Organic proton-type ionic liquid, two-dimensional perovskite pure-phase quantum well film, preparation method and use thereof

A method for preparing a film with a two-dimensional perovskite pure-phase quantum well structure, the two-dimensional perovskite pure-phase quantum well structure having a chemical formula of AaBbMmXx, where A is a carbon chain organic cation, and a-value ranges from 0 to 2.5;

• B is an amine group-containing monovalent cation, b-value satisfies 0≤b<m+1, and m is any natural number and satisfies m−1≥0;
• M is a divalent metal cation;
• and X is one or more of halogen ion, carboxylate ion and thiocyanate ion, and x-value satisfies 3m−1<x≤3m+1;
• the method comprising:
• 1) Adding BX to a DMSO solution to prepare a DMSO mixture with a BX mass fraction of 1-35%;
• 2) Adding an organic proton-type ionic liquid to the DMSO mixture prepared in step 1), mixing, stirring at 25° C. for 2 hours, and then adding MX2 thereto;
• 3) Then adding 1600 μL of a DMF reagent, heating to 65° C. and stirring until dissolved, and cooling to room temperature to obtain a mixed solution;
• and
• 4) Spin-coating the mixed solution prepared in step 3) while heating onto a surface of a glass substrate in air with a humidity of 20%-80%, and maintaining at a temperature of 25° C.-250° C. to obtain the film with the two-dimensional perovskite pure-phase quantum well structure;
• wherein a molar ratio of the organic proton-type ionic liquid, the BX, and the MX2 is 2:m+1:m;
• the BX is a compound salt of a monovalent cation;
• the MX2 is a compound formed by a divalent metal cation and an X ion;
• the organic proton-type ionic liquid serves as a source of A, and has a chemical formula of RNH3+·CH3COO− where R represents an alkyl group of C4-8 or a phenyl group, or a chemical formula of RNH3+·RCOO− where R represents an alkyl group of C4-8 or a phenyl group;
• and
• the A corresponds to RNH3+ of the organic proton-type ionic liquid.