Methods for perovskite device processing by vapor transport deposition
Structures and methods for manufacturing photovoltaic devices by forming perovskite layers and perovskite precursor layers using vapor transport deposition (VTD) are described.
1. A method of forming a perovskite precursor layer comprising:
providing a substrate stack in a deposition chamber, the substrate stack having a first charge transport layer on an electrode;
depositing a first perovskite-forming composition on the substrate stack in the deposition chamber by a vapor transport deposition (VTD) process, comprising:
heating a source material to a temperature in a range of 375° C. to 550° C., wherein the source material comprises at least one of: lead iodide (PbI 2 ), lead bromide (PbBr 2 ), cesium bromide (CsBr), cesium lead iodide (CsPbI 3 ), cesium tin iodide (CsSnI 3 ), lead chloride (PbCl 2 ), tin iodide (SnI 2 ), tin bromide (SnBr 2 ), or tin chloride (SnCl 2 );
providing a vapor curtain to direct vapor of the source material using a carrier gas toward the substrate stack in the deposition chamber, wherein the vapor curtain has a width greater than 1 meter, the deposition chamber having a pressure in a range of 0.1 to 2.0 Torr; and
forming the precursor layer, at a deposition rate in a range of 0.01 to 1.50 μm per minute, to a thickness of 100-2000 nm, wherein the precursor layer comprises a plurality of metal halide crystal grain structures, wherein: the grain structures have a height, normal to the surface of the substrate stack, and a width, parallel to the surface of the substrate stack, and an average grain width is less than a third of an average grain height.
2. The method of claim 1 , wherein:
the deposition chamber has a pressure in a range of 0.1 to 1.0 Torr;
the deposition chamber has a temperature in a range of 20° C. to 150° C.;
the source material is heated to a temperature in a range of 400° C. to 525° C.; and
a carrier gas flow rate in a range from 80 sccm to 150 sccm.
3. The method of claim 1 , wherein the source material is provided as a powder.
4. The method of claim 1 , wherein the precursor layer comprises at least one metal halide in a crystal matrix having a porosity in a range from 35% to 65%.
5. The method of claim 1 , wherein forming the precursor layer to the thickness comprises forming the precursor layer to a thickness in a range of 200-1500 nm.
6. The method of claim 1 , wherein the precursor layer comprises at least one of: lead iodide (PbI 2 ), lead bromide (PbBr 2 ), cesium bromide (CsBr), or cesium tin iodide (CsSnI 3 ), in a crystal matrix having a porosity greater than 35%.
7. The method of claim 1 , wherein the precursor layer comprises a plurality of lead iodide crystal grain structures, wherein: the grain structures have a height, normal to the surface of the substrate stack, and a width, parallel to the surface of the substrate stack, and at least a quarter of grain structures of the precursor layer have a height that is in a range of 200 nm to 700 nm and a width that is less than 100 nm.
8. The method of claim 1 , wherein the deposition rate is in a range of 0.05 to 0.50 μm per minute.
9. The method of claim 1 , wherein the carrier gas comprises at least one of: argon, helium, or nitrogen.
10. The method of claim 1 , wherein the precursor layer comprises a plurality of crystalline grains, and wherein 30-100% of the grains have a size with at least one dimension having a length in a range of 200-800 nm.
11. A method of forming a perovskite precursor layer for a photovoltaic device, the method comprising:
providing a substrate stack in a deposition chamber, the substrate stack having a first charge transport layer on an electrode;
depositing a first perovskite-forming composition on the substrate stack in the deposition chamber by a vapor transport deposition (VTD) process, comprising:
heating a source material to a temperature in a range of 400° C. to 525° C.;
providing a vapor curtain to direct vapor of the source material using a carrier gas toward the substrate stack in the deposition chamber, wherein:
the deposition chamber has a pressure in a range of 0.1 to 1.0 Torr;
the deposition chamber has a temperature in a range of 20° C. to 150° C.;
the source material comprises at least one of: lead iodide (PbI 2 ), lead bromide (PbBr 2 ), cesium bromide (CsBr), cesium lead iodide (CsPbI 3 ), cesium tin iodide (CsSnI 3 ), lead chloride (PbCl 2 ), tin iodide (SnI 2 ), tin bromide (SnBr 2 ), or tin chloride (SnCl 2 );
a carrier gas flow rate is in a range from 80 sccm to 150 sccm; and
forming the precursor layer to a thickness in a range of 200 nm to 1500 nm,
whereby the precursor layer comprises a plurality of metal halide crystal grain structures.
12. The method of claim 11 , wherein the metal halide grain structures have a height, normal to the surface of the substrate stack, and a width, parallel to the surface of the substrate stack, and at least a quarter of grain structures of the precursor layer have a height that is in a range of 200 nm to 700 nm, and a width that is less than 100 nm.