Method for forming hole transport layer on surface of substrate, hole transport layer, solar cell and preparation method therefor, and photovoltaic module

1. A hole transport layer for a solar cell, comprising:

N consecutive sub-layers, N≥2;

wherein:

each of the sub-layers comprises an inorganic hole transport material;

one of the N sub-layers is a doped sub-layer further comprising a doping material; and

the doped sub-layer is the 1st sub-layer or the N-th sub-layer, and the doping material at least comprises KI.

2. The hole transport layer according to claim 1 , wherein the inorganic hole transport materials of the sub-layers are same as each other.

3. The hole transport layer according to claim 1 , wherein the doping material further comprises one or more of NiO x , CuO, Cu 2 O, CuzS, CuI, CuSCN, CuGaO 2 , MgO, MnO, MnO 2 , Ag, Ag 2 O, Co, CoO, Li, Cs, Pb, In, Ga, Hg, Hg 2 O, Cr 2 O 3 , SnO, SnS, PbO, or Pr 2 O 3 .

4. The hole transport layer according to claim 1 , wherein based on a mass of the doped sub-layer, a total mass percentage content of the doping material in the doped sub-layer is smaller than or equal to 25%.

5. The hole transport layer according to claim 1 , wherein the doped sub-layer of the hole transport layer satisfies at least one of:

a mass percentage content of KI in the doped sub-layer is smaller than or equal to 20%; or

the doped sub-layer comprises MgO and KI, and a mass percentage content of each of MgO and KI in the doped sub-layer is independently smaller than or equal to 20%.

6. The hole transport layer according to claim 1 , wherein:

the N sub-layers have gradient increase or decrease in forbidden band width, and an absolute value of a difference between forbidden band widths of two adjacent ones of the sub-layers, |ΔEg(HTL)|, satisfies: 0 eV<|ΔEg(HTL)|≤1.5 eV; and/or

the N sub-layers have gradient increase or decrease in conduction band bottom energy level, and an absolute value of a difference between conduction band bottom energy levels of two adjacent ones of the sub-layers, |ΔCBM(HTL)|, satisfies: 0 eV<|ΔCBM(HTL)|≤1.5 eV.

7. The hole transport layer according to claim 1 , wherein the hole transport layer has a total thickness of 5 nm to 150 nm.

8. A solar cell, comprising:

a hole transport layer comprising:

N consecutive sub-layers, N≥2;

wherein:

each of the sub-layers comprises an inorganic hole transport material;

one of the N sub-layers is a doped sub-layer further comprising a doping material; and

the doped sub-layer is the 1st sub-layer or the N-th sub-layer, and the doping material at least comprises KI.

9. A photovoltaic module, comprising the solar cell according to claim 8 .

10. The hole transport layer according to claim 1 , wherein the N sub-layers further comprises another doped sub-layer, and the another doped sub-layer of the hole transport layer satisfies at least one of:

the another doped sub-layer comprises one or more of NiO x , CuO, Cu 2 O, Cu 2 S, CuI, CuSCN, CuGaO 2 , Ag, and Ag 2 O, and a mass percentage content of each of the one or more of NiO x , CuO, Cu 2 O, Cu 2 S, CuI, CuSCN, CuGaO 2 , Ag, and Ag 2 O in the another doped sub-layer is independently smaller than or equal to 15%;

the another doped sub-layer comprises one or two of MgO and KI, and a mass percentage content of each of the one or two of MgO and KI in the another doped sub-layer is independently smaller than or equal to 20%;

the another doped sub-layer comprises one or two of MnO and MnO 2 , and a mass percentage content of each of the one or two of MnO and MnO 2 in the another doped sub-layer is independently smaller than or equal to 10%;

the another doped sub-layer comprises one or two of Co and CoO, and a mass percentage content of each of the one or two of Co and CoO in the another doped sub-layer is independently smaller than or equal to 8%; or

the another doped sub-layer comprises one or more of Li, Cs, Pb, In, Ga, Hg, Hg 2 O, Cr 2 O 3 , SnO, SnS, PbO, and Pr 2 O 3 , and a mass percentage content of each of the one or more of Li, Cs, Pb, In, Ga, Hg, Hg 2 O, Cr 2 O 3 , SnO, SnS, PbO, and Pr 2 O 3 , in the another doped sub-layer is independently smaller than or equal to 25%.

11. A method for forming the hole transport layer of claim 1 on a surface of a substrate, comprising:

providing M target materials comprising the inorganic hole transport materials; and

forming the hole transport layer on the surface of the substrate using magnetron sputtering, the hole transport layer at least comprising the N consecutive sub-layers;

wherein M and N are integers, 2≤N≤M, and one of the M target materials is a doped target material further comprising the doping material.

12. The method according to claim 11 , wherein the inorganic hole transport materials of the target materials are same as each other.

13. The method according to claim 11 , wherein the doping material further comprises one or more of NiO x , CuO, Cu 2 O, Cu 2 S, CuI, CuSCN, CuGaO 2 , MgO, MnO, MnO 2 , Ag, Ag 2 O, Co, CoO, Li, Cs, Pb, In, Ga, Hg, Hg 2 O, Cr 2 O 3 , SnO, SnS, PbO, or Pr 2 O 3 .

14. The method according to claim 1 , wherein the doped target material is the 1st target material or the M-th target material.

15. The method according to claim 11 , wherein based on a mass of the doped target material, a total mass percentage content of the doping material in the doped target material is smaller than or equal to 25%.

16. The method according to claim 15 , wherein the doped target material satisfies:

a mass percentage content of KI in the doped target material is smaller than or equal to 20%; or

the doped target material comprises MgO and KI, and a mass percentage content of each of MgO and KI in the doped target material is independently smaller than or equal to 20%.

17. The method according to claim 11 , wherein the hole transport layer has a gradient change in energy level.

18. The method according to claim 17 , wherein:

the hole transport layer has a gradient change in forbidden band width, the M target materials have a gradient change in forbidden band width, and an absolute value of a difference between forbidden band widths of two adjacent ones of the target materials, |ΔEg(TAG)|, satisfies: 0 eV≤|ΔEg(TAG)|≤1.5 eV; and/or

the hole transport layer has a gradient change in conduction band bottom energy level, the M target materials have a gradient change in conduction band bottom energy level, and an absolute value of a difference between conduction band bottom energy levels of two adjacent ones of the target materials, |ΔCBM(TAG)|, satisfies: 0 eV≤|ΔCBM(TAG)|≤1.5 eV.

19. The method according to claim 11 , wherein the substrate comprises a transparent electrode, a metal electrode, or a conductive carbon electrode.

20. The method according to claim 11 , wherein the magnetron sputtering satisfies at least one of:

a sputtering air pressure is 2× 10 −3 mbar to 8×10 −3 mbar;

a gas flow rate is 50 sccm to 250 sccm;

a heating temperature is 0° C. to 200° C.;

a sputtering power is 200 W to 13 KW; or

a target base spacing is 60 mm to 120 mm.