International Journal of Hydrogen Energy, Vol.42, No.35, 22511-22517, 2017
Fine-tuning the fluorescent properties of Li and Na intercalated C-60 with hydrogen
In this work we demonstrate how hydrogen can be utilized to fine tune the emission gap of C-60 through the formation of direct C-H bonds in sodium and lithium intercalated systems (M6C60Hx). Upon hydrogenation, a shift in the emission spectrum to shorter wavelengths (higher energy) is observed relative to alkali metal free fulleranes (C60Hx) and pure C-60. This is attributed to the higher degree of hydrogenation of C-60 that can be achieved upon intercalation with alkali metals which increases the sp(3) hybridization of the system (decreases conjugation). Quantum yields of the sodium and lithium intercalated fulleranes are 1.3% and 1.8% respectively which are similar to those of alkali metal free fulleranes (1.4%). We also show that polymethyl methacrylate (PMMA) can be infused with the metal intercalated fulleranes to produce a fluorescent polymer with excellent transparency over the visible spectrum. This could potentially lead to further use of these materials in luminescent down shifting applications. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.