Preparation process of perovskite thin films

(1) Measure 20 mL of hydroiodic acid and 14 mL of methylamine solution, put them into a beaker and stir in an ice bath for 2 h, then heat in a Water Bath at 70 °C for 6 h to obtain a crude product of methylamine iodide. Then use a centrifuge to wash it successively with ethanol and ether. After repeated washing for 3 times, white methylamine iodide crystals are obtained. After vacuum drying at 60°C for 24 hours, dissolve in a certain amount of ethanol under heating conditions, and wait until completely After dissolution, the temperature of the solution was lowered to 0. Below C, recrystallize and dry under vacuum again, and finally get pure CHNH3I crystal powder.

(2) First weigh 200 mg of PbI2 solid powder, then measure 1 mL of DMF solution and add it dropwise to PbI2 solid powder, and stir at 60 C for 6 h to obtain a transparent orange-yellow precursor solution. Then, after preheating the obtained precursor solution at 70°C for 30min, it was added dropwise on the cleaned FTO glass, and was spin-coated with a vacuum Spin Coater (3000 rotations, 30s) to form a uniform film, and then the obtained The PbI film placed in a Drying Oven was heated and dried at 70 °C for 30 min, and then taken out for use.

(3) Take out a small amount of CH3NH3I powder in step (1) and fully grind it with an agate mortar for 15 minutes, then spread it evenly on the PbI2 film, and then place the FTO glass covered with the PbI2 film of CH3NH3I powder on the hot stage slowly Raise the temperature to 80°C (start from room temperature and keep the surrounding air dry, relative humidity <50), and heat the stage to 80°C at a rate of 6 C/min. Slow heating is beneficial to intensify the random movement of CH3NH3I molecules under thermodynamic action , providing sufficient reaction time for the construction of perovskite CHNH3PbI films. After the temperature reached 80 °C, the reaction was kept for 1 min, and then the glass piece was removed to remove excess CH3NH3I powder, then washed with isopropanol and dried , and finally the obtained sample was sealed and kept in a dark place.

This experiment mainly carries out the research of two aspects: 1. the influence of temperature on film formation, by in 80 DEG C, 90 DEG C, 100 DEG C, 110 DEG C, 120 DEG C, 140 DEG C temperature ranges, seek suitable reaction temperature; 2. . The influence of time on film formation, through. Within 1-15min, explore the appropriate reaction time.