Physical characteristics of naturally isolated high-purity curcumin and its application in photosensor appliances

•Naturally isolated high-purity curcumin (99.3%) from curcuma longa rhizomes.•Curcumin films with different thicknesses are prepared.•Ag/curcumin/p-Si/Al diode was fabricated.•The I-V characteristics curves of the diode in dark and under illumination were investigated.•The photoconduction, photosensitivity and the responsivity are determined. In this work, curcumin is naturally isolated from Curcuma longa rhizomes, and is carefully purified for the use in optoelectronic devices. Column chromatography technique is used to isolate curcumin with a purity of 99.3%. The molecular structure of curcumin is examined with the help of nuclear magnetic resonance (1H and 13C) and fourier transforms infrared. Curcumin is found to grow as crystals of monoclinic structure with space group P2. Curcumin films with thickness values between 40 and 120 nm are prepared with thermal evaporation technique. The optical properties of curcumin films are investigated. Curcumin film is used to fabricate Ag/curcumin/p-Si/Al diode. The current-voltage (I-V) characteristics curves of the diode in dark and under illumination conditions are investigated. The diode in dark shows a reasonable rectification behavior in which the basic diode parameters such as ideality factor, potential barrier height and series resistance are extracted. On illumination, the heterojunction diode is found to have a response to light intensity, from which the type of photoconduction, photosensitivity and the responsivity are determined.