The Research On Surface Plasmon-enhanced Polymer Solar Cells

Compared with conventional inorganic semiconductor solar cells, the polymer solar cells have many advantages of light weight, good flexibility, low cost, and large scale manufacture process for organic/polymer materials. In particular, the large-area flexible devices can be obtained with an inexpensive printing process, thus the polymer solar cells are being one of the most promising photovoltaic devices. However, insufficient light absorption for employing only ~100 nm active layer thickness in polymer solar cells results in relatively low power conversion efficiency(PCE). Therefore, enhancing light absorption of the active layer is one of key points to improve the PCE. One of the effective approaches to promote absorption is utilizing surface plasmons, which has been widely applied in polymer solar cells in recent years.The size and shape of metal nanoparticles can influence the effect of the surface plasmons. At the same time, the location of the metal nanoparticles in the cells is also very important. In this thesis we have synthesized the Au nanoparticles with hexoctahedron shapes, and blended them into the anodic buffer layer to explore its influence on solar cell’s with P3HT:PC61BM. At the optimized blend ratio, the PCE increased from 2.81% to 3.34%. We have also obtained the Au nanocubes wrapped within ultrathin silica shells, and first introduced them into the active layer of solar cell with high performance PTB7:PC71BM bulk heterojunction, realizing an enhancement factor of as high as 24.97% in short circuit current density and as high as 22.76% in PCE. Based on the analysis, we found the strong localized surface plasmon resonance of Au nanocubes coated with silica acts directly on the photoactive layer, which greatly promoted the absorption of the active layer, thereby improving the short circuit current density effectively. As a result, the PCE has been also raised greatly.