Research Of Irradiation Effects On Silicon Solar Cells With Diode Laser

Compared with traditional methods of energy supply,there is a great possibility to get a more remarkable enhancement of conversion efficiency for laser power(of proper wavelength and intensity)beaming to solar cells.However,it should be noticed that cells may be damaged by high power laser.Based on the background,this thesis explored the performance of power supply by irradiating monocrystalline silicon solar cells with low power laser;as well as possible damage to the cells with high power laser.The main research has been done as follow:1.The properties of laser power(0.03~2.05 W/cm2)beaming to monocrystalline silicon solar cells were investigated.The experiment shows that the highest maximum output power(Pm)can be achieved with laser of 0.55 W/cm2,which,however,does not yield the highest short-circuit current(Isc)and fill factor(FF);the highest Isc could be gained in a relatively higher laser power density(0.68W/cm2)with IV curves seriously deteriorated.Fortunately,the deterioration does not continue if the laser irradiation was removed.Simulation reveals that the combination of temperature and series resistance is the main culprit of the short-circuit current's reduction.2.Irradiation effects of solar cells with high power laser were explored.Research shows that,for 30 seconds' irradiation,cell's performance would not be influenced significantly with laser of 5W/cm2,but reduced permanently when the laser power density is higher than 5.5W/cm2,and the higher laser power density,the more degradation.What's more,the degradation degree has a close relation with equilibrium temperature.The prolonged illumination would not bring about a more serious damage if the temperature had already reached a balanced point.3.Both minority-carrier lifetime and electroluminescence(EL)were measured for solar cells of various deterioration.Results show that minority-carrier lifetime,measured with open-circuit-voltage-decay method,remains almost the same for different areas in one cell,regardless of the phenonmenon that some area was damaged more seriously than others according to the apparent morphology.Minority-carrier lifetime could be enhanced under laser of 5W/cm2,and reduced when irradiated by laser of over 5.5W/cm2.For those solar cells with the similar IV curves,minority-carrier lifetime remains almost the same.Based on the images of electroluminescence,black spots could be found in the images after irradated by laser of over 5.5W/cm2,but,interestingly,pyrolysis product of rubber adhesive is totally invisible according to EL images.