System and method for fabricating perovskite film for solar cell applications

A method for fabricating a perovskite film for solar cell applications, by

• using source materials AX and BX2, wherein the AX is an organic material and the BX2 is a metal halide material, wherein the halogen X in the AX and the halogen X in the BX2 are the same element or different elements, and by using a system comprising:
• a housing for use as a vacuum chamber, the housing having a side section along a vertical direction and top and bottom sections along a horizontal direction;
• a substrate stage coupled to the top section of the housing and configured to have a stage surface facing vertically downward for a substrate to be placed on;
• a first evaporator unit coupled to the bottom section of the housing and configured to generate BX2 vapor, the first evaporator unit comprising a crucible and a heater element contacting the crucible;
• a second evaporator unit coupled to the housing and configured to generate AX vapor;
• a flow control unit coupled to the housing for controlling circulation of the AX vapor in the housing, the flow control unit selected from the group consisting of a fan, foreline pump and a combination thereof;
• a gate valve coupled between the housing and a pump unit for controlling pressure inside the housing;
• a first shutter provided below the substrate stage and configured to be moved to expose or cover the substrate stage;
• and
• a second shutter provided above the first evaporator unit and configured to be moved to expose or cover the first evaporator unit, the method comprising:
• controlling temperature of the substrate stage for providing uniform cooling or heating to the substrate;
• moving the first shutter to cover the substrate;
• moving the second shutter to expose the first evaporator unit;
• opening the gate valve to a first position;
• controlling a first evaporation temperature associated with the first evaporator unit to adjust a first evaporation rate for generating the BX2 vapor;
• controlling a second evaporation temperature associated with the second evaporator unit to adjust a second evaporation rate for generating the AX vapor, the second evaporation temperature being lower than the first evaporation temperature;
• controlling the flow control unit to control the circulation of the AX vapor;
• moving the first shutter to expose the substrate;
• monitoring thickness of the perovskite film growing on the substrate;
• moving the first shutter to cover the substrate when the thickness of the perovskite film reaches a predetermined thickness;
• terminating heating of the first and second evaporator units;
• and
• opening the gate valve to a second position to pump out remaining vapor inside the housing,
• wherein a center of the substrate stage and a center of the first evaporator unit are vertically aligned, and
• wherein dimensions of a horizontal cross-sectional shape of the first evaporator unit, dimensions of a horizontal cross-sectional shape of the substrate stage, and a relative position in the horizontal direction between the two horizontal cross-sectional shapes are configured to maximize an overlap between the two horizontal cross-sectional shapes.