Abstract
At this research study, we evaluate the performance of organic solar cells by adding a HMDS or OTS-based self-assembly-monolayer (SAM) on the ITO electrodes. Because HMDS and OTS are amphiphilic molecules, the hydrophilic end preferably bonds with ITO molecules whereas the hydrophobic end links to the pentacene, the host material of solar cells. Two positive effects were observed due to this surface treatment. First, deposited pentacene on the electrode surface had large grain size and less defects. Second, amphiphilic SAM can induce surface dipoles at the interface between ITO and pentacene, where the polarization direction is equivalent to the hole-current direction. It results in better hole extraction from the host materials. To verify the effect, we fabricated solar cells with a layer structure of ITO/SAM/pentacene/C60/BCP/Mg: Ag. Exposed to 2.5 times suns luminance, the SAM-coated solar cells was measured with parameters of Voc＝0.441±0.001 V, Jsc＝23.87±0.29 mA/cm2,Pmax＝2.977±0.040 mW/cm2,η＝1.19±0.01％, and FF＝28.27±0.08％. The overall performance was improved by 18.1%, compared with the cells without the SAM.