Ultra-Thin Organic Solar Cells Incorporating Dielectric-Coated Comb Silver Nanogratings

Abstract

Although coating engineering on metallic nanostructures has been frequently applied in organic solar cells (OSCs) for improving the device performance by preventing the possible exciton quenching and charge recombination at the metal surface, there have been few theoretical researches addressing how the dielectric-coating of metal nanostructures influences the optical performance of OSCs. Here, we theoretically investigate the effect of coating a comb silver nanograting by a dielectric film on the absorption performance of OSCs. It is found that, under transverse-magnetic (TM) polarization, when the refractive index or thickness of the dielectric-coating is tuned, different orders of plasmonic waveguide modes are excited by the P3HT:PC 61 BM/coating/Ag triple-layered system. The dispersion relationship of such a plamsonic waveguide mode is solved and analyzed for clarifying the physical mechanism of the induced light trapping effect. It shows that for optimizing the light absorption in active layer under TM polarization, it is more favorable to coat a thin dielectric film (of 1 nm thick) with a suitable refractive index. While under transverse-electric (TE) polarization, the higher refractive index of dielectric-coating, the better the effect of light trapping.

Plasmonically Enhanced Upconversion Luminescence via Holographically Formed Silver Nanogratings

“…Upon the TM-polarized incidence (polarization perpendicular to Ag nanograting lines), the absorption spectrum presents a narrow absorption band with a central wavelength of 447 nm, which is due to the LSPR of the Ag nanoparticles, ,, also a broadband absorption from 559 to 1400 nm, and the maximum absorption at 1134 nm under the incident light polarization parallel to grating structures. In contrast, upon the TE-polarized incidence (polarization parallel to Ag nanograting lines), the NIR broadband shows an abrupt decrease and the narrow absorption band of Ag grating also decreases slightly . It clearly shows that the Ag nanograting has much stronger absorption for the TM-polarized incidence compared to the TE-polarized case.…”

“…In contrast, upon the TE-polarized incidence (polarization parallel to Ag nanograting lines), the NIR broadband shows an abrupt decrease and the narrow absorption band of Ag grating also decreases slightly. 26 It clearly shows that the Ag nanograting has much stronger absorption for the TMpolarized incidence compared to the TE-polarized case. Figure 3b summarizes the measured absorption spectra for the Ag nanogratings with different periods and the Ag nanofilm under the TM-polarized incidence.…”

Comparison of Nanohole-Type and Nanopillar-Type Patterned Metallic Electrodes Incorporated in Organic Solar Cells

“…The wavelength-dependent refractive indices ( n ) of PSBTBT:PC 71 BM are obtained from [ 33 ]. And other refractive indices of the materials used in this work are extracted from [ 18 ] and [ 19 ]. The absorption efficiency of the active layer ( η ) and integrated absorption efficiency ( η I ) (over the wavelength range between 350 and 850 nm weighted by the AM1.5G spectrum) are calculated.…”

“…PMEs with one-dimensionally arrayed patterns [ 8 , 9 , 14 – 19 ] (i.e., 2D PMEs) can be easily fabricated based on the two-beam interference technique [ 20 ]; however, the absorption enhancement in OSCs is sensitive to polarization since plasmonic modes cannot be excited at the traverse electric (TE) polarized incidence [ 10 ]. PMEs with two-dimensionally (2D) arrayed patterns (i.e., 3D PMEs), which can boost light harvesting efficiency polarization insensitively, have been extensively investigated in the past few years [ 14 , 21 – 31 ].…”