Uncovering loss mechanisms in silver nanoparticle-blended plasmonic organic solar cells

Abstract

There has been much controversy over the incorporation of organic-ligand-encapsulated plasmonic nanoparticles in the active layer of bulk heterojunction organic solar cells, where both enhancement and detraction in performance have been reported. Here through comprehensive transient optical spectroscopy and electrical characterization, we demonstrate evidence of traps responsible for performance degradation in plasmonic organic solar cells fabricated with oleylamine-capped silver nanoparticles blended in the poly (3-hexylthiophene):[6,6]-phenyl-C 61-butyric acid methyl ester active layer. Despite an initial increase in exciton generation promoted by the presence of silver nanoparticles, transient absorption spectroscopy reveals no increase in the later free polaron population-attributed to fast trapping of polarons by nearby nanoparticles. The increased trap-assisted recombination is also reconfirmed by light intensity-dependent electrical measurements. These new insights into the photophysics and charge dynamics of plasmonic organic solar cells would resolve the existing controversy and provide clear guidelines for device design and fabrication.

A General Route to Enhance Polymer Solar Cell Performance using Plasmonic Nanoprisms

“…[ 8 ] However, incorporation of metal particles into the active layer can be problematic both because the particles can act as recombination centers, and, more generally, because the particles and their associated processing additives can also infl uence the notoriously sensitive morphology of an OPV bulk heterojunction. [ 9 ] nanoprisms can offer relatively larger scattering to absorption ratios than nanospheres, and possess much stronger optical antenna effects, with larger local fi eld enhancements. [ 15 ] Other potential advantages include the ability to more readily synthesize particles with strong plasmon resonances spanning from visible to NIR (Figure 1 C), and the fl at shapes of rod and prism-like particles that allow for a larger optical cross-section with a small thickness in the plane of the device to maximize optical interactions