Charge transport varnish

A charge-transporting varnish comprising a charge-transporting substance, an electron-accepting dopant substance and an organic solvent, wherein the electron-accepting dopant substance includes at least one compound selected from the group consisting of 1,5-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, 1,3,5-naphthalenetrisulfonic acid, 1,3,6-naphthalenetrisulfonic acid;

• and 1,4,5,7-naphthalenetetrasulfonic acid, wherein the charge-transporting substance is at least one selected from the group consisting of aniline derivatives and thiophene derivatives of formulas (H2) to (H3) below,
• in formula (H2), R7 to R10 are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxyl group, a thiol group, a phosphoric acid group, a sulfonic acid group, a carboxyl group, an alkoxy group of 1 to 20 carbon atoms, thioalkoxy group of 1 to 20 carbon atoms, alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms or alkynyl group of 2 to 20 carbon atoms which may be substituted with Z1, an aryl group of 6 to 20 carbon atoms or aralkyl group of 7 to 20 carbon atoms which may be substituted with Z2, or an acyl group of 1 to 20 carbon atoms;
• R11 to R14 are each independently a hydrogen atom, a phenyl group, a naphthyl group, a pyridyl group, a pyrimidinyl group, a pyridazinyl group, a pyrazinyl group, a furanyl group, a pyrrolyl group, a pyrazolyl group, a imidazolyl group or a thienyl group, which groups may be substituted with a halogen atom, a nitro group, a cyano group, a hydroxyl group, a thiol group, a phosphoric acid group, a sulfonic acid group, a carboxyl group, an alkoxy group of 1 to 20 carbon atoms, a thioalkoxy group of 1 to 20 carbon atoms, an alkyl group of 1 to 20 carbon atoms, a haloalkyl group of 1 to 20 carbon atoms, an alkenyl group of 2 to 20 carbon atoms, an alkynyl group of 2 to 20 carbon atoms, an aryl group of 6 to 20 carbon atoms, an aralkyl group of 7 to 20 carbon atoms, or an acyl group of 1 to 20 carbon atoms, or a group of formula (H4), provided that at least one of R11 to R14 is a hydrogen atom;
• m is an integer from 2 to 5;
• and Z1 is a halogen atom, a nitro group, a cyano group, an amino group, or an aryl group of 6 to 20 carbon atoms or heteroaryl group of 2 to 20 carbon atoms which may be substituted with Z3;
• Z2 is a halogen atom, a nitro group, a cyano group, an amino group, or an alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms or alkynyl group of 2 to 20 carbon atoms which may be substituted with Z3;
• Z3 is a halogen atom, a nitro group, a cyano group, or an amino group,
• in formula (H4), R15 to R18 are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxyl group, a thiol group, a phosphoric acid group, a sulfonic acid group, a carboxyl group, an alkoxy group of 1 to 20 carbon atoms, thioalkoxy group of 1 to 20 carbon atoms, alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms or alkynyl group of 2 to 20 carbon atoms which may be substituted with Z1, an aryl group of 6 to 20 carbon atoms or aralkyl group of 7 to 20 carbon atoms which may be substituted with Z2, or an acyl group of 1 to 20 carbon atoms;
• R19 and R20 are each independently a phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a pyrimidinyl group, a pyridazinyl group, a pyrazinyl group, a furanyl group, a pyrrolyl group, a pyrazolyl group, an imidazolyl group or a thienyl group, which groups may be bonded to each other to form a ring or may be substituted with a halogen atom, a nitro group, a cyano group, a hydroxyl group, a thiol group, a phosphoric acid group, a sulfonic acid group, a carboxyl group, an alkoxy group of 1 to 20 carbon atoms, a thioalkoxy group of 1 to 20 carbon atoms, an alkyl group of 1 to 20 carbon atoms, a haloalkyl group of 1 to 20 carbon atoms, an alkenyl group of 2 to 20 carbon atoms, an alkynyl group of 2 to 20 carbon atoms, an aryl group of 6 to 20 carbon atoms, an aralkyl group of 7 to 20 carbon atoms, or an acyl group of 1 to 20 carbon atoms;
• and Z1 and Z2 are as defined above,
• in formula (H3), R21 to R24 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a silanol group, a thiol group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a phosphoric acid ester group, an ester group, a thioester group, an amide group, a nitro group, an alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms or alkynyl group of 2 to 20 carbon atoms which may be substituted with Z1, an aryl group of 6 to 20 carbon atoms or aralkyl group of 7 to 20 carbon atoms which may be substituted with Z2, an acyl group of 1 to 20 carbon atoms, a sulfonic acid group, or a —NHY1, —NY2Y3, —OY4, —SY5 or —SiY6Y7Y8 group;
• Y1 to Y8 are each independently an alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms or alkynyl group of 2 to 20 carbon atoms which may be substituted with Z1, or an aryl group of 6 to 20 carbon atoms or heteroaryl group of 2 to 20 carbon atoms which may be substituted with Z2;
• X and Y are each independently a thiophene ring which may be substituted with Z2;
• the two sulfur atoms included on the dithiine ring may be each independently a SO group or a SO2 group;
• p, q and r are each independently 0 or an integer of 1 or more, these being numbers that together satisfy the condition p+q+r≤20;
• and Z1 and Z2 are as defined above.