Variation in the Optical Properties of Carbon Dots Fabricated by a Green and Facile Strategy for Solar-Blind UV Detection

Abstract

Despite the strong light absorption and high efficiency of multiple carrier generation and collection of carbon dots (CDs), little attention has been paid to the field of photodetection. Herein, CDs are synthesized through a green and facile strategy, which only uses graphite rods and distilled water. It is found that the oxygen content and the optical properties of CDs could be modulated by the voltage applied between the two graphite rods. A series of tests reveal that the excitationindependent blue photoluminescence (PL) emission of as-prepared CDs is related to the topological defects. And the oxygencontaining groups would bring new energy levels between the band gaps of CDs, which enhanced the excitation-dependent yellowgreen PL emission and the absorption from the near-ultraviolet (UV) to the visible range. The CDs with fewer oxygen-containing groups show strong UV absorption and short cutoff wavelength, and they are utilized to fabricate solar-blind UV photodetectors. Tested under 254 nm UV illumination, the detectors exhibit a high photoresponsivity (1.14 mA/W) and highly characteristic wavelength-dependent response (R 254 /R 365 = 115). This study provides a deeper understanding of the relationships between optical properties and the structure/composition of CDs. More importantly, the solution processability of CDs paves the way for future high-performance, low-cost solar-blind photodetectors.

Hybridization state transition-driven carbon quantum dot (CQD)-based resistive switches for bionic synapses

“…1d). 27 O–H and O–C stretching vibrations are observed around 3400 cm −1 and 1600 cm −1 in its spectrum. This indicates that CQDs exhibit hydrophilicity due to their abundance of oxygen-containing functional groups.…”

Biopolymer-Mushroom Nanofiber Composite Xerogel Film: Bio-Base-Mediated Green, Chemically Resistant, Edible, and Printable Films

“…The characteristic absorption peak for both samples was observed near 3100–3400 cm –1 due to the O–H bond’s stretching vibration. The absorption peak near 1628 and 1650 cm –1 was observed for the BC and BCE CDs, due to the CO group stretching vibration . IR spectrum of BC at 2913 and 1028 cm –1 due to the C–H stretching (sp 3 ) and C–O stretching .…”

“…The absorption peak near 1628 and 1650 cm −1 was observed for the BC and BCE CDs, due to the C�O group stretching vibration. 47 IR spectrum of BC at 2913 and 1028 cm −1 due to the C−H stretching (sp 3 ) and C− O stretching. 48 A sharp peak was observed near 1366 cm −1 due to −CH 2 bending vibration.…”

A carbon conductive filament-induced robust resistance switching behavior for brain-inspired computing

“…1d), attributed to the CC transition. As the wavelength increases, a weaker shoulder appears around 305 nm caused by the electron transitions from n–π* of CO. 24 The designed memristor structure (Fig. 1e) is Pt/MoTe 2 /CQDs/ITO, in which ITO is chosen as the bottom electrode (BE), inert metal Pt as the top electrode (TE), and MoTe 2 /CQDs as the resistance switching layer.…”