Coupling between Ion Drift and Kinetics of Electronic Current Transients in MAPbBr3 Single Crystals

The optoelectronic properties of halide perovskite materials have fostered their utilization in many applications. Unravelling their working mechanisms remains challenging because of their mixed ionic-electronic conductive nature. By registering, with high reproducibility, the long-time current transients of a set of single-crystal methylammonium lead tribromide samples, the ion migration process was proved. Sample biasing experiments (ionic drift), with characteristic times exhibiting voltage dependence as proportional to V--(3/2), is interpreted with an ionic migration model obeying a ballistic-like voltage-dependent mobility (BVM) regime of space-charge-limited current. Ionic kinetics effectively modify the long-time electronic current, while the steady-state electronic currents' behavior is nearly ohmic. Using the ionic dynamic doping model (IDD) for the recovering current at zero bias (ion diffusion), the ionic mobility is estimated to be similar to 10(-6) cm(2) V-1 s(-1). Our findings suggest that ionic currents are negligible in comparison to the electronic currents; however, they influence them via changes in the charge density profile.

Automated summary

The optoelectronic properties of halide perovskite materials have been widely utilized, but understanding their working mechanisms is still challenging due to their mixed ionic-electronic conductive nature. By investigating the current transients of methylammonium lead tribromide samples, it was found that ion migration plays a significant role. The ionic migration model explains the voltage-dependent behavior observed in sample biasing experiments, while the steady-state electronic currents behave nearly ohmically. The estimated ionic mobility is approximately 10(-6) cm(2) V-1 s(-1).