Polyimide, method for preparing the same, and flexible oled panel

A method for preparing a polyimide, comprising:

• a step S1 of dissolving a diaminocarbazole derivative
• and a dianhydride monomer
• in a first organic solvent under argon gas protection, and stirring and reacting for a first time at a first temperature to obtain a first reaction solution,
• wherein R is selected from
• and R1 is a C6-30 aryl group, a C3-30 heteroaryl group, a C6-30 halogenated aryl group, or a C6-30 arylamine group;
• a step S2 of taking the first reaction solution and adding a second organic solvent thereto, raising to a second temperature and reacting for a second time and then cooling to a third temperature under argon gas protection so as to obtain a reaction solution, and performing filtration on the obtained reaction solution using an organic filter membrane to obtain a filtrate;
• a step S3 of coating the filtrate on a substrate, drying in a vacuum environment at a fourth temperature to remove 60 to 80 wt % of the first organic solvent and the second organic solvent, and then transferring into a high temperature furnace to heat at a fifth temperature, so as to obtain the substrate attached with a thin film;
• and
• a step S4 of immersing the substrate attached with the thin film in deionized water for a third time, peeling off the thin film attached on the substrate, and then drying the thin film at a sixth temperature to obtain a polyimide film.