflections and/or as quickly as possible. The reflective and/or mirrored surface of the first faces of the first and second electrical conductors may therefore be one or more of irregular, regular, zig zag and saw-tooth in shape. This may have the advantage that the light that has passed into the surrounding substrate is reflected back at a plurality of different angles, with a minimum of further re-reflections and/or as quickly as possible.

The optoelectronic device may further comprise a first outer electrical conductor spaced from the first and second electrical conductors by a capacitor or supercapacitor material.

In certain embodiments the optoelectronic device comprises a substrate having a first and a second substantially planar face; a series of grooves in the first substantially planar face; and a first and a second electrical conductor on the second substantially planar face; wherein a first face of the first electrical conductor and a first face of the second electrical conductor are reflective and wherein the optoelectronic device further comprises a first outer electrical conductor spaced from the first and second electrical conductors by a layer of capacitor material or supercapacitor material.

In certain embodiments the optoelectronic device comprises a substrate having a first and a second substantially planar face; a series of grooves in the first substantially planar face; and a first and a second electrical conductor on the second substantially planar face; wherein a first face of the first electrical conductor and a first face of the second electrical conductor reflect light; wherein each groove of the series of grooves has a first and a second face, the first face of the groove is coated with a semiconductor material and the second face of the groove is coated with a conductor material, the semiconductor material and the conductor material are in contact with another semiconductor material in the groove and wherein the optoelectronic device further comprises a first outer electrical conductor spaced from the first and second electrical conductors by a layer of capacitor material.

The capacitor material may have characteristics of a supercapacitor. The optoelectronic device normally comprises a supercapacitor material. The capacitor or supercapacitor material may be and/or may be referred to as a dielectric and/or insulator material. The insulator material is typically an electrical insulator material.

The capacitor or supercapacitor material is typically a layer of material. The capacitor or supercapacitor material is typically a high dielectric material. The capacitor or supercapacitor material may be an adhesive material and/or a layer of adhesive.

The capacitor or supercapacitor layer is typically from 20 to 2000 nm thick, usually from 50 to 500 nm thick.

The first and second electrical conductors typically have first and second faces. The first faces of the first and second electrical conductors normally face and/or are in contact with the substrate, the second faces of the first and second electrical conductors normally face and/or are in contact with the capacitor or supercapacitor material.

The first and second electrical conductors on the second substantially planar face are typically electrically insulated from one another. The first and second electrical conductors are typically not in electrical contact with one another. There is normally a gap between the first and second electrical conductors. The capacitor or supercapacitor material may be between the first and second electrical conductors.

The first and second electrical conductors are typically made of metal. The first outer electrical conductor is typically made of metal. The first and second electrical conductors may comprise one or more of aluminium, copper, silver, zinc, lead, antimony, gold, nickel, bismuth, and indium. The first outer electrical conductor may comprise one or more of aluminium, copper, silver, zinc, lead, antimony, gold, nickel, bismuth, and indium.

The first and second electrical conductors on the second substantially planar face are typically busbars. The first electrical conductor may be and/or may be referred to as a first busbar. The second electrical conductor may be and/or may be referred to as a second busbar.

The first and second electrical conductors may provide and/or be part of the positive and negative poles of an electrical circuit.

In use, the capacitor or supercapacitor material typically draws electrical energy from the electrical circuit, stores and then releases the electrical energy. The capacitor or supercapacitor material may store electrical energy using static double-layer capacitance and/or electrochemical pseudocapacitance.

It may be an advantage of the present invention that in use, the first and second electrical conductors are used to collect from and/or convey an electrical charge along a length of the optoelectronic device, these electrical conductors having a lower electrical resistance compared to the first substantially planar face and/or the series of grooves. This typically means that the length of the optoelectronic device and hence the number of grooves and/or number of series of grooves can be increased without an otherwise corresponding decrease in the electrical charge that can be collected.

The series of grooves may include a first outermost groove and a second outermost groove. There may be a first and a second hole in the substrate. The first hole may provide electrical communication between the first outermost groove and the second substantially planar face of the substrate and the second hole may provide separate electrical communication between the second outermost groove and the second substantially planar face of the substrate.

In use, the first and second holes are typically used to carry electrical charge between the first and the second substantially planar faces of the substrate, and typically from the first to the second substantially planar face of the substrate.

The first and second holes typically each have a side or sides. The side or sides may be referred to as an internal surface/internal surfaces. The side or sides of the first and second holes typically comprise the substrate. The side or sides of the first and second holes, and therefore the substrate that the side or sides comprise, may provide the electrical communication. The first and second holes may be empty and/or hollow.

