First-principles modeling of organohalide thin films and interfaces

Organohalide perovskites have emerged as a class of materials with a unique combination of optoelectronic properties, suitable for a plethora of applications ranging from solar cells to photoelectrochemical tandem cells, to lasing and lighting. Theoretical and computational modeling can deliver an hitherto inaccessible atomistic view of the crucial material properties and heterointerfaces ruling the operational mechanisms in all these devices. Here we present a unified view of recent activity in the computational modeling of interfaces relevant to perovskites solar cells. The performance of the proposed simulation toolbox along with the fundamental modeling strategies are illustrated using selected examples of relevant materials and representative interfaces. In particular, we discuss interfaces between the prototype methylammonium lead iodide perovskite with TiO2 and ZnO semiconductors (acting as electron selective contacts in solar cells), exploring different surface terminations and doping by chloride ions. Also the effect of defects at the interface with TiO2 is analyzed and their impact on solar cell performance is discussed. Finally, the heterogeneous interface between methylammonium lead iodide and water is analyzed, revealing dynamical hints on the perovskite degradation by water.