Photoelectric conversion element and method for manufacturing the same

1. A photoelectric conversion element, comprising:

a first conductive layer;

a second conductive layer; and

a photoelectric conversion layer located between the first conductive layer and the second conductive layer,

the photoelectric conversion layer including Sn and Pb,

the photoelectric conversion layer including

a first partial region,

a second partial region between the first partial region and the second conductive layer, and

a third partial region between the second partial region and the second conductive layer,

the first partial region including a first Sn concentration and a first Pb concentration,

the second partial region including at least one of a second Sn concentration or a second Pb concentration,

the second Sn concentration being less than the first Sn concentration,

the second Pb concentration being greater than the first Pb concentration,

the third partial region including Sn, oxygen, and Pb.

2. The element according to claim 1 , wherein

the third partial region includes a bond of Sn and oxygen.

3. The element according to claim 1 , wherein

the third partial region includes a bond of Pb and iodine.

4. The element according to claim 1 , wherein

the photoelectric conversion layer includes a plurality of crystal grains.

5. The element according to claim 4 , wherein

one of the plurality of crystal grains has a perovskite structure.

6. The element according to claim 1 , wherein

a ratio of a Sn concentration to a Pb concentration in at least a portion of the first partial region is not less than 1.2 times an average composition ratio of an average Sn concentration in the photoelectric conversion layer to an average Pb concentration in the photoelectric conversion layer.

7. The element according to claim 1 , wherein

a ratio of a Sn concentration to a Pb concentration in at least a portion of the second partial region is not more than 0.8 times an average composition ratio of an average Sn concentration in the photoelectric conversion layer to an average Pb concentration in the photoelectric conversion layer.

8. The element according to claim 1 , wherein

the photoelectric conversion layer further includes a fourth partial region between the first partial region and the second partial region,

a change rate of a Sn concentration with respect to a positional change in a first direction in the fourth partial region is less than a change rate of a Sn concentration with respect to a positional change in the first direction in the first partial region,

the first direction is from the first conductive layer toward the second conductive layer, and

the change rate of the Sn concentration with respect to the positional change in the first direction in the fourth partial region is less than a change rate of a Sn concentration with respect to a positional change in the first direction in the second partial region.

9. The element according to claim 1 , wherein

the first partial region does not include oxygen, or an oxygen concentration in the first partial region is not more than 1/100 of an oxygen concentration in the third partial region, and

the second partial region does not include oxygen, or an oxygen concentration in the second partial region is not more than 1/100 of the oxygen concentration in the third partial region.

10. The element according to claim 1 , wherein

a thickness of the third partial region along a first direction is not less than 0.1% and not more than 5% of a thickness of the photoelectric conversion layer along the first direction, and

the first direction is from the first conductive layer toward the second conductive layer.

11. The element according to claim 1 , wherein

a thickness of the third partial region along a first direction is not less than 1 nm and not more than 20 nm, and

the first direction is from the first conductive layer toward the second conductive layer.

12. The element according to claim 1 , wherein

a thickness of the third partial region along a first direction is less than a thickness of the first partial region along the first direction and less than a thickness of the second partial region along the first direction, and

the first direction is from the first conductive layer toward the second conductive layer.

13. The element according to claim 1 , further comprising:

a second conductive layer-side intermediate layer located between the photoelectric conversion layer and the second conductive layer,

the third partial region contacting the second conductive layer-side intermediate layer.

14. The element according to claim 13 , wherein

the second conductive layer-side intermediate layer includes at least one selected from the group consisting of polyaniline, a polyaniline derivative, polythiophene, a polythiophene derivative, polyethylene dioxythiophene:polystyrenesulfonic acid (PEDOT:PSS), polyethyleneimine, a polyethyleneimine derivative, fullerene, a fullerene derivative, titanium oxide, zinc oxide, molybdenum oxide, tungsten oxide, aluminum oxide, copper oxide, vanadium oxide, nickel oxide, lithium oxide, calcium oxide, cesium oxide, copper iodide, copper thiocyanate, lithium fluoride (LiF), and metal calcium.

15. The element according to claim 1 , wherein

the photoelectric conversion layer includes at least one of a compound expressed by A 1 BX 1 3 or a compound expressed by A 2 2 A 1 m−1 B m X 1 3m+1 ,

the A 1 is a monovalent cation including at least one selected from the group consisting of Cs + , Rb + , K + , Na + , R 1 NH 3 + , R 1 2 NH 2 + , and HC(NH 2 ) 2 + ,

the R 1 in the A 1 is at least one monovalent group selected from the group consisting of hydrogen, a linear alkyl group including not less than 1 and not more than 18 carbon atoms, a branched alkyl group including not less than 1 and not more than 18 carbon atoms, a cyclic alkyl group including not less than 1 and not more than 18 carbon atoms, a substituted aryl group, a non-substituted aryl group, a substituted heteroaryl group, and a non-substituted heteroaryl group,

the A 2 is a monovalent cation including at least one selected from the group consisting of R 1 HN 3 + , R 1 2 NH 2 + , C(NH 2 ) 3 + , and R 2 C 2 H 4 NH 3 + ,

the R 2 in the A 2 is at least one monovalent group selected from the group consisting of a substituted aryl group, a non-substituted aryl group, a substituted heteroaryl group, and a non-substituted heteroaryl group,

the B is a divalent cation including at least one selected from the group consisting of Pb 2 + and Sn 2 + ,

the X 1 is at least one monovalent negative ion selected from the group consisting of F − , Cl − , Br − , I − , SCN − , and CH 3 COO − , and

m is an integer not less than 1 and not more than 20.