Solid electrolytic capacitor and method for producing the same

A solid electrolytic capacitor comprising a valve acting metal having pores, a dielectric film formed on a surface of the valve acting metal, and a solid electrolyte layer provided on the dielectric film, wherein at least a portion of the solid electrolyte layer is of a lamellar structure,

• in which the solid electrolyte layer comprises a composition containing a π-electron conjugate polymer and/or other electrically conducting polymer, in which the electrically conducting polymer is a condensed heteropolycyclic polymer comprising as a repeating unit a structural unit represented by general formula (III) below
• wherein the substituents R6, R7, R8, R9, R10 and R11 each independently represents a monovalent group selected from the group consisting of a hydrogen atom, a linear or branched, saturated or unsaturated C1-10 alkyl, alkoxy or alkyl ester group, a halogen atom, a nitro group, a cyano group, a primary, secondary or tertiary amino group, a trihalomethyl group, a phenyl group and a substituted phenyl group, the alkyl chains of R6, R7, R8, R9, R10 and R11 may combine to each other at any position to form at least one divalent chain for forming at least one 3-, 4-, 5-, 6- or 7-membered saturated or unsaturated hydrocarbon cyclic structure together with the carbon atoms to which the substituents are bonded,
• the alkyl group, the alkoxy group or the alkyl ester group of R6, R7, R8, R9, R10 or R11 or the cyclic hydrocarbon chain formed by the substituents may contain any number of any of carbonyl, ether, ester, amide, sulfide, sulfinyl, sulfonyl and imino bonds,
• k represents a number of the condensed ring enclosed by the thiophene ring and the benzene ring having substituents R6 to R9 and represents an integer of from 0 to 3 excluding a form in which all of R6 to R9 represent a hydrogen atom from among derivatives in which k=0, and the condensed ring may optionally contain 1 to 2 nitrogen atoms or N-oxide, δ is in the range of 0 to 1, Z represents an anion, j is a valency of Z and is 1 or 2.