Application Of Quantum Dot Photoluminescence In Solar Cell Efficiency Improvement

As conventional energy resources are close to exhaustion and environmental pressure is increasing, many countries are making great efforts to develop and exploit new energy resources which are one of the five most crucial technical fields. Photovoltaic power generation is a significant aspect of all the new energy resources. How to improve the photoelectric conversion efficiency of solar cells is always an important issue around the world.With the rapid development of science and technology, novel nano materials are gradually representing extraordinary prospects, especially in the research of new energy resources. Solar cells which are completely based on nano structure would become a breakthrough of solving the problem of energy shortage. In this thesis, Mn doped ZnSe (Mn:ZnSe) quantum dots and silicon quantum dots are investigated as photoluminescence(PL) converters on solar cells to carry out researches on improving the efficiency of solar cells.The Mn:ZnSe quantum dots used in this work have large stokes shift, absorb UV light and emit orange-yellow light at the same time. The properties of Mn:ZnSe quantum dots including absorption spectrum, emission spectrum and TEM image are characterized.In order to spin the quantum dots onto the surface of solar cells, we have chosen Poly Lauryl Methacrylate (PLMA) which is mixed with Mn:ZnSe quantum dots to produce the PL conversion film. We have proved that the film reserves the PL property of the quantum dots by exposing the film under UV light.We then studied the application of the Mn:ZnSe quantum dots as photoluminescence converters on c-Si solar cells. The response to UV light of solar cells and the photoelectric conversion efficiency are measured. Short-circuit current of solar cells under four monochromatic light—UV light (λ=325nm), blue light (λ=473nm), red light (λ=650nm) and IR light (λ=980nm) and their corresponding reflective spectrum are measured, proving that PL conversion does make contributions in the process. In addition, the Mn:ZnSe quantum dots were applied to solar cells under the irradiation of AMO solar simulator. It is found that the photoelectric conversion efficiency increases from12.54%to13.24%.After that, we measured the external quantum efficiency of solar cells and again prove the existence of PL conversion. What’s more, we calculated the theoretical value of the improvement of efficiency and quantified the percentage of improvement which derives from PL conversion.Finally, we fabricated silicon nanocrystal PL film and applied it to solar cells. The short-circuit current and I-V characteristic curve of solar cells are measured as well. The experiment results show that the performance of Mn:ZnSe quantum dot on improving the efficiency of solar cells is better than that of silicon nanocrystals.