Plasmonic backscattering enhancement for inverted polymer solar cells

The enhanced performance of inverted polymer solar cells enabled by a plasmonic backscattering effect is reported upon. To produce localized surface plasmons (LSPs) at the rear anode, thermally deposited Ag nanoparticles (NPs) are embedded in the MoO ₃ hole extraction layer. Upon optimizing the MoO ₃/Ag NPs/MoO ₃ sandwich structure, enhanced light harvesting is achieved via plasmonic backscattering into the photoactive layer of poly(3-hexylthiophene)/[6,6]-phenyl-C61 butyric acid methyl ester (P3HT:PCBM), resulting in an increase in photocurrent without sacrificing electrical properties, and ∼20% enhancement in power conversion efficiency, of 4.32% vs. 3.61% of the reference device. The performance improvement of the inverted PSCs is ascribed to the enhanced light absorption as a result of the light backscattering as well as the excitation of LSPs induced by Ag NPs embedded in the MoO ₃ layer. The present method provides a promising pathway for the fabrication of high-efficiency PSCs in an inexpensive and scalable way.