Plasmonic effects of Ag nanoparticles for absorption enhancement in polymer solar cells with MoO3 passivation layer

Abstract

In this work, we numerically demonstrate absorption enhancement in poly (3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and 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-C71-butyric acid methyl ester (PC70BM) based polymer solar cells (PSCs) by utilizing plasmonic effects of Ag nanoparticles (Ag NPs) incorporated at the interface between indium-tin-oxide (ITO) anode and an ultra-thin MoO3 anode buffer layer. The influence of factors such as particle size, spacing between neighboring particles, thickness of the active layer and the thickness of the MoO3 layer on the optical absorption enhancement has been investigated. Including 75 nm sized Ag NPs at the interface between ITO and 1 nm thick MoO3 layer resulted in 18.6% and 22.6% absorption enhancement in 80 nm thick P3HT:PCBM and PTB7:PC70BM active layers, respectively. PSCs have been fabricated using PTB7:PCBM as the active layer and 75 nm sized Ag NPs as the absorption enhancers for demonstrating performance enhancement. An improvement in device efficiency from 5.44% to 6.74% has been achieved by optimizing the number density of Ag NPs. Present study reveals that incorporating Ag NPs at the ITO/MoO3 interface is an effective approach to eliminate exciton quenching and charge carrier recombination problems while retaining most of the absorption enhancement induced by the Ag NPs.