Large-area devices with high power-conversion efficiency (PCE) are required for the further development of perovskite solar cells (PSCs). However, the major obstacle restricting the commercialization of large-area PSCs is the lack of reliable deposition technology for scalable perovskite thin films. Herein, a confined space sublimation method compatible with the preparation of a large-area perovskite film is introduced. First, pure PbX2 (X is I, Br, and Cl) films are exposed to CH3NH3I vapor, and the gas-solid reaction mechanisms for different lead halide layers are investigated; the perovskite films fabricated by retarded displacement between multiple halogens show large grains and a controllable band gap. Then, through mixed halogen adjustments of the PbX2 film, a maximum PCE of 20.44% (0.07 cm2) for high-efficiency PSCs with large grains (over 2.0 μm) is obtained, while the fabrication of wide-band gap PSCs with a champion PCE of 17.99% (0.07 cm2) verified the band gap-controlled compatibility of the confined space sublimation approach. Furthermore, the confined space sublimation approach is applied to fabricate large-area (6.75 cm2) devices with uniform photovoltaic performance, demonstrating the scalable potential of this approach.
Keywords: CH3NH3I vapor; confined space sublimation; controllable band gap; large area; large grain.