PEROVSKITE SOLAR CELL AND PHOTOVOLTAIC MODULE

1 . A perovskite solar cell, comprising

a perovskite layer comprising a first surface and a second surface that are opposite each other in the thickness direction thereof;

a hole transport layer provided on the first surface; and

an electron transport layer provided on the second surface, wherein the electron transport layer comprises a doping material and at least two sub-layers having a conduction band bottom energy level lower than that of the hole transport layer and a valence band top energy level lower than that of the hole transport layer.

2 . The perovskite solar cell according to claim 1 , wherein:

the difference between the conduction band bottom energy levels of the sub-layer of the electron transport layer that is close to the second surface and the perovskite layer is −1.0 eV-1.0 eV, and optionally, the difference between the conduction band bottom energy levels of the sub-layer and the perovskite layer is −0.3 eV-0.3 eV.

3 . The perovskite solar cell according to claim 1 , wherein:

the valence band top energy level of the sub-layer of the electron transport layer that is close to the second surface is lower than that of the perovskite layer.

4 . The perovskite solar cell according to claim 1 , wherein:

the difference between the Fermi levels of the sub-layer of the electron transport layer that is close to the second surface and the perovskite layer is ≤1.5 eV.

5 . The perovskite solar cell according to claim 1 , wherein:

the difference between the conduction band bottom energy level and the Fermi level of the sub-layer of the electron transport layer that is close to the second surface is ≤1.5 eV.

6 . The perovskite solar cell according to claim 1 , wherein:

the difference between the conduction band bottom energy level and the valence band top energy level of the sub-layer of the electron transport layer that is close to the second surface is ≥ 1.5 eV.

7 . The perovskite solar cell according to claim 1 , wherein the electron transport layer comprises a first sub-layer, a second sub-layer and a third sub-layer that are stacked sequentially in the direction away from the second surface, wherein the first sub-layer is a tin oxide layer comprising a first doping material, and the first doping material comprises an alkali metal, an alkaline earth metal, a transition metal, a poor metal, a metalloid, a non-metallic element, an ionic liquid, a carboxylic acid, a phosphoric acid, a carbon derivative, a self-assembled single molecule or an organic polymer.

8 . The perovskite solar cell according to claim 7 , wherein:

the alkali metal includes at least one of Li, K, Na, Rb and Cs;

the alkaline earth metal includes at least one of Be, Sr and Ba;

the transition metal includes at least one of Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, Pt and Au;

the poor metal includes at least one of Al, Ga, In, Sn, Tl, Pb and Bi;

the metalloid includes at least one of B, Si, Ge, As, Sb and Te;

the non-metallic element includes at least one of F, Cl, Br, I, P, S and Se;

the ionic liquid includes at least one of 1-butyl-3-methylimidazolium tetrafluoroborate, ammonium chloride, ammonium sulfide, tetramethylammonium hydroxide and 2,2,2-trifluoroethanol;

the carboxylic acid includes at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 4-imidazoleacetic acid hydrochloride, and acetic acid;

the carbon derivative includes at least one of carbon quantum dots, carbon nanotubes, graphene, carbon 60, carbon 60 derivatives, graphitic carbon nitride and carbon 9;

the self-assembled single molecule includes at least one of 4-pyridinecarboxylic acid, dopamine, 3-aminopropyltriethoxysilane and glycine; and

the organic polymer includes at least one of polystyrene, polyethylenimine ethoxylated, polyethylene oxide, and triphenylphosphine oxide.

9 . The perovskite solar cell according to claim 7 , wherein:

the second sub-layer comprises an imide compound layer, a quinone compound layer, a fullerene layer, a perovskite oxide layer, a fluoride layer, or an oxide layer.

10 . The perovskite solar cell according to claim 9 , wherein:

the imide compound layer comprises an imide compound or a derivative of the imide compound, and the imide compound includes phthalamide, succinimide, N-bromosuccinimide, glutarimide or maleimide;

the quinone compound layer comprises a quinone compound or a derivative of the quinone compound, and the quinone compound includes benzoquinone, naphthoquinone, phenanthrenequinone or anthraquinone;

the perovskite oxide layer comprises strontium titanate, calcium titanate, barium titanate, lithium titanate, iron(II) titanium oxide, nickel titanate or cobalt titanate;

the fluoride layer comprises lithium fluoride or calcium fluoride; and

the oxide layer comprises an oxide layer of the following elements: Ce, Mg, Si, Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga or Cr.

11 . The perovskite solar cell according to claim 7 , wherein the third sub-layer comprises a metal oxide layer or a metal oxide layer comprising a second doping material, and the metal oxide layer includes a SnO 2 layer, a In 2 O 3 layer, a ZnO layer, a CdO layer, a NiO layer, a CdIn 2 O 4 layer, a Cd 2 SnO 4 layer, a Zn 2 SnO 4 layer, a MgIn 2 O 4 layer, a ZnIn 2 O 4 layer, a CoIn 3 O 6 layer, a ZnV 2 O 6 layer, a CuAlO 2 layer, or a CuGaO 2 layer.

12 . The perovskite solar cell according to claim 11 , wherein:

the SnO 2 layer comprises a second doping material, the element of which comprises at least one of F, Sb, P, As, Te and Cl;

the In 2 O 3 layer comprises a second doping material, the element of which comprises at least one of W, Mn, Zr, Ti, Sb, F and Ag; and

the ZnO layer comprises a second doping material, the element of which comprises at least one of Ga, In, F, N, B and Al.

13 . A photovoltaic module comprising the perovskite solar cell according to claim 1 .