Organic-inorganic hybrid perovskites have been emerging as promising light-harvesting materials for high-efficiency solar cells recently. Compared to solution-based methods, vapor-based deposition technologies are more suitable in preparing compact, uniform, and large-scale perovskite thin films. Here, we utilized flash-evaporation printing (FEP), a laser-induced ultrafast single source evaporation method employing a carbon nanotube evaporator, to fabricate high-quality methylammonium lead iodide perovskite thin films. Stoichiometric films with pure tetragonal perovskite phase can be achieved using a controlled methylammonium iodide to lead iodide ratio in evaporation precursors. The film crystallinity and crystal grain growth could further be promoted after postannealing. Planar solar cells (0.06 cm2) employing these perovskite films exhibit a champion power conversion efficiency (PCE) of 16.8% with insignificant hysteresis, which is among the highest reported PCEs using vapor-based deposition methods. Large-area (1 cm2) devices based on such perovskite films also achieved a stabilized PCE of 11.2%, indicating the feasibility and scalability of our FEP method in fabricating large-area perovskite films for other optoelectronic applications.
Keywords: carbon nanotube evaporator; crystallinity; perovskite solar cells; single source evaporation; stoichiometry.