  The remarkable optoelectronic, and especially photovoltaic performance of
hybrid-organic-inorganic perovskite (HOIP) materials drives efforts to connect
materials properties to this performance. From nano-indentation experiments on
solution-grown single crystals we obtain elastic modulus and nano-hardness
values of APbX3 (A = Cs, CH3NH3 and X = I, Br). The Youngs moduli are about 14,
19.5 and 16 GPa, for CH3NH3PbI3, CH3NH3PbBr3 and CsPbBr3, respectively, lending
credence to theoretically calculated values. We discuss possible relevance of
our results to suggested self-healing, ion diffusion and ease of manufacturing.
Using our results, together with literature data on elastic moduli, we
classified HOIPs amongst relevant materials groups, based on their
elasto-mechanical properties.
