A system comprising: a housing (100; 700) for use as a vacuum chamber, the housing (100; 700) having a side section along a vertical direction and top and bottom sections along a horizontal direction; a substrate stage (112; 712) coupled to the top section of the housing (100; 700) and configured to have a stage surface facing vertically downward for a substrate (116; 716) to be placed on; a first evaporator unit (120; 720) coupled to the bottom section of the housing (100; 700) and configured to generate a first vapor; a second evaporator unit (124; 724) coupled to the housing (100; 700) and configured to generate a second vapor; and a flow control unit (128; 728) coupled to the housing (100; 700) and operable to control circulation of the second vapor in the housing (100; 700) so as to cause a uniform flow of the second vapor over the substrate (116; 716), wherein: the system is configured to fabricate a perovskite film for solar cell applications from the first and second vapors, the second vapor being AX vapor and the first vapor being BX 2 vapor, wherein the AX is an organic material having an organic element A selected from a group consisting of methylammonium, formamidinium and 5-aminovaleric acid (5-AVA) and a halogen element X selected from a group consisting of Cl, I and Br, or a combination of two or more of the organic materials; and the BX 2 is a metal halide material having a metal element B selected from a group consisting of Pb and Sn and a halogen element X selected from a group consisting of Cl, I and Br, or a combination of two or more of the metal halide materials, and position of the second evaporator unit (124; 724) in the housing, dimensions of a horizontal cross-sectional shape of the first evaporator unit (120; 720), dimensions of a horizontal cross-sectional shape of the substrate stage (112; 712), 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. a housing (100; 700) for use as a vacuum chamber, the housing (100; 700) having a side section along a vertical direction and top and bottom sections along a horizontal direction; a substrate stage (112; 712) coupled to the top section of the housing (100; 700) and configured to have a stage surface facing vertically downward for a substrate (116; 716) to be placed on; a first evaporator unit (120; 720) coupled to the bottom section of the housing (100; 700) and configured to generate a first vapor; a second evaporator unit (124; 724) coupled to the housing (100; 700) and configured to generate a second vapor; and a flow control unit (128; 728) coupled to the housing (100; 700) and operable to control circulation of the second vapor in the housing (100; 700) so as to cause a uniform flow of the second vapor over the substrate (116; 716), wherein: the system is configured to fabricate a perovskite film for solar cell applications from the first and second vapors, the second vapor being AX vapor and the first vapor being BX 2 vapor, wherein the AX is an organic material having an organic element A selected from a group consisting of methylammonium, formamidinium and 5-aminovaleric acid (5-AVA) and a halogen element X selected from a group consisting of Cl, I and Br, or a combination of two or more of the organic materials; and the BX 2 is a metal halide material having a metal element B selected from a group consisting of Pb and Sn and a halogen element X selected from a group consisting of Cl, I and Br, or a combination of two or more of the metal halide materials, and position of the second evaporator unit (124; 724) in the housing, dimensions of a horizontal cross-sectional shape of the first evaporator unit (120; 720), dimensions of a horizontal cross-sectional shape of the substrate stage (112; 712), 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. the system is configured to fabricate a perovskite film for solar cell applications from the first and second vapors, the second vapor being AX vapor and the first vapor being BX 2 vapor, wherein the AX is an organic material having an organic element A selected from a group consisting of methylammonium, formamidinium and 5-aminovaleric acid (5-AVA) and a halogen element X selected from a group consisting of Cl, I and Br, or a combination of two or more of the organic materials; and the BX 2 is a metal halide material having a metal element B selected from a group consisting of Pb and Sn and a halogen element X selected from a group consisting of Cl, I and Br, or a combination of two or more of the metal halide materials, and position of the second evaporator unit (124; 724) in the housing, dimensions of a horizontal cross-sectional shape of the first evaporator unit (120; 720), dimensions of a horizontal cross-sectional shape of the substrate stage (112; 712), 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.