Polycyclic aromatic compound

A polycyclic aromatic compound or a salt thereof having a partial structure represented by the following general formula (I):

• wherein
• X represents B, P, P═O, P═S, P═Se, As, As═O, As═S, As═Se, Sb, Sb═O, Sb═S, Sb═Se, an optionally substituted metal in groups 3 to 11 in the periodic table, or an optionally substituted metal or metalloid in group 13 or 14 of the periodic table;
• and
• Ring A, ring B, ring C, and ring D are the same or different, and each represents an optionally substituted aromatic ring or an optionally substituted heteroaromatic ring.