The mechanical behavior of metal-halide perovskites: Elasticity, plasticity, fracture, and creep

Wide ranging mechanical properties - elasticity, plasticity, fracture, and creep - most relevant to the mechanical reliability of perovskite solar cells (PSCs) are systematically investigated. High quality bulk single-crystals of the commonly studied metal-halide perovskites (MHPs) relevant to PSCs are fabricated and studied: CH3NH3PbBr3 (MAPbBr(3)) and CH3NH3PbI3 (MAPbI(3)). The first direct measurement of MHP Young's modulus (E) using uniaxial compression reveals E-<100> of 13.1 +/- 1.3 and 10.6 +/- 1.0 GPa for MAPbBr(3) and MAPbI(3), respectively. The Vickers micro-hardness H(100) of MAPbBr(3) and MAPbI(3) is 0.54 +/- 0.02 GPa and 0.76 +/- 0.05 GPa, respectively. The Vickers micro-indentation fracture toughness KIC of MAPbBr(3) and MAPbI(3) is estimated at 0.20 +/- 0.03 MPa.m(0.5) and 0.18 +/- 0.03 MPa.m(0.5), respectively. The stress-exponent, n, extracted from nanoindentation creep data is similar to 8 and similar to 10 for MAPbBr(3) and MAPbI(3), respectively. The trends in these properties are discussed. These properties are best estimates and are recommended for use in future mechanical behavior and reliability analyses of MHPs and PSCs.

Automated summary

In this study, the mechanical properties, including elasticity, plasticity, fracture, and creep, relevant to the mechanical reliability of perovskite solar cells (PSCs), were systematically investigated. High-quality single-crystals of commonly studied metal-halide perovskites (MHPs) were fabricated and studied. The results provide important parameters for future mechanical behavior and reliability analysis of MHPs and PSCs.