Broadband EQE enhancement in organic solar cells with multiple-shaped silver nanoparticles: Optical coupling and interfacial engineering

A comprehensive study of the effect of interlayer with different shaped nanosphere, nanocube and nanoprism silver nanoparticles (Ag NPs) on the performance of organic solar cells (OSCs), based on the blend system of [poly [4,8-bis [(2-ethylhexyl) oxy] benzo [1,2-b: 4,5-b'] dithiophene-2,6-diyl] [3-fluoro-2[( 2-ethylhexyl)-carbonyl]-thieno-[3,4-b] thiophenediyl](PTB7):[[6,6]-phenyl-C-70-butyric acid methyl ester](PC70BM), was carried out. The results indicate that the OSCs having a combination of different shaped Ag NPs are more favorable for efficient light harvesting. The use of the mixed Ag NPs ethanol solution benefits the performance of the OSCs in two ways: (1) to enhance light absorption in the PTB7: PC70BM active layer through the coupling of localized surface plasmon resonance excited by different shaped Ag NPs, (2) to facilitate homogenous vertical phase separation favoring the exciton dissociation, charge transport and collection. The combination of these effects results in an average power conversion efficiency of 7.90%, which is higher than that of the optimized control cell (6.73%) made without Ag NPs. The results of this work provide a useful guidance for the development of high efficiency OSCs containing Ag NPs via solution fabrication route. (C) 2017 Elsevier Ltd. All rights reserved.