Photoelectric conversion element and solar cell

A photoelectric conversion element comprising:

• a first electrode;
• an electron transport layer on the first electrode, the electron transport layer comprising an electron transport compound, the electron transport compound carrying:
• a compound represented by the following formula (1):
• where each of X1 and X2 independently represents oxygen atom, sulfur atom, or selenium atom;
• R1 represents methine group;
• R2 represents an alkyl group, an aryl group, or a heterocyclic group;
• each of R3 independently represents an acidic group;
• m represents an integer of 1 or 2;
• and each of Z1 and Z2 independently represents a group forming a cyclic structure;
• and
• a compound represented by the following formula (2):
• R5—R4—COOH Formula (2)
• where R4 represents an aryl group or a heterocyclic group;
• and R5 represents an alkyl group, an alkoxy group, an alkenyl group, an alkylthio group, or an aryl ether group;
• a charge transfer layer;
• and
• a second electrode;
• and wherein the compound represented by the formula (1) is represented by the following formula (4):
• where each of X1 and X2 independently represents oxygen atom or sulfur atom;
• R2 represents an alkyl group, an aryl group, or a heterocyclic group;
• each of R3 independently represents an acidic group;
• and each of R6 and R7 independently represents an alkyl group, an aryl group, or a non-cyclic structure, or R6 and R7 share bond connectivity to form a cyclic structure.