Study of silicon solar cell at different intensities of illumination and wavelengths using impedance spectroscopy

The electrical properties of an n+–p–p+ structure-based single-crystalline silicon solar cell were studied by impedance spectroscopy, I–V and spectral response. The impedance spectrum is measured in dark, under different intensities (14, 43, 57, 71, 86, 100 mW/cm2) of illumination and wavelengths (400–1050 nm) of light. Under dark and at low intensities of illumination (<50 mW/cm2) the impedance spectra show perfect semicircles but at high intensities the semicircles are distorted at low frequencies. It is found that illumination provides an additional virtual R1C1 network parallel to the initial bulk RpCp network observed under dark conditions. The value of virtual resistance R1 depends on the illumination wavelength and shows an inverse relationship with the spectral response of the device.