Photonic Applications of Betanin

Betanin is the main betacyanin and major pigment extracted from red beets (Beta vulgaris). While its applications as food colorant, color-based sensors, antioxidant, anti-inflammatory, and antimicrobial traits are well-known, this natural dye is underestimated and underexploited in the field of light- and electric-responsive materials and devices. This comprehensive review describes the optical properties and molecular orbitals of this chromophore, along with its excited-state relaxation dynamics and emission quantum yields. Other relevant and basic behaviors of its excited-state features, such as cis-trans-photoisomerization, singlet-singlet energy transfer, photo-induced electron transfer, photosensitization of ¹O₂, and relative photo-instability are also presented in some relevant details. Photoconductive materials based on betanin and their related devices such as organic light emitting diodes, and dye-sensitized solar cells, are also surveyed. Other visible light-driven processes such as photodynamic processes and heterogeneous catalysis based on betanin-containing assembly/composites are demonstrated. Finally, the use of betanin as nonlinear optical materials is addressed.