Doped perovskite having improved stability, and solar cells made thereof

1. A light-harvesting material, comprising: a perovskite absorber doped with a metal chalcogenide, wherein

the perovskite absorber has the formula ABX 3 ,

A is selected from the group consisting of methyl ammonium, formamidinium and mixtures thereof,

B is lead,

X is I, and

the metal of the metal chalcogenide is lead,

the chalcogenide of the metal chalcogenide is selected from the group consisting of S, Se and mixtures thereof, and

the metal chalcogenide is present in an amount of 5 to 10 percent by weight.

2. The light-harvesting material of claim 1 , wherein

A is methyl ammonium,

and

the chalcogenide of the metal chalcogenide is Se.

3. A photovoltaic device, comprising:

(1) a first conductive layer,

(2) optionally an electron blocking layer, on the first conductive layer,

(3) a semiconductor layer, on the first conductive layer,

(4) a light-harvesting material, on the semiconductor layer,

(5) a hole transport material, on the light-harvesting material, and

(6) a second conductive layer, on the hole transport material,

wherein the light-harvesting material comprises a perovskite absorber doped with a metal chalcogenide,

the perovskite absorber has the formula ABX 3 ,

A is selected from the group consisting of methyl ammonium, formamidinium and mixtures thereof,

B is lead,

X is I, and

the metal of the metal chalcogenide is lead,

the chalcogenide of the metal chalcogenide is selected from the group consisting of S, Se and mixtures thereof, and

the metal chalcogenide is present in an amount of 5 to 10 percent by weight.

4. The photovoltaic device of claim 3 , wherein

A is methyl ammonium,

and

the chalcogenide of the metal chalcogenide is Se.

5. The photovoltaic device of claim of claim 3 , further comprising the electron blocking layer.

6. The photovoltaic device of claim 3 , wherein the first conductive layer is transparent.

7. The photovoltaic device of claim 6 , wherein the first conductive layer comprises at least one transparent conductor selected from the group consisting of indium-tin oxide, fluorinated tin oxide and aluminum-zinc oxide.

8. A method of making the light-harvesting material of claim 1 , comprising:

forming a solution comprising:

a first component selected from the group consisting of methyl ammonium, formamidinium and mixtures thereof,

a second component of lead,

a third component of I, and

a fourth component selected from the group consisting of S, Se, and mixtures thereof, and

forming the light-harvesting material from the solution.

9. The method of claim 8 , further comprising depositing the light-harvesting material on a semiconductor layer by spin-coating.

10. A method of forming the photovoltaic device of claim 3 , comprising:

forming the first conductive layer, and optionally the blocking layer on the first conductive layer;

forming the semiconductor layer, on the first conductive layer;

applying the light-harvesting material, onto the semiconductor layer;

forming the hole transport layer, on the semiconductor layer; and

forming the second conductive layer, on the hole transport layer.

11. The method of claim 10 , wherein forming the semiconductor layer comprises a solvothermal method.

12. The method of claim 10 , wherein forming the second conductive layer comprises sputtering or evaporation.

13. The method of claim 10 , wherein applying the light-harvesting material comprises spin coating.