Predicted THz-wave absorption properties observed in all-inorganic perovskite CsPbI3 thin films: Integrity at the grain boundary

• Published in: Materials today physics Vol. 30; p. 100960
• Main Authors: Maeng, Inhee, Chen, Shi, Lee, Seungjun, Wang, Shenghao, Kwon, Young-Kyun, Jung, Min-Cherl
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2023
• Subjects: All-inorganic perovskite thin film; Clean grain boundary; Three major THz absorptions; THz-wave absorption; γ-CsPbI3; All-inorganic perovskite thin film; Three major THz absorptions; THz-wave absorption; Clean grain boundary; γ-CsPbI3
• ISSN: 2542-5293; 2542-5293
• DOI: 10.1016/j.mtphys.2022.100960

The realization of terahertz (THz) detectors using organic-inorganic hybrid perovskite (OHP) materials presents a challenge because of the high real conductivities and broad THz absorption spectra required. The control of phonon vibration modes in OHPs depends on the control of defect states such as the defect-incorporated perovskite structure and the δ/α-mixed interfacial structure observed in MAPbI3 and δ/α-mixed FAPbI3, respectively. Difficulties with defect control in particular materials may amplify relative risk factors and invite strong resistance to commercialization. As an alternative to OHPs, the all-inorganic perovskite material CsPbI3 (lacking the hydrophobic organic cations that generate structural defects) constitutes a good candidate for THz detectors. We investigated the phonon vibration modes of thin films of the all-inorganic perovskite γ-CsPbI3 containing no atomic or chemical defect states. We observed the three expected major phonon vibration modes at 0.9, 1.5, and 1.8 THz that originate from the transverse I–Pb–I frame, the Cs–I–Cs optical vibration, and the longitudinal I–Pb–I frame, respectively, finding good agreement with theoretical simulations. Significantly, the real conductivity of these all-inorganic perovskite thin films ranged from approximately 10–40 S/cm across a broad frequency range of 0.5–3.0 THz, demonstrating the material's considerable potential for application as a THz-band detector. [Display omitted] •Investigation of the phonon vibration modes of thin films of the all-inorganic perovskite γ-CsPbI3 containing no atomic or chemical defect states.•Observation of the three major phonon vibration modes at 0.9, 1.5, and 1.8 THz.•By theoretical calculation, the origins of 0.9 THz: Transverse I–Pb–I frame, 1.5 THz: Cs–I–Cs optical vibration, and 1.8 THz: the longitudinal I–Pb–I frame.•Large real conductivity (10–40 S/cm) and broad frequency range of THz absorption (0.5–3.0 THz): the material's considerable potential for application as a THz-band detector.