Overcoming the Anisotropic Growth Limitations of Free-Standing Single-Crystal Halide Perovskite Films

It is extremely challenging to grow single-crystal halide perovskite films (SCHPFs) with not only desired transport properties but also large lateral size with much thinner thickness. Here, we report the growth of freestanding single crystal CsPbBr₃ SCHPFs with thickness less than 100 nm and a lateral size close to centimeter for the first time. A new model for growth kinetics (Ψ=Aexp[−(E_A−E_s)/(k_BT)]) is proposed to address the surface energy and temperature effect on the growth rate of ultrathin CsPbBr₃ single-crystal film. The experimental results and DFT calculations both demonstrated that the surfactant plays a critical role in modifying the surface energy and achieving anisotropic growth. This work opens new opportunities for high-quality SCHPFs with large lateral size and controllable thickness that may find wide applications for optoelectronic devices.