Abstract
Thin films of coumarin337 (C-337) dye were fabricated on n-type silicon (111) wafer using a high-vacuum thermal evaporation technique. Investigation of their structure using x-ray diffraction analysis and scanning electron microscopy revealed that the pristine C-337 films had sphere-shaped nanostructure. The absorbance, transmittance, and reflectance of the C-337 films were measured spectrophotometrically. Tauc's method revealed an indirect allowed-type optical transition for these films with an optical band gap of 1.59eV assisted by phonons of 52meV. Hybrid organic-inorganic heterojunction solar cells based on C-337 were deposited on n-type single-crystal silicon wafer. Many aspects of the electrical parameters of the Au/C-337/n-Si/Sb-Au heterojunction solar cells were studied under dark condition based on their capacitance-voltage, conductance-voltage, and current-voltage characteristics at different frequencies (100kHz to 1MHz). The Nyquist diagram of the solar cell was recorded at various frequencies. Furthermore, the illuminated current-voltage and phototransient characteristics of the cell were also measured and used to evaluate the photovoltaic performance of the device. Under illumination intensity of 90mW/cm(2), the solar cell showed good photovoltaic behavior with short-circuit current, open-circuit voltage, fill factor, and power conversion efficiency of 5.42mA, 0.55V, 0.59, and 4.39%, respectively. The photovoltaic and phototransient properties of the device indicate that it could be applied as both a solar cell and a linear dynamic rangeoptoelectronic switching sensor.