FULLERENE DERIVATIVES AND PEROVSKITE SOLAR BATTERIES

1 . A fullerene derivative having a C60 fullerene group and a group of a compound of formula (1), a compound of formula (2), and/or a compound of formula (3) attached to the C60 fullerene group, wherein structural formulas of the compounds of formula (1), formula (2), and formula (3) are as follows:

wherein:

R 1 , R 4 , and R 7 are each independently selected from R′, a phenyl group, a naphthyl group, a biphenyl group, R′ substituted with a halogen, a phenyl group substituted with a halogen, a naphthyl group substituted with a halogen, a biphenyl group substituted with a halogen, a nitrogen-containing group, R′ substituted with a nitrogen-containing group, a phenyl group substituted with a nitrogen-containing group, a naphthyl group substituted with a nitrogen-containing group, or a biphenyl group substituted with a nitrogen-containing group;

R 2 , R 5 , and R 8 are each independently selected from hydrogen or R′;

R 3 , R 6 , and R 9 are each independently selected from hydrogen, halogen, —O—R, a nitrogen-containing group, —OH, —OR, —NHCOR, —OCOR, —R, —CH 2 COOH, a phenyl group, or a naphthyl group;

the nitrogen-containing group is -N(R) 2 , —NHR, —NH 2 , a trimethylamine group, a triethylamine group, or a tripropylamine group;

R′ is an alkyl group with 1-5 carbon atoms;

R is an alkyl group with 1-10 carbon atoms; and

n1, n2, n3, m1, m2, and m3 are each independently an integer in the range of 0-10, n1 + m1 ≤ 10, n2 + m2 ≤ 10, and n3 + m3 ≤ 10.

2 . The fullerene derivative according to claim 1 , wherein:

R 1 is selected from R′;

R 2 and R 5 are hydrogen;

R 3 is hydrogen;

R 4 is selected from R′, a phenyl group or a trimethylamine group;

R 6 is selected from hydrogen or halogen, optionally hydrogen or fluorine;

n1 + m1 ≤ 5; and

n2 + m2 ≤ 5.

3 . The fullerene derivative according to claim 1 , wherein the C60 fullerene group is attached with 1-3 groups selected from the groups of compounds of formula (1), formula (2), and/or formula (3).

4 . The fullerene derivative according to claim 1 , wherein the LUMO energy level of the fullerene derivatives ranges from -4.02 to -3.72 eV.

5 . The fullerene derivative according to claim 1 , wherein the fullerene derivative has a structure of formula (4), formula (5), formula (6), formula (7), formula (8), formula (9), formula (10), formula (11), or formula (12):

wherein R 1 to R 9 , n1 to n3, and m1 to m3 are as defined in claim 1 .

6 . A perovskite solar battery comprising:

conductive glass;

a hole transport layer;

a perovskite layer; and

an electron transport layer comprising a fullerene derivative and a back electrode, the fullerene derivative having a C60 fullerene group and a group of a compound of formula (1), a compound of formula (2), and/or a compound of formula (3) attached to the C60 fullerene group, wherein structural formulas of the compounds of formula (1), formula (2), and formula (3) are as follows:

wherein:

R 1 , R 4 , and R 7 are each independently selected from R′, a phenyl group, a naphthyl group, a biphenyl group, R′ substituted with a halogen, a phenyl group substituted with a halogen, a naphthyl group substituted with a halogen, a biphenyl group substituted with a halogen, a nitrogen-containing group, R′ substituted with a nitrogen-containing group, a phenyl group substituted with a nitrogen-containing group, a naphthyl group substituted with a nitrogen-containing group, or a biphenyl group substituted with a nitrogen-containing group;

R 2 , R 5 , and R 8 are each independently selected from hydrogen or R′;

R 3 , R 6 , and R 9 are each independently selected from hydrogen, halogen, —O—R, a nitrogen-containing group, —OH, —OR, —NHCOR, —OCOR, —R, —CH 2 COOH, a phenyl group, or a naphthyl group;

the nitrogen-containing group is -N(R) 2 , —NHR, —NH 2 , a trimethylamine group, a triethylamine group, or a tripropylamine group;

R′ is an alkyl group with 1-5 carbon atoms;

R is an alkyl group with 1-10 carbon atoms; and

n1, n2, n3, m1, m2, and m3 are each independently an integer in the range of 0-10, n1 + m1 ≤ 10, n2 + m2 ≤ 10, and n3 + m3 ≤ 10.

7 . The perovskite solar battery according to claim 6 , wherein the perovskite solar battery is an inverted perovskite solar battery.

8 . The perovskite solar battery according to claim 6 , wherein the LUMO energy level of the electron transport layer is greater than or equal to the LUMO energy level of the perovskite layer, and a difference between the LUMO energy levels of the electron transport layer and the perovskite layer is in the range of 0 to 0.2 eV.

9 . The perovskite solar battery according to claim 6 , wherein no passivation layer is comprised between the perovskite layer and the electron transport layer.