Electronic conduction mechanism and optical spectroscopy of Indigo carmine as novel organic semiconductors A. Bouzidi 1,2 • I. S. Yahia 3,4 • W. Jilani 1,7 • S. M. El-Bashir 5,6 • S. AlFaify 3 • H. Algarni 3 • H. Guermazi 1 Received: 27 November 2017 / Accepted: 20 March 2018 Ó Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Indigo carmine (IC) is an organic material dye that can be used as an organic semiconductor. The IC powder pellet was characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy, AC\DC electric conductivity and optical diffused reflectance spectroscopy. The XRD measurements revealed that the IC powder is crys- tallized in triclinic system structure with the space group P 1 and both the optimized lattice and refinement cell parameters have calculated before and after refinement for the first time by using the program Crysfire and Checkcell software. The Kubelka–Munk model was used to determine the band gap energies of the IC powder pellet. Based on this model, the IC powder pellet presents two band gaps equal to 1.982 and 1.689 eV in the studied photon energy ranges. The first optical band gap (1.982 eV) is related to the basic HOMO–LUMO transition, and the other optical transition gap (1.689) is related to the trap inside the & A. Bouzidi abdelfattehbouzidi@yahoo.com & I. S. Yahia dr_isyahia@yahoo.com; isyahia@gmail.com; ihussein@kku.edu.sa 1 Research Unit, Physics of Insulating and Semi Insulating Materials, Faculty of Sciences, University of Sfax, B.P. 1171, 3000 Sfax, Tunisia 2 Technical and Vocational Training Corporation: Technical College Branch, P.O.B: 10, Ahad Rufidah 61974, Saudi Arabia 3 Advanced Functional Materials and Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha, Saudi Arabia 4 Nanoscience Laboratory for Environmental and Bio-medical Applications (NLEBA), Semiconductor Lab, Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo 11757, Egypt 5 Department of Physics, and Astronomy, Science College, King Saud University, Riyadh, Saudi Arabia 6 Department of Physics, Faculty of Science, Benha University, Banha, Egypt 7 Department of Physics, Zahran Al Janoob, Faculty of Science, King Khalid University, P.O. Box 9004, Abha, Saudi Arabia 123 Opt Quant Electron (2018) 50:176 https://doi.org/10.1007/s11082-018-1439-7