Li@C₆₀ thin films: characterization and nonlinear optical properties

Organic materials have attracted considerable attention in nonlinear optical (NLO) applications as they have several advantages over inorganic materials, including high NLO response, and fast response time as well as low-cost and easy fabrication. Lithium-containing C₆₀ (Li@C₆₀) is promising for NLO over other organic materials because of its strong NLO response proven by theoretical and experimental studies. However, the low purity of Li@C₆₀ has been a bottleneck for applications in the fields of solar cells, electronics and optics. In 2010, highly purified Li@C₆₀ was finally obtained, encouraging further studies. In this study, we demonstrate a facile method to fabricate thin films of Li@C₆₀ and their strong NLO potential for high harmonic generation by showing its comparatively strong emission of degenerate-six-wave mixing, a fifth-order NLO effect.