Film morphology and the corresponding structural configuration can profoundly affect the optical performance, especially the random lasing action in organic-inorganic metal-halide perovskite thin films. They can be controlled in both micro- and nano-scale by manipulating different processing parameters such as the ratios of engineered solvent mixtures, spin-coating speed and backplane temperature. With the optimized parameters, the synthesized bare perovskite thin films can achieve room-temperature random lasing action with the energy pumping threshold down to 0.9 mJ cm-2 and the corresponding β factor is estimated to be about 0.14. The bare films also show a long-time lasing reliability, maintaining lasing intensity after an optical pumping of 12 × 105 pulses. Meanwhile, in the lifetime test under ambient conditions, the bare films can sustain up to 7 days without any sealing package. Moreover, the perovskite thin films can also be synthesized on flexible substrates with the total area up to 100 cm2, paving a potential way for fabricating large-area and flexible random lasers in speckle-free laser projection and imaging.
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