Large-Sized Nitrogen-Containing Biphenyl-Doped p-Terphenyl Crystals with Tunable Luminescence for Organic Scintillators

Large-sized organic crystals used as scintillators have great potential for X-ray detection and medical diagnosis due to their excellent environmental stability, extremely short fluorescence decay time, and low radiation detection limit. However, poor crystallinity, slow crystal growth speed, and lack of high-quality seed crystals make it challenging to obtain large sizes with high quality. Here, the vertical Bridgman method was introduced to grow organic doped crystals where p-terphenyl was used as the host and six nitrogenous biphenyls were adopted as the dopants. Nitrogen-containing biphenyl-doped p-terphenyl crystals were cultured to get the dimension of Φ 12 mm × 40 mm. Fluorescence spectra show that dopant molecules with molecular packing structures similar to those of the host molecule can achieve successful doping with the host molecule. Under X-ray excitation, the organic doped crystals exhibit tunable luminescence characteristics from blue light (465 nm) to green light (498 nm). Our research provides a reference for achieving successful doping of host and dopant molecules through molecular design.