Research On PTR Response And Lock-in Thermography For Characterization Of C-Si Solar Cell Irradiated By Charged Particles

In recent years, with the development of aerospace technology, the launch mission of space shuttle is dramatically increasing. Space solar cell, as the main energy supply system exposed in space environment, is bound to be irradiated by charged particles. The performance and efficiency of the space solar cell will be reduced by these particles. Thus it will affect the stability, reliability and service life of the space shuttle on-orbit. Therefore, it is important to look for accurate, nondestructive and efficient diagnosis techniques to evaluate the performance of the irradiation solar cells. Photothermal radiometry(PTR), as a new technique for nondestructive is employed for the evaluation of photoelectric performance for solar cell. In this work, the minority carrier transport process for solar cell is investigated and a one-dimensional mathematical model of thermal wave by modulated laser excitation is established. Moreover, the motion trials and energy loss of charged particles(i.e. electrons and protons) are simulated respectively. In addition, the PTR frequency response, scanning imaging and photothermal imaging experiments are studied for monocrystalline silicon(c-Si) solar cells irradiated by electrons and protons.The structure of solar cell is assumed as a 1D two layers pn abrupt junction and the minority carrier density wave model of solar cell is developed under modulated laser. The thermal wave model combined with the minority carrier density wave model of solar cell is established based on non-irradiation recombination process. The transport parameters(i.e. minority carrier lifetime, diffusion coefficient, and back surface recombination velocity) have been simulated to study the effects on amplitude-frequency response using the former model.The reason of irradiation damage for c-Si solar cell is carried out by Monte Carlo Simulation. The PTR frequency response experiments are used to study the effects of charged particles on the amplitude-frequency characteristics, and then the PTR mapping experiments are employed to research the effects of electron fluence on local inhomogeneity damage of electron irradiation c-Si solar cell.In the end of this work, the non-radiative recombination energy loss model of the solar cell is developed based on the principle of energy loss. The lock-in thermography experiments of the irradiation solar cell are used to obtain the electrical parameters and their distribution using the noncontact lock-in thermography system. The statistical method is employed for determination of the effects of irradiation damage on inhomogeneity characteristics of electrical parameters for c-Si solar cells irradiated by charged particles.