The first hole typically passes through the first substantially planar face of the substrate proximate to the first outermost groove and through the first electrical conductor on the second substantially planar face of the substrate. The second hole typically passes through the first substantially planar face of the substrate proximate to the second outermost groove and through the second electrical conductor on the second substantially planar face of the substrate.

The first and second holes may be two of a plurality of holes. The plurality of holes may comprise a first group of holes including the first hole and a second group of holes including the second hole. The holes of the first group of holes may all pass through and/or be in electrical communication with the first electrical conductor. The holes of the second group of holes may all pass through and/or be in electrical communication with the second electrical conductor.

The first and second holes may have a diameter of from 5 to 2000 microns, typically from 100 to 500 microns. There may be at least one hole for every from 3 to 10 cm2of the substrate, typically at least one hole for every 5 cm2of the substrate. There may be at least one hole for every from 3 to 10 cm2of substrate length, typically at least one hole for every 5 cm2of substrate length.

The side or sides of the first and second holes are normally coated with the conductor material and/or the semiconductor material. The aspect ratio of the depth to the width of the first and second holes is typically such that the conductor material and/or the semiconductor material coats enough of the side or sides of the first and second holes to establish the electrical communication between the first and second outermost grooves and the second substantially planar face of the substrate. The first and second holes may be at least partially filled with a filler material to increase the reliability and/or effectiveness of the electrical communication between the first and second outermost grooves and the second substantially planar face of the substrate.

The series of grooves may comprise a first and a second series of grooves. The substrate may further comprise a channel between the first and second series of grooves.

It may be an advantage of the present invention that the capacitor or supercapacitor material aids operation of the optoelectronic device by providing electrical energy when energy demand spikes, such as a surge when devices connected to the optoelectronic device are turned on.

The capacitor or supercapacitor material typically provides the function of a supercapacitor, also referred to as an ultracapacitor. The function of the capacitor or supercapacitor may be provided by the capacitor or supercapacitor material alone or may require the interaction of the capacitor or supercapacitor material with one or more of the semiconductor material, conductor material and another semiconductor material.

The optoelectronic device typically further comprises a protective layer on the first outer electrical conductor. The first outer electrical conductor typically has a first and a second substantially planar face. The capacitor or supercapacitor material is typically in contact and/or on the first substantially planar face. The protective layer is typically in contact and/or on the second substantially planar face.

The protective layer may be and/or may provide one or more of physical protection, environmental protection, a gas barrier and electrical insulation.

The optoelectronic device may be in electrical communication with a load. The load is typically an electrical component that consumes electrical energy. The load may for example be a light bulb.

In use, the capacitor or supercapacitor material typically stores electrical energy that the load does not consume. In this way, excess electrical energy can be stored for future use by the load. There is therefore electrical energy available to the load when the optoelectronic device is not generating sufficient electrical energy.

It may be an advantage of the present invention that the optoelectronic device generates and stores electrical energy.

The first face of the groove may be longer than the second face of the groove or the second face of the groove may be longer than the first face of the groove. When the first face of the groove is longer than the second face of the groove the first face is typically at least 1000 nm long and the second face is typically at least 300 nm long. When the second face of the groove is longer than the first face of the groove the second face is typically at least 1000 nm long and the first face is typically at least 300 nm long.

When the first face of the groove is longer than the second face of the groove or the second face of the groove is longer than the first face of the groove, the groove typically has an asymmetric shape.

The length of the first face of the groove is normally measured from a junction between the first face of the groove and the first surface of the substrate and a junction between the first and second faces of the groove. The length of the second face of the groove is normally measured from a junction between the second face of the groove and the second surface of the substrate and a junction between the second and first faces of the groove.

Preferably the first face of the groove is longer than the second face of the groove. The first face of the groove is typically at least twice the length of the second face of the groove.

At the second side of the groove there is typically a gap between the semiconductor material on the second side of the groove and the another semiconductor material in the groove.

It may be an advantage of the present invention that, in use, the gap between the semiconductor material on the second side of the groove and the another semiconductor material in the groove one or more of stops, mitigates and substantially reduces the occurrence of shunting across the groove and therefore typically between the first and second sides of the groove.

The gap is typically an air gap. The gap may be filled with another material, preferably a non-conducting and/or electrically insulative material. The gap is typically a form of electrical insulation between the semiconductor material on the second side of the groove and the another semiconductor material in the groove.

The gap between the semiconductor material and the another semiconductor material at the second side of the groove, typically means that the another semiconductor material is not in contact, and/or is insulated from, the semiconductor material.

The gap between the semiconductor material on the second side of the groove and the another semiconductor material in the groove may be at least 1 nm in length, normally at least 20 nm in length and typically at least 100 nm in length.

It may be an advantage of the present invention that the gap makes the optoelectronic device less susceptible, typically resistant, to shorting and/or shunting across the groove. The gap in between the semiconductor and the another semiconductor material is designed to mitigate a charge transfer path/route from the semiconductor material on one side of the groove, through the another semiconductor and into the semiconductor material on the opposite side of the groove. This typically makes the optoelectronic device less susceptible to shunting. Shunting is a parasitic parallel resistance across the optoelectronic device. Maximising shunt resistance makes the optoelectronic device more efficient.

The first face of the groove is normally at a first angle relative to a normal from the substrate and the second face of the groove is normally at a second angle relative to the normal from the substrate. The first angle is normally from 45 to less than or equal to 90°. The second angle is normally from 45 to less than or equal to 90°.

The conductor material is normally one or more of on, in contact with and coated on the second face of the groove and second surface of the substrate adjacent the groove. The conductor material may further be one or more of on, in contact with and coated on the first surface of the substrate adjacent the groove.

The semiconductor material is normally one or more of on, in contact with and coated on the first face of the groove and first surface of the substrate adjacent the groove. The semiconductor material may further be one or more of on, in contact with and coated on the second surface of the substrate adjacent the groove.

The another semiconductor typically at least partially fills the groove and/or fills the groove between the first and second faces of the groove.

The another semiconductor in the groove may be referred to as having a surface between the first and second faces of the groove. The surface of the another semiconductor is typically not parallel and normally not substantially parallel to the plane of the substrate. The surface of the another semiconductor is typically at an angle and/or tilted with respect to the plane of the substrate.

The surface of the another semiconductor may be inclined or declined relative to a normal from the substrate. The surface of the another semiconductor may be non-normal to a normal from the substrate. When the surface of the another semiconductor is one or more of inclined or declined and non-normal relative to a normal from the substrate, the surface of the another semiconductor may be referred to as tilted relative to the groove.

The first surface of the another semiconductor may be parallel at least in part to the first face of the groove and the second surface of the another semiconductor may be parallel at least in part to the second face of the groove.

There may be an aperture in the another semiconductor material. The aperture may be referred to as a gap and/or crack. The shape of the aperture is typically substantially conformal with the shape of the groove. The shape of the aperture may match the shape of the groove.

The first and second surfaces of the another semiconductor may be referred to as sides of the aperture. The sides of the aperture may be substantially parallel to the first and second faces of the groove respectively. The sides of the aperture may be steeper or shallower than the first and/or second faces of the groove but are still considered substantially parallel.

The first and the second face of the groove typically define a cavity of the groove therebetween. The aperture normally extends down into the cavity. The aperture typically extends down into the cavity between the first and second face of the groove.

The another semiconductor material may occupy from 15 to 75%, optionally from 20 to 50% of the volume of the cavity of the groove. When for example the another semiconductor material occupies from 20 to 50% of the volume of the cavity, a remaining 70 to 40% corresponds to the aperture in the another semiconductor material. The conductor material and semiconductor material account for the remaining volume. The volume of the cavity occupied by the another semiconductor material may be related to the shape of the groove.

The aperture in the another semiconductor material may extend up to 90%, optionally from 20 to 80% and typically from 50 to 80% of the distance into the cavity of the groove. It may be an advantage of the present invention that an aperture in the semiconductor material that extends about 50% of the distance into the cavity from the top of the cavity may increase the electrical current generated by the optoelectronic device. The distance the aperture in the semiconductor material extends into the cavity from the top of the cavity may be related to the shape of the groove.

The semiconductor material may coat and/or cover from 20 to 80%, normally from 40 to 60% and typically about 50% of the first face of the groove. The semiconductor material may coat and/or cover about 75% of the first face of the groove. The conductor material may coat and/or cover from 20 to 80%, normally from 40 to 60% and typically about 50% of the second face of the groove. The conductor material may coat and/or cover about 75% of the second face of the groove.

It may be an advantage of the present invention that when the semiconductor material and/or conductor material coats and/or covers about 50%, preferably about 75%, of the first face and/or second face of the groove respectively, one or more of the efficiency, electrical current generated, power output and photoelectric conversion efficiency of the optoelectronic device is increased.

The another semiconductor in the groove may be, and/or may be referred to as, coated on the first and second face of the groove. The coat of the another semiconductor material may be from 50 nm to 1000 nm thick, normally from 100 nm to 500 nm thick and typically from 100 nm to 200 nm thick. The coat of the another semiconductor material may therefore be referred to as a relatively thin coating.

The optoelectronic device is typically a solar photovoltaic cell.

