Investigation of transport properties of perovskite single crystals by pulsed and DC bias transient current technique

Abstract

Time of flight (ToF) transient current method is an important technique to study the transport characteristics of semiconductors. Here, both the (direct current) DC and pulse bias ToF transient current method were employed to investigate the transport properties and electric field distribution inside the MAPbI3 single crystal detector. Due to the almost homogeneous electric field built inside the detector during pulse bias ToF measurement, the free hole mobility can be directly calculated to be about 22 cm2V-1s-1, and the hole lifetime is around 6.5-17.5 μs. Hence, the mobility-lifetime product can be derived to be 1.4-3.9×10-4 cm2V-1. The transit time measured under the DC bias deviates with increasing voltage compared with that under the pulse bias, mainly arising from the inhomogeneous electric field distribution inside the perovskite. The positive space charge can then be deduced to increase from 3.1×1010 cm-3 to 6.89 ×1010 cm-3 in the bias range of 50-150 V. The ToF measurement can provide us a facile way to accurately measure the transport properties of the perovskite single crystals, and is helpful to obtain a rough picture of the internal electric field distribution as well.

Stable photocurrent–voltage characteristics of perovskite single crystal detectors obtained by pulsed bias

“…[18][19][20] Additionally, the combination of pulsed voltage and the time-of-flight method enables precise measurement of carrier mobility in perovskite SCs. [21,22] Take advantage of pulsed bias in inhibiting ion migration, minimal dark current drift can be achieved. [23] Nevertheless, it's rarely reported on pulsed bias to enhance the stability of photocurrent.…”