Ultrafast Photoconductivity and Terahertz Vibrational Dynamics in Double‐Helix SnIP Nanowires. Issue 34 (19th July 2021)

• Record Type: Journal Article
• Authors: Purschke, David N.; Pielmeier, Markus R. P.; Üzer, Ebru; Ott, Claudia; Jensen, Charles; Degg, Annabelle; Vogel, Anna; Amer, Naaman; Nilges, Tom; Hegmann, Frank A.
• Is Part Of: Advanced materials. Volume 33:Issue 34(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-07-19
• Subjects: double‐helix nanowires -- inorganic semiconductors -- photoconductivity -- photophysics -- terahertz vibrational dynamics -- ultrafast processes -- van der Waals materials; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202100978
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Tin iodide phosphide (SnIP), an inorganic double‐helix material, is a quasi‐1D van der Waals semiconductor that shows promise in photocatalysis and flexible electronics. However, the understanding of the fundamental photophysics and charge transport dynamics of this new material is limited. Here, time‐resolved terahertz (THz) spectroscopy is used to probe the transient photoconductivity of SnIP nanowire films and measure the carrier mobility. With insight into the highly anisotropic electronic structure from quantum chemical calculations, an electron mobility as high as 280 cm 2 V −1 s −1 along the double‐helix axis and a hole mobility of 238 cm 2 V −1 s −1 perpendicular to the double‐helix axis are detected. Additionally, infrared‐active (IR‐active) THz vibrational modes are measured, which shows excellent agreement with first‐principles calculations, and an ultrafast photoexcitation‐induced charge redistribution is observed that reduces the amplitude of a twisting mode of the outer SnI helix on picosecond timescales. Finally, it is shown that the carrier lifetime and mobility are limited by a trap density greater than 10 18 cm −3 . The results provide insight into the optical excitation and relaxation pathways of SnIP and demonstrate a remarkably high carrier mobility for such a soft and flexible material, suggesting that it could be ideally suited for flexible electronics applications. Abstract : The ultrafast optoelectronic properties of double‐helix tin iodide phosphide (SnIP) nanowires are explored using time‐resolved terahertz spectroscopy and quantum‐chemical calculations, providing deep insight into their photophysics, carrier dynamics, and anisotropic electronic structure. The carrier mobility is shown to be remarkably high for such a flexible and ultrasoft material, revealing the potential for future applications of SnIP in flexible electronics.