Surface versus Bulk Currents and Ionic Space-Charge Effects in CsPbBr3 Single Crystals

CsPbBr3 single crystals have potential for application in ionizing-radiation detection devices due to their optimal optoelectronic properties. Yet, their mixed ionic-electronic conductivity produces instability and hysteretic artifacts hindering the long-term device operation. Herein, we report an electrical characterization of CsPbBr3 single crystals operating up to the time scale of hours. Our fast time-of-flight measurements reveal bulk mobilities of 13-26 cm(2) V-1 s(-1) with a negative voltage bias dependency. By means of a guard ring (GR) configuration, we separate bulk and surface mobilities showing significant qualitative and quantitative transport differences. Our experiments of current transients and impedance spectroscopy indicate the formation of several regimes of space-charge-limited current (SCLC) associated with mechanisms similar to the Poole-Frenkel ionized-trap-assisted transport. We show that the ionic-SCLC seems to be an operational mode in this lead halide perovskite, despite the fact that experiments can be designed where the contribution of mobile ions to transport is negligible.

Automated summary

CsPbBr3 single crystals with optimal optoelectronic properties have potential applications in ionizing-radiation detection devices. However, their mixed ionic-electronic conductivity leads to instability and hysteresis, which hinders long-term operation. Electrical characterization of CsPbBr3 single crystals reveals voltage bias-dependent bulk mobilities and qualitative and quantitative transport differences between bulk and surface mobilities. The formation of space-charge-limited current (SCLC) associated with mechanisms similar to Poole-Frenkel ionized-trap-assisted transport is observed.