275813 Plasmonic Polymer Solar Cells with Spectrally Tuned Au/SiO2 Core/Shell Nanorods Incorporated in Active Layers

Thursday, November 1, 2012: 2:40 PM
Fayette (Westin )
Vladan Jankovic, Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA and Jane Chang, Chemical and Biomolecular Engineering, UCLA, Los Angeles, CA

Octadecyl tri-methoxysilane (OTMS) functionalized Au/SiO2 core/shell nanorods were incorporated into the active layers of two different polymer bulk heterojunction (BHJ) systems:  a broad band gap polymer (poly(3-hexylthiophene)(P3HT):[6,6]-phenyl-C61-butyric acid methyl ester(PCB60M)) and a low band gap polymer poly{2,6-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,4-b]dithiophene-alt-5-dibutyloctyl-3,6-bis(5-bromothiophen-2-yl) pyrrolo[3,4-c]pyrrole-1,4-dione} (PBDTT-DPP):PC60BM. The extinction peaks of the Au nanorod scattering centers was tuned to match the band edge of the two polymers by controlling their aspect ratio. For the P3HT:PC60BM system with a band edge around 700 nm, the addition of the core/shell nanorods of an aspect ratio 1:2.5 (resonant frequency peak is at around λ=650nm), resulted in 8% improvement in short circuit current (Jsc); for the low band gap polymer system PBDTT-DPP: PC60BM with band edge around 850 nm, we tuned the resonant frequency to near-infrared region by increasing the aspect ratio to 1:4 (resonant frequency peak is at around λ=800nm),  the addition of the core/shell nanorods resulted in 18% improvement in short circuit current (Jsc). The Jsc enhancement was consistent with external quantum efficiency (EQE) measurements and the EQE improvement factor matched the absorption resonance spectrum of Au/SiO2 nanorods in both systems. This work will instruct us on how to utilize and manipulate plasmon resonance of metallic nanoparticles to improve device efficiency in different polymer solar cell systems.

(a.) Photographic image Au nanosphere and 6 Au nanorod solutions, extinction spectra of Au nanosphere and 6 nanorod solutions and absorption spectra of two OPV polymers: PC3HT:PC6oBM and PBDTT-DPP:PCC60BM  (B.) TEM images of bare and silica coated Au nanorods with 650nm and 810nm resonances. The red shift in the peak plasmon resonance is due to the silica shell layer

(a) J-V measurement of PBTDD-DPP: PC60BM BHJ (Bulk heterojunction) solar cells with and without Au/SiO2 nanorods.  (b) External quantum efficiency(EQE) measurement of PBTDD-DPP:PC60BM BHJ (Bulk heterojunction) solar cells with and without Au/SiO2 nanorods. (c) EQE enhancement factor v.s. the plasmon resonance spectrum of Au/SiO2 nanorods (AR~1:4).


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