Dynamic structural property of organic-inorganic metal halide perovskite

Abstract

Unique organic-inorganic hybrid semiconducting materials have made a remarkable breakthrough in new class of photovoltaics (PVs). Organic-inorganic metal (Pb and/or Sn) halides (-I, -Br, and -Cl) are the semiconducting absorber with the crystal structure of the famous ''Perovskite''. It is widely called ''perovskite solar cells (PSCs)'' in PV society. Now, the power conversion efficiency (PCE) of PSCs is recorded in 25.5%. Prototypical composition of the absorbers is (A = methylammonium [MA], formamidinium [FA], and Cs), (M = Pb and/or Sn), and (X = I, Br, and Cl) in the form of perovskite AMX 3 . Since the report on the stable all solid-state PSCs in 2012, the average annual growth rate of PCE is well over $10%. Such an outstanding PV performance attracts huge number of scientists in our research society. Their chemical as well as physical properties are dramatically different from monocrystalline Si, GaAs, other III-IV semiconductors, and many oxides with the crystal structure of perovskite. In this review, different fundamental aspects, in particular, the dynamic properties of A site cationic molecules and PbI 6 octahedrons linked with their corners, from other semiconducting and dielectric materials are reviewed and summarized. Upon discussing unique properties, perspectives on the promising PV applications based on the comprehension in dynamic nature of the orientation in A site molecule and PbI 6 octahedron tilting will be given.

Probing the Role of Local Structure in Driving the Stability of Halide Perovskites CH3NH3PbX3

“…Rietveld refinements of the experimental XRD patterns are in agreement with the existence of orthorhombic (Pnma), tetragonal (I4/mcm) and cubic (Pm3m) phases for both the compounds. 18,19,29 The temperature variations of obtained lattice patameters for MAPbI 3 and MAPbBr 3 are plotted in Figure 1c,d, respectively. Refined unit cell parameters (red color in Figure 1c,d) of MAPbI 3 and MAPbBr 3 in orthorhombic phase are consistent with the previous reports with negative thermal expansion coefficient for "a" and positive thermal expansion coefficient for both "b" and "c", whereas total volume expansion is positive (not shown).…”

“…Crystal structure of hybrid lead halide perovskite involves a positively charged organic unit, methylammonium ion (MA + ), with a permanent dipole, located at the center of a lead halide cage. 17,18 These hybrid lead halide perovskites crystallize in orthorhombic phase at low temperature and have high/roomtemperature cubic perovskite phase depending on the halide ion with an intermediate tetragonal phase. 19 Further, it is also observed that the MA + dipoles order in an antiferroelectric arrangement in low-temperature orthorhombic phase; however, the behavior of this MA + dipole and its role in determining the physical and chemical properties in high temperature tetragonal and cubic phase are still developing.…”

A Reparameterized Density Functional Tight-Binding Method for Engineering phase-stable CsPbX\textsubscript{3} Perovskites

“…The resulting material is physically soft and dynamic in nature, [10][11][12][13] significantly affecting its optoelectronic performance and long-term stability.…”

Ferroic Halide Perovskite Optoelectronics

“…Yet, the interpretation of experimental results argues both ferroelectricity and non‐ferroelectricity in CH 3 NH 3 PbI 3 perovskite. [ 3–63 ] This controversy is related to the polarization‐electric hysteresis, the nanoscale domain structure, etc. Consequently, there are also disagreements on the effect of ferroelectricity on photovoltaic action in MHPs, both detrimental effect (e.g., current‐voltage hysteresis) and beneficial effect (e.g., facilitating photogenerated charge carrier dissociation and transport).…”