Computationally Efficient DFT-Based Sampling of Ion Diffusion in Crystalline Solids.

We present a method for large-scale DFT-based screening of ion diffusion in crystalline solids. This is accomplished by extending the Ionic TuTraSt method to sample the potential energy surface by using single-point DFT calculations. To drastically reduce the number of single-point DFT calculations, symmetry, interpolation, and exclusion of high-energy regions are employed.

Room-Temperature Halide Perovskite Field-Effect Transistors by Ion Transport Mitigation.

Solution-processed halide perovskites have emerged as excellent optoelectronic materials for applications in photovoltaic solar cells and light-emitting diodes. However, the presence of mobile ions in the material hinders the development of perovskite field-effect transistors (FETs) due to screening of the gate potential in the nearby perovskite channel, and the resulting impediment to achieving gate modulation of an electronic current at room temperature. Here, room-temperature operation is demonstrated in cesium lead tribromide (CsPbBr ) perovskite-based FETs using an auxiliary ferroelectric gate of poly(vinylidenefluoride-co-trifluoroethylene) [P(VDF-TrFE)], to electrostatically fixate the mobile ions.

Delocalised kinetic Monte Carlo for simulating delocalisation-enhanced charge and exciton transport in disordered materials.

Charge transport is well understood in both highly ordered materials (band conduction) or highly disordered ones (hopping conduction). In moderately disordered materials-including many organic semiconductors-the approximations valid in either extreme break down, making it difficult to accurately model the conduction. In particular, describing wavefunction delocalisation requires a quantum treatment, which is difficult in disordered materials that lack periodicity.

3D-to-2D Transition of Anion Vacancy Mobility in CsPbBr under Hydrostatic Pressure.

Anion vacancy migration in the orthorhombic phase of the lead-halide perovskite CsPbBr under hydrostatic pressure is studied computationally. Density functional theory calculations are used to determine transition states, activation enthalpies, and attempt frequencies for vacancies to hop between nearby lattice sites, under pressure in the range 0.0-2.