Citation:
McCall, K. M. ; Liu, Z. ; Trimarchi, G. ; Stoumpos, C. C. ; Lin, W. ; He, Y. ; Hadar, I. ; Kanatzidis, M. G. ; Wessels, B. W. . Α-Particle Detection And Charge Transport Characteristics In The A3M2I9 Defect Perovskites (A = Cs, Rb; M = Bi, Sb). ACS PHOTONICS 2018, 5, 3748-3762.
Date Published:
SEPAbstract:
We have investigated the defect perovskites A3M2I9 (A = Cs, Rb; M = Bi, Sb) as materials for radiation detection. The phase purity of Bridgman-grown A3M2I9 single crystals was confirmed via high-resolution synchrotron X-ray diffraction, while density functional theory calculations (DFT) show surprisingly dispersive bands in the out-of-plane direction for these layered materials, with low effective masses for both holes and electrons. Accordingly, each of the four A3M2I9 defect perovskites showed response to 241Am α-particle irradiation for hole and electron electrode configurations, a remarkable ambipolar response that resembles the 3D halide perovskites. The electron response spectra were used to estimate the mobility–lifetime product (μτ)e for electrons in these materials, with Rb3Bi2I9 showing the lowest (μτ)e value of 1.7 × 10–6 cm2 V–1 and Cs3Bi2I9 the highest (μτ)e of 5.4 × 10–5 cm2 V–1. The rise time of the α-particle-generated pulse was used to estimate the electron mobility μe of the A3M2I9 defect perovskites, which ranged from 0.32 cm2 V–1s–1 for Rb3Sb2I9 to 4.3 cm2 V–1s–1 in Cs3Bi2I9. Similar analysis of the hole response spectra yielded (μτ)h values for each A3M2I9 compound, with Cs3Bi2I9 again showing the highest (μτ)h value of 1.8 × 10–5 cm2 V–1, while Rb3Bi2I9 showed the lowest (μτ)h with 2.0 × 10–6 cm2 V–1. Rise time analysis gave hole mobilities ranging from 1.7 cm2 V–1 s–1 for Cs3Bi2I9 to 0.14 cm2 V–1 s–1 for Cs3Sb2I9. Comparing the experimental electron and hole mobilities to the effective masses obtained from DFT calculations revealed sizable discrepancies, possibly indicating self-trapping of charge carriers due to electron–phonon interactions. The α-particle response of the A3M2I9 defect perovskites demonstrates their potential as semiconductor radiation detectors, with Cs3Bi2I9 and Cs3Sb2I9 showing the most promise.