Re-emerging photo responsiveness enhancement under compression in (NH4)2SeBr6

Abstract

Pressure has an essential role in the control of both the photo-responsive and electrical transport properties of halide perovskites. As a lead-free halide double perovskite material, (NH4)2SeBr6, which avoids the use of a toxic lead element, has become an ideal candidate for application in photovoltaic and photoelectric devices. In this paper, the photoelectric response and electrical transport response properties of (NH4)2SeBr6 have been studied by photocurrent and alternating current impedance spectroscopy measurements under high pressure up to 21.2 GPa, respectively. The current results indicate that in (NH4)2SeBr6, a second photo-responsiveness enhancement re-emerges above 11.2 GPa, after the photocurrent drops from the first maximum at 6.5 GPa and reaches the second maximum at 16.4 GPa. The photoelectric response of (NH4)2SeBr6 in phase II is better than that of phase I, and electron conduction rather than ion conduction plays a dominant role in the whole electrical transportation process under compression.