White‐Light Generation through Nonlinear Optical Response of 1,3,5,7‐Tetraphenyladamantane: Amorphous versus Crystalline States

The vast optical nonlinearity of 1,3,5,7‐tetraphenyladamantane (AdPh4) enables efficient frequency conversion. The observed spectrum depends heavily on the material's habitus. In particular, it shows nonlinear white‐light generation when its powder form is irradiated in the near‐infrared, similar to an analogous organotin sulfide cluster [(PhSn)4S6]. In contrast, single crystals of AdPh4 exclusively exhibit narrow‐band second‐harmonic generation, i.e., discrete conversion within the crystal, rather than spectrally broadband white‐light emission. This shows that crystallinity restricts the nonlinear response to the symmetry‐allowed higher‐harmonics, in this case the even‐numbered, second harmonic, and inhibits the quasi‐continuum white‐light emission. Using the diamondoid‐based material significantly enhances compatibility with conventional production techniques using photorefractive polymers and is thus an important step towards the fabrication of all‐integrated white‐light emitting devices. The vast nonlinear optical response of diamondoid‐based material 1,3,5,7‐tetraphenyladamantane is explored. In crystalline form, second‐harmonic generation is observed. In amorphous powder form, white‐light generation is the dominant response. The fully hydrocarbon‐based nature of this material paves the way for the development of doped polymers that can be used for frequency conversion.