Phonon-Mediated Slow Hot Carrier Dynamics in Lead-Free Cs 3 Bi 2 I 9 Perovskite Single Crystal

ACS Appl. Electron. Mater.

Ghosh

Afroz

et al. 2022

Self Cite

Despite the high performance of lead-halide perovskite-based X-ray detectors, the toxicity and instability of lead require the development of lead-free perovskites for X-ray detection applications. Here, we demonstrate lead-free and environmentally friendly, all-inorganic millimeter-sized Cs2AgBiCl6 double perovskite single crystal (SC) for X-ray detection and imaging. The high dark resistivity (3.1 × 1010 Ω cm), high carrier mobility-lifetime product (5.36 × 10–4 cm2 V–1), and lower trap density (1.18 × 109 cm–3) in these double perovskite SCs render them a potential material for X-ray detection. The fabricated vertical structured X-ray detector exhibits a sensitivity of 325.78 μC Gy air–1 cm–2 and a limit of detection of 241 nGy s–1. Additionally, the Cs2AgBiCl6 SCs exhibit self-powered X-ray detection at zero bias with a sensitivity of 7 μC Gy air–1 cm–2. Moreover, the fabricated perovskite X-ray detector exhibits a stable and robust performance under continuous X-ray irradiation and long-term ambient storage. Further, we demonstrated the imaging capability of the Cs2AgBiCl6 X-ray detector using a metal test object and obtained a distortion-free image. Our findings demonstrate that the Cs2AgBiCl6 single crystal-based X-ray detectors have great potential as practical X-ray detectors and imaging for medical radiography.

Section: Methodsmentioning

confidence: 99%

Self-Powered X-ray Detection and Imaging using Cs₂AgBiCl₆ Lead-Free Double Perovskite Single Crystal

ACS Appl. Electron. Mater.

Ghosh

Afroz

et al. 2022

Self Cite

“…Metal halide perovskites are widely explored in photodetection applications. ,− The charge carrier generation under illumination leads to positive photoconductivity in these materials. A lot of reports demonstrate the PPC in perovskite materials. − Recently, the NPC was reported in halide perovskites under certain conditions. − In this line, Yuan et al presented the NPC under illumination in Cs 4 PbBr 6 perovskite single crystals .…”

mentioning

confidence: 99%

Negative Photoconductivity: Bizarre Physics in Semiconductors

Aranda

Saliba

et al. 2022

ACS Materials Lett.

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Many gadgets in our daily life work on the photodetection principle. These photodetectors (such as silicon (Si), gallium arsenide (GaAs), and indium gallium arsenide (InGaAs)) work on the principle of positive photoconductivity (PPC), where conductivity increases with light illumination. However, an opposite phenomenon, where the conductivity decreases with light exposure, also known as negative photoconductivity (NPC), has been reported in various inorganic (doped-Si, PbTe, 2D materials), organic (graphene, carbon nanotubes), and organic–inorganic hybrid (halide perovskites) materials. The origin of NPC phenomena in a semiconductor is still debated though its application potential has recently reached far beyond photodetection. Here, we have critically analyzed the fundamental photophysics of NPC phenomena in semiconductors, discussed its mechanistic origin in detail, and demonstrated how it depends on various external factors, such as temperature, illumination intensity, humidity, doping concentration, etc. We also highlight the recent progress of NPC in ultrasensitive detection applications. Finally, we discussed the existing challenges and provided a roadmap about how NPC can be helpful in next-generation semiconductor optoelectronics.

“…However, the toxicity of lead and poor environmental stability of these lead halide PSCs hinder their applications in commercialization. As an alternative to lead, lead-free PSCs are emerging now in optoelectronics applications. − Therefore, the study of anisotropic responses in lead-free PSCs should be promoted largely as they are rising potential materials in the field of detection. In this article, we have focused our discussion on the structural, optical, and electrical anisotropy of PSCs. Besides, PSCs should exhibit anisotropy in their mechanical, thermal, and magnetic properties. − Magneto-optical experiments will be useful to probe the anisotropic electron–hole interactions and reveal the magnetic properties along different facets.…”

Section: Future Outlook and Conclusionmentioning

confidence: 99%

Section: Future Outlook and Conclusionmentioning

confidence: 99%

Anisotropy in Perovskite Single Crystals: From Fundamentals to Applications

Satapathi

2022

J. Phys. Chem. C

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Single crystals of semiconductor materials have been extensively studied in optoelectronic applications because of the absence of grain boundary, lesser defects, and long-range order of crystallinity. Due to their multifaceted character, crystals are very often found to have significant anisotropic properties. These anisotropic properties lead to a considerable variation in their fundamental properties and optoelectronics applications. In the past decade, halide perovskites have emerged as one of the most exciting classes of semiconductors due to their rich photophysical properties leading to applications in solar cells, light-emitting diodes, photodetectors, etc. Especially, perovskite single crystals (PSCs) with an absence of grain boundaries, remarkably longer carrier diffusion lengths, significantly lower trap densities, and longrange order have received wide attention in large-scale device deployment. Interestingly, PSCs also exhibit strong anisotropy-dependent fundamental properties, and correspondingly their device applications are highly tunable. Here, in this feature article, we address a molecular perspective focusing on the structural, optical, and electronic anisotropy in PSCs. In addition, we discuss how anisotropy can affect the performance of PSCs-based devices. Furthermore, we highlight the future directions for implementing a fundamental understanding of the anisotropic response of PSCs to design novel and emergent optoelectronics devices.