Long-Lived Afterglow from Elemental Sulfur Powder: Synergistic Effects of Impurity and Structure

Abstract

Elemental sulfur is not traditionally considered as an afterglow material, even though it can be endowed with fluorescence properties through processing it into nanodots. Herein, we discovered that elemental sulfur powder could emit room temperature phosphorescence (RTP) with a lifetime of 3.7 ms. A long-lived (>12 s) afterglow emission at 77 K could also be observed by the naked eye. Detailed investigations suggested that such a special phenomenon was attributed to impurity-related traps coupled with conduction and valence bands. After the sulfur is processed into nanodots, the rigid environment formed by the cross-linking of the surface ligands could stabilize the excited charges from quenching. This results in the promotion of RTP intensity and lifetime to achieve an emission lifetime of 200 ms. These results confirm the unique RTP of elemental sulfur powder, and also suggest the potential of sulfur-based materials as versatile components for the development of RTP materials.

Efficient Mechanochemical Conversion of Elemental Sulfur to Circularly Polarized Luminescent Sulfur Quantum Dots

“…The defect species is designated by vacancy sites or dangling bonds on the edge state of the sulfur core. − Additionally, the EPR spectrum of sulfur was recorded as a control (Figure S5). Generally, elemental sulfur is EPR active due to the presence of impurity-related traps …”

“…Generally, elemental sulfur is EPR active due to the presence of impurity-related traps. 36 Fourier transform infrared (FTIR) spectroscopy was recorded to elucidate surface functional groups and bonding characteristics of the L-Sdots (Figures S6 and S7 3a). 9 A distinct absorption peak at 285 nm is attributed to the n → π* transition of the sulfur atoms.…”