On the Role of PTB7-Th:[70]PCBM Blend Concentration in ortho-Xylene on Polymer Solar-Cell Performance

Low-band gap polymers as donors are the new approach to realize high efficiency polymer solar cells. Among them, PTB7-Th is one of the most promising candidates, thanks to the possibility of exploiting deposition protocols (technique, solvent, concentration) from the most-known PTB7, and demonstrating a power conversion efficiency exceeding 10%. In this paper, we focus on the role of the ink concentration for the film deposition and formation of the active layer. The effect of the solid content (PTB7-Th:[70]PCBM) in an ortho-xylene based solution on the polymer solar cell performance are investigated. Farther, a correlation between solid content and DIO additive in the ink formulation with respect to device performance is discussed. A remarkable PCE of 8.2% has been demonstrated.