Theoretical And Experimental Research On Efficiency Improvements Of Laser Cells

Laser cell is a type of Photovoltaic cell or solar cell. Solar cell is illuminated by the wide spectrum sun light, while laser cell is irradiated by the narrow spectrum laser. Under the narrow-band illumination whose photon energy is near to the forbidden band width of the material of the laser cell, the laser cell would get relatively high spectral response.Laser cell has promising prospects in rapid charging, efficient electricity providing and laser wireless energy transmission, such as driving a small vehicle, small helicopter, implementing energy exchange between the targets. It is an ideal application in remote areas or disaster areas where continuous energy is needed. This technology can also be utilized in energy transmission of spacecraft to improve the performance and life of spacecraft.The photo-electric conversion efficiency of laser cell is the key of the total efficiency of laser wireless power transmission system. In order to obtain the high conversion efficiency, theoretical and experimental study of the conversion efficiency of laser cell was performed. The main works are listed below.1. The band theory of laser cell is analyzed. The influence of temperature and laser irradiation condition to the conversion efficiency is discussed. This thesis also establishes the single exponential model of laser cell. According to the single exponential model, the current-voltage characteristic function can be deduced to describe the operating state of the laser cell.2. The composition and influencing factors of laser cell output current are explored. In order to build relationship between the p-n junction parameters and external parameters of the laser cell, the formulas of photogeneration current, recombination current and diffusion current are deduced.3. In order to decrease the match loss between the laser spot and the laser cell, the circular laser cell is taken into account. The theoretical limit of conversion efficiency of the circular laser cell is simulated.4. An experiment platform was set up to measure the I-V curves of GaAs laser cell and Si laser under different laser irradiation conditions. The high photo-electric conversion efficiency of 50.33% was acquired under 2.48 W, 793 nm laser illumination.