Growth Regulation of Pentacene-Doped p-Terphenyl Crystals on Their Physical Properties for Promising Maser Gain Medium

Doped organic crystals possess wide application potential in the fields of scintillators and maser gain medium. However, the growth of doped organic single crystals with bulk size and high quality is still a big challenge due to the well-known poor crystallization capacity for organic materials. Here we report a thermal field-elevating technique to realize optimized growth conditions for organic crystals, where a pentacene-doped p-terphenyl single crystal with a size of Φ18 mm × 80 mm is obtained. Crystal quality and doping concentration effect on the optical properties of the crystalline wafers are investigated. The results show that p-terphenyl single crystal as an ordered matrix not only separates the guest molecules from one another to prevent quenching, but also constructs a Shpolskii-type host as an orienting medium to increase the interaction of pentacene with light. Moreover, a slightly reducing growth atmosphere is found to generate longer excitation lifetimes and a larger magnetic susceptibility...