Solid electrolyte, secondary battery and capacitor

A solid electrolyte comprising:

• a molecular crystal, and
• an inorganic filler that includes an inorganic oxide, wherein the molecular crystal includes an ionic compound including a cation of a monovalent to trivalent metal atom, an anion, and a ligand of the ionic compound and the molecular crystal includes at least one selected from the group consisting of [LIN(SO2F)2(NCCH2CH2CN)2]n, [Li2{N(SO2CF3)2}2(NCCH2CH2CN)3]n, [Li{N(SO2CF3)2}{(CH3)2NCH2CH2N(CH3)2}]n, [Li{N(SO2CF2)2CF2X(CH3)2NCH2CH2N(CH3)2}]n and [Li{N(SO2C4F9)2HC6H4(OCH3)2}]n, wherein each n independently represents an integer of 1 or more.