Molecular ferroelectric contributions to anomalous hysteresis in hybrid perovskite solar cells

Abstract

We report a model describing the molecular orientation disorder in CH 3 NH 3 PbI 3 , solving a classical Hamiltonian parametrised with electronic structure calculations, with the nature of the motions informed by ab-initio molecular dynamics. We investigate the temperature and static electric field dependence of the equilibrium ferroelectric (molecular) domain structure and resulting polarisability. A rich domain structure of twinned molecular dipoles is observed, strongly varying as a function of temperature and applied electric field. We propose that the internal electrical fields associated with microscopic polarisation domains contribute to hysteretic anomalies in the current-voltage response of hybrid organicinorganic perovskite solar cells due to variations in electron-hole recombination in the bulk.

Tunable ferroelectric polarization and its interplay with spin–orbit coupling in tin iodide perovskites

“…Indeed, significant disorder was predicted, for example, for CH 3 NH 3 PbI 3 in ref. 37 from molecular dynamics simulations 37 .…”

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO2: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

“…Several authors have reported on this effect and speculated about the causes. [18][19][20][21][22] Some recent articles present cell designs that minimize this hysteresis. 23,24 In this article, we describe the hysteresis effect in additional detail.…”

Ionic Reactivity at Contacts and Aging of Methylammonium Lead Triiodide Perovskite Solar Cells

“…In spite of the spectacular advances in cell efficiency many important aspects of the experimental observations on this system are not understood. Particularly intriguing is the hysteresis features in the response of the current density-voltage ( V J − ) curves [10][11][12][13] that have been related to a number of different explanations, as ferroelectric properties of the perovskite materials, [14][15][16] delayed electronic trapping processes, [17] or slow ion migration. [11,18,19] The recognition that the solar cell performance is heavily affected by time scale of the measurement and preconditioning procedures [9,17,20,21] has raised many concerns about the stability of the device and reliability for long time operation.…”