Electrochromic element, optical density changing element, optical element and photographing unit

An electrochromic element comprising:

• a semiconductor material which is a nanoporous semiconductor material having a roughness factor of 20 or higher;
• and
• an electrochromic material on a surface of the semiconductor material, the electrochromic material comprising at least one of electrochromic materials represented by formulas (1), (2) and (3):
• wherein V1, V2, V3, V4, V5, V6, V7, V8, V9, V10, V11, V12, V13, V14, V15, V16, V17, V18, V19, V20, V21, V22, V23 and V24 each independently represents a hydrogen atom or a monovalent substituent;
• R1, R2, R3, R4, R5 and R6 each independently represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group;
• L1, L2, L3, L4, L5 and L6 each independently represents a methine group or a nitrogen atom;
• n1, n2 and n3 each independently represents 0, 1, 2 or 3;
• M1, M2 and M3 each independently represents a charge balancing counter ion, and m1, m2 and m3 each independently represents a number equal to or larger than 0 necessary for neutralizing a charge of a molecule;
• and
• in the case n1, n2 and n3 are 0, R1, R2, R3, R4, R5 and R each independently represents an aryl group, and compounds represented by the formulas (1) to (3) each independently has at least a group selected from a sulfo group, a phosphono group and a phosphato group.