Study On Device Structure For The Optimization Of Polymer Solar Cells

Polymer solar cells (PSCs) have received considerable attention all over the world as an attractive alternative to silicon-based photovoltaic technology due to their unique advantages of low cost, light weight and potential application in flexible large-area devices. At present, compared with the continued development in photovoltaic materials there are slow development in device structures. As the improvement in carrier mobility and full-angle absorption is still a tough task in this kind of solar cells, it is an important topic to design effective and multi-purpose structures for the practical application. In this work, standard devices with regular structure were investigated comprehensive. Then the optical and electrical properties of the functional layers of PSCs were studied by theory analysis and experiments. Finally the wavy devices with surface relief gratings (SRGs) were manufactured and discussed.The fabrication technology of standard polymer solar cells were studied. As many special types of equipment are required during the fabrication of PSCs, this paper introduced an effective system according to the condition in our lab. Meanwhile, the whole preparation process including the fabrication of anode, cathode, active layer and buffer layer were presented and discussed. Some methods are also present to optimize performance of PSCs.The optical constants of active layer in the PSCs were key factors in the optical or structure simulation. Based on the spectra of transmittance, a photometric fitting method based on dispersion models was developed to determine the optical constants (including refractive index and extinction coefficient) and thickness of the active layer. The method will benefit the follow-up work of both the further research in PSCs and industrial manufacture. The effect of different optimization process was also included.Optical simulation was used to determine the SRGs'parameters before the experiments. Then the surface relief gratings were fabricated by a simple rubbing method in the PEDOT:PSS layer and the performances of such devices were tested and discussed. The optical constants were got by the transmittance fitting while RCWA method was used in the optical simulation to calculate the total absorption of the devices. Finally the devices were fabricated by the rubbing method. SRGs were successfully formed on the PEDOT:PSS layer, and were over printed on the photoactive layer and cathode consequently. The maximum increase of 27% in power conversion efficiency was achieved. Morphology and absorption of the devices were obtained by SEM, AFM and IPCE.