Fabrication and Characterization of a Photodiode Based on 5′,5′′-dibromo-o-cresolsulfophthalein (BCP)

5 ',5 ''-dibromo-o-cresolsulfophthalein (BCP) films were deposited on glass, quartz, and n-Si substrates by using conventional thermal evaporation method. XRD studies showed that the BCP has a polycrystalline structure in powder form and a nanocrystalline structure in thin film form. The nanostructure character of BCP films is confirmed by using a high-resolution transmission electron microscope (HRTEM). Thermal stability and phase change were examined by means of thermogravimetric analysis (TGA) and the differential scanning calorimetry (DSC), respectively. Optical absorption studies of BCP films were done in the wavelength range 200-2500 nm. The films showed a direct optical energy gap of 1.89 eV. Current versus voltage (I-V ) characteristics of Au/BCP/n-Si/Al were studied in darkness and in illumination modes. The device shows photoinduced charge transfer and can be used as a photodiode.