Novel and highly stable indigo (C.I. Vat Blue I) organic semiconductor dye: Crystal structure, optically diffused reflectance and the electrical conductivity/dielectric behaviors

The design and characterization of indigo dye (C.I. Vat Blue I) have analyzed by several techniques such as XRD, FTIR; optically diffused reflectance based on the Kubelka–Munk model and electrical conductivity/dielectric properties that can use as natural organic semiconductor dyes. The XRD measurements revealed that the indigo dye has crystallized for the first time by using Crysfire and Check-cell assignment software in orthorhombic structure with a space group (P₂₂₂) and both the optimized lattice and refinement cell parameters have calculated before and after refinement. FTIR supports the fingerprint groups of indigo dye. Based on the Kubelka–Munk model, it has noted that there are two optical transition bands equal to 1.847 eV and 1.721 eV related to the multi-graded band gap of the indigo dye that enhanced the light absorption and can make the indigo material to be used in solar cell and optoelectronic applications. The AC/DC electrical conductivities as function frequency/temperatures, respectively, parallel/series dielectric properties (real/imaginary parts) have investigated and interpreted by using the two-probe electrical conductivity measurement. The AC conductivity and dielectric properties can support the charge-hopping carriers of barriers of various heights. Indigo dye is a highly stable organic dye for new organic devices and technologies.