Two-junction photovoltaic devices
The present disclosure relates to a photovoltaic (PV) device that includes a first junction constructed with a first alloy and having a bandgap between about 1.0 eV and about 1.5 eV, and a second junction constructed with a second alloy and having a bandgap between about 0.9 eV and about 1.3 eV, where the first alloy includes III-V elements, the second alloy includes III-V elements, and the PV device is configured to operate in a thermophotovoltaic system having an operating temperature between about 1500° C. and about 3000° C.
1. A photovoltaic (PV) device for a thermophotovoltaic system, the PV device comprising:
a light absorbing stack configured to absorb radiant heat emitted from an emitter operating at a temperature between about 1500° C. and 3000° C.; wherein:
the light absorbing stack consists of:
a first junction constructed with a first alloy having a bandgap between about 1.1 eV and about 1.5 eV;
a second junction constructed with a second alloy having a bandgap between about 0.9 eV and about 1.2 eV;
a tunnel junction positioned between the first junction and the second junction; and
a buffer layer positioned between the first junction and the second junction and comprising between two and 15 individual layers and having a final layer that is lattice-matched to the first junction, wherein:
the first alloy comprises Al x Ga y In 1-x-y As, where 0.05≤x≤0.25 and 0.45<y≤0.65,
the second alloy comprises Ga w In 1-w As, where 0.60<w≤0.80, and
each individual layer in the buffer layer comprises Ga a In 1-a P, where 0.20≤a≤0.51.
2. The PV device of claim 1 , wherein the second alloy comprises about Ga 0.7 In 0.3 As.
3. The PV device of claim 1 , wherein the tunnel junction comprises at least two of gallium, indium, arsenide, or antimony.
4. The PV device of claim 1 , further comprising a substrate, wherein at least one of the substrate or the buffer layer is configured to be removed from the PV device.
5. A thermophotovoltaic system comprising:
an emitter operating at a temperature between about 1900° C. and about 2400° C.; and
a photovoltaic (PV) device, wherein:
the PV device is configured to receive radiant heat from the emitter, and
the PV device comprises:
a light absorbing stack configured to absorb radiant heat emitted from an emitter operating at a temperature between about 1500° C. and 3000° C.; wherein:
the light absorbing stack consists of:
a first junction comprising a first alloy having a bandgap between about 1.1 eV and about 1.5 eV;
a second junction comprising a second alloy having a bandgap between about 0.9 eV and about 1.2 eV,
a tunnel junction, and
a buffer layer comprising between two and 15 individual layers and having a final layer that is lattice matched to the first junction; wherein:
the first alloy comprises Al x Ga y In 1-x-y As z , where 0.05≤x≤0.25 and 0.45<y≤0.65,
the second alloy comprises Ga w In 1-w As, where 0.60<w≤0.80, and
the individual layers in the buffer layer comprise Ga x In 1-x P where 0.20≤x≤0.51.
6. A method comprising:
operating an emitter at a temperature between about 1900° C. and about 2400° C. to create radiant energy;
transferring at least a portion of the radiant energy to a photovoltaic (PV) device; and
converting at least a portion of the transferred radiant energy to electricity, wherein:
the PV device comprises:
a light absorbing stack configured to absorb radiant heat emitted from an emitter operating at a temperature between about 1500° C. and 3000° C.; wherein:
the light absorbing stack consists of:
a first junction comprising a first alloy having a bandgap between about 1.1 eV and about 1.5 eV;
a second junction comprising a second alloy having a bandgap between about 0.9 eV and about 1.2 eV,
a tunnel junction,
a buffer layer comprising between two and 15 individual layers and having a final layer that is lattice matched to the first junction; wherein:
the first alloy comprises Al x Ga y In 1-x-y As z P 1-z , where 0.05≤x≤0.25, 0.45<y≤0.65,
the second alloy comprises Ga w In 1-w As, where 0.60<w≤0.80, and
the individual layers in the buffer layer comprise Ga x In 1-x P where 0.20≤x≤0.51.