Enhanced X-ray Detection of One-Dimensional DABCO-NH4I3 Perovskites via Anisotropic Carrier Transmission Study

Abstract

Metal-free perovskites exhibit significant potential for wearable X-ray detectors due to the non-toxic nature, degradability, aqueous solution processability and superior optoelectronic properties. DABCO-NH4I3 (DABCO denoted as N-N’-diazabicyclo[2.2.2]octonium), is a promising metal-free perovskite for the advantages of reduced exciton binding energy, enhanced mobility-lifetime product and superior absorption coefficients. However, the undesirable X-ray detecting performance of the device restricts its application. Reducing the dimensions of perovskite materials and adjusting crystal orientation are effective methods for improving optoelectronic properties and enhancing detection performance. Herein, high quality one-dimensional DABCO-NH4I3 single crystal is synthesized and in contrast to the conventional X-ray photoconductivity fitting approach, the time-of-flight (TOF) method using alpha particle-induced pulses is first employed to study the differences in single carrier transport performance between the [001] and [010] directions. The fitting results show that the hole mobility-lifetime product (μτ) for the [001] and [010] directions are 1.1×10-3 cm2 V-1 and 2.9×10-4 cm2 V-1, hole mobilities (μ) of 55.53 cm2 V-1s-1 and 4.63 cm2 V-1s-1, respectively. Furthermore, X-ray response results demonstrate a higher sensitivity of 62.1 μC Gy-1 cm-2 with a lower detection limit of 0.16 μGy s-1 for the [001] direction at 70V (sensitivity of 9.2 μC Gy-1 cm-2 with a detection limit of 0.16 μGy s-1 is for [010] direction). Hence, enhanced performances are successfully obtained by investigating the transport anisotropy of DABCO-NH4I3 perovskite which also provides a feasible route to improve the detecting performance of metal-free perovskites and promote its application.