  Using an innovative combination of multi-beam-optical stress-sensor (MOSS)
curvature and X-ray diffraction (XRD) techniques, the Young's modulus (E) of
polycrystalline MAPbI3 metal-halide perovskite (MHP) thin films attached to Si
substrates is estimated to be 10.2 +/- 3.4 GPa. This is comparable to the E of
corresponding MAPbI3 single-crystals. This generic method could be applied to
other systems to estimate hard-to-measure E of thin films.
