The Study Of Polymer Solar Cells With Interface Modification Layer

ABSTRACT:The appropriate structure is critical for the performance of organic solar cells. In this thesis, we fabricated poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PCBM) bulk-heterojunction solar cell using vacuum evaporation and spin-coating technology. We demonstrated the improvement effect of organic small molecule (Liq, CuPc, and AlPcCl) buffer layer on the properties of the polymer solar cells, and discussed the mechanism underlying them.(1) By inserting a Liq thin layer between the active layer and Al cathode, the open circuit voltage (Voc), fill factor and power conversion efficiency (PCE) were improved. We attribute the improvement to the formation of dipole. Result from the reaction of Liq and Al, there are dipoles formed in the interface of Liq and Al. The dipoles made the interface ohmic contact, therefore, enhanced the electron extraction efficiency. (2) CuPc was introduced as anode buffer layer. It shows that the CuPc buffer layer can decrease the series resistance and increase the shunt resistance, thus lower the energy barrier, improve the properties of device. When CuPc used as cathode buffer layer, it can also decrease the series resistance, enhanced the Voc and PCE. (3) AlPcCl used as buffer layer between PEDOT:PSS and active layer, it caused the decline of the performance of device. The main reason is the lower HOMO of AlPcCl, blocking the hole transporting to anode. However, AlPcCl in cathode side, the short circuit current and PCE were improved. This can attribute to absorption enhancement in long wavelength.