2-terminal metal halide semiconductor/C-silicon multijunction solar cell with tunnel junction
A 2-terminal multi-junction solar cell having a thin film of metal halide semiconductor as the top solar-cell material and crystalline silicon as the bottom solar-cell material. In the illustrative embodiment, the top solar-cell material is a perovskite of the form AM(I x H 1-x ) 3 , where A is a cation, preferably methylammonium (CH 3 NH 3 ), formamidinium ([R 2 N—CH═NR 2 ] + ), or cesium; M is metal, preferably Pb, Sn, Ge; H is a halide, preferably Br or Cl; and x=iodine fraction, in the range of 0 to 1, inclusive. The integration of the two solar-cell materials is enabled by the use of a tunnel junction composed of indirect band-gap material.
1. An article comprising a two-terminal multi-junction solar cell comprising:
a crystalline n-type or p-type silicon sub-cell, a top layer of which is a p++ single-crystalline silicon emitter or an n++ single-crystalline silicon emitter, respectively;
a bottom electrode disposed below a bottom surface of the crystal silicon sub-cell;
a tunnel junction disposed above the silicon sub-cell, wherein the tunnel junction consists essentially of one of either degenerately doped n-type polysilicon or degenerately doped p-type polysilicon, respectively;
a metal halide semiconductor sub-cell disposed above the tunnel junction; and
a top electrode disposed above a top surface of the metal halide semiconductor sub-cell.
2. The article of claim 1 wherein the metal halide semiconductor is defined by the formula AM(I x H 1-x ) 3 , where A is a cation, M is a metal, H is a halide, and x, which is iodine fraction, falls in a range of 0 to 1, inclusive.
3. The article of claim 1 wherein the metal halide semiconductor is a metal halide perovskite.
4. The article of claim 1 wherein the crystalline silicon sub-cell comprises, below the silicon emitter, a silicon base, and a back surface field disposed proximal to a bottom surface of the silicon base.
5. The article of claim 1 wherein the metal halide semiconductor sub-cell comprises:
a transport layer, wherein the transport layer is an electron transport layer when a silicon base in the crystalline silicon sub-cell is n-type silicon and wherein the transport layer is a hole transport layer when the silicon base in the crystalline silicon sub-cell is p-type silicon;
a layer of metal halide semiconductor; and
a heterojunction contact, wherein the heterojunction contact is p-type when the silicon base is n-type silicon and the heterojunction contact is n-type when the silicon base is p-type silicon.
6. The article of claim 5 wherein the transport layer comprises TiO 2 .
7. The article of claim 5 wherein the metal halide semiconductor is a metal halide perovskite.
8. The article of claim 5 wherein the heterojunction contact comprises spiro-OMeTAD.
9. The article of claim 1 wherein the top electrode comprises a mesh of silver nanowires.
10. An article comprising a two-terminal multi-junction solar cell comprising:
a bottom sub-cell comprising a single-crystalline silicon base and a single-crystalline silicon emitter;
a tunnel junction disposed above the bottom sub-cell, wherein the tunnel junction consists essentially of one of either degenerately doped n-type polysilicon or degenerately doped p-type polysilicon; and
a top sub-cell disposed above the tunnel junction, wherein the top sub-cell comprises a metal halide perovskite.
11. The article of claim 10 further comprising a mesh of silver nanowires disposed above the top sub-cell and serving as a top electrical contact of the solar cell.
12. The article of claim 10 wherein:
the bottom sub-cell further comprises a n++ back surface field; and
the top sub-cell further comprises an electron transport layer and an organic p-type heterojunction contact.
13. A method for forming a two-terminal multi-junction solar cell comprising:
forming a single-crystalline silicon sub-cell comprising a single-crystalline silicon emitter;
forming a tunnel junction above the single crystalline silicon sub-cell, wherein the tunnel junction consists essentially of one of either degenerately doped n-type polysilicon or degenerately doped p-type polysilicon; and
forming a metal halide semiconductor sub-cell above the tunnel junction.
14. The method of claim 13 and further comprising forming a top electrical contact by depositing a mesh of silver nanowires above the metal halide semiconductor sub-cell.
15. The method of claim 13 wherein forming the metal halide semiconductor sub-cell further comprises:
forming a transport layer above the tunnel junction, wherein the transport layer is an electron transport layer when a silicon base in the single-crystalline silicon sub-cell is n-type silicon and wherein the transport layer is a hole transport layer when the silicon base in the single-crystalline silicon sub-cell is p-type silicon;
depositing metal halide semiconductor above the transport layer; and
depositing a heterojunction contact above the metal halide semiconductor, wherein the heterojunction contact is p-type when the silicon base is n-type silicon and the heterojunction contact is n-type when the silicon base is p-type silicon.
16. The method of claim 13 wherein the metal halide semiconductor is defined by the formula APb(I x H 1-x ) 3 , where A is a cation, H is a halide, and x, which is iodine fraction, falls in a range of 0 to 1, inclusive.
17. The method of claim 13 wherein forming the tunnel junction further comprises: at least partially recrystallizing one of degenerately doped n-type amorphous silicon or degeneratively doped p-type amorphous silicon.
18. The method of claim 13 wherein the metal halide semiconductor is methylammonium lead iodide perovskite.