Direct Synthesis of Selenium Nanowire Mesh on a Solid Substrate and Insights into Ultrafast Photocarrier Dynamics

Abstract

Selenium (Se) nanowires have generated much interest both for the fundamental understanding of crystal formation and growth and for technological applications in optoelectronics, imaging, piezoelectricity, catalysis, and energy harvesting and storage. Several methods have been established to synthesize Se nanowires, but they require sophisticated fabrication steps, are energy intensive, and may involve complex chemical reactions. Moreover, despite an increasing interest, little is known regarding photocarrier dynamics of Se nanowires. Here, we investigate a solution-based approach for the facile synthesis of single-crystal Se nanowires over the large scale where nanowires are directly grown from an amorphous bulk in a solution at room temperature without any chemical reaction. We study the nanowire nucleation and growth mechanism via electron microscopy. We also investigate, for the first time, the charge carrier dynamics and mobility of Se nanowire meshes by means of ultrafast transient absorption spectroscopy, nanosecond flash photolysis, and time-resolved terahertz spectroscopy. These contact-free and noninvasive approaches reveal a lifetime on the picosecond scale for free carriers and on the microsecond scale for trapped carriers, both of which are limited by trap-assisted recombination and a free carrier mobility of ∼3.0 cm 2 V −1 s −1. Our work for the first time reveals the rationale behind the excellent properties of some Se NW-based optoelectronic devices. It also highlights the simplicity and robustness of the novel Se nanowire synthesis scheme and paves the way toward the simple fabrication of advanced nanowire-based electronic and optoelectronic nanodevices.

Recent Progress and Perspectives of Thermally Drawn Multimaterial Fiber Electronics

“…This is beneficial for the use of Se nanowires in optoelectronic devices and is at the heart of the fiber-integrated device performance. [83] This work also reveals that the method for single crystal nanowire integration in the fiber platform can be This article is protected by copyright. All rights reserved.…”

“…Recently, Yan et al [41,82] In order to further understand the outstanding optoelectronic performance of devices, the charge carrier dynamics and mobility of the Se nanowire meshes were investigated by means of ultrafast transient absorption spectroscopy, nanosecond flash photolysis and time-resolved terahertz spectroscopy. [83] These contact-free and non-invasive approaches revealed a lifetime on the picosecond scale for free carriers and on the microsecond scale for trapped carriers (both of which are limited by trap-assisted recombination) and a free carrier mobility of ~3.0 cm 2 V -1 s -1 . The recovery time on the picosecond time scale of free carriers is attributed to ultrafast trapping of carriers mediated by surface states of each individual nanowire and contacts between nanowires because of the large surface to volume ratio of these randomly arranged wires.…”

“…This is beneficial for the use of Se nanowires in optoelectronic devices and is at the heart of the fiber-integrated device performance. [83] This work also reveals that the method for single crystal nanowire integration in the fiber platform can be extended to anisotropic fiber materials such as Te and Se/Te compound [84] that can be dissolved in corresponding solvents to exhibit an enhanced anisotropy of interfacial energy.…”

“…In order to further understand the outstanding optoelectronic performance of devices, the charge carrier dynamics and mobility of the Se nanowire meshes were investigated by means of ultrafast transient absorption spectroscopy, nanosecond flash photolysis, and time‐resolved terahertz spectroscopy . These contact‐free and noninvasive approaches revealed a lifetime on the picosecond scale for free carriers and on the microsecond scale for trapped carriers (both of which are limited by trap‐assisted recombination) and a free carrier mobility of ≈3.0 cm 2 V −1 s −1 .…”

Microstructured multimaterial fibers for efficient optical detection

“…It is necessary to note that the optoelectronic performance of the fiber can be further improved via controllable crystallization of the amorphous semiconductors. This is because that amorphous semiconductors generally have a high density of shallow and deep traps in the energy gap that may deteriorate the photosensitivity, rise and decay time, etc 28,29 …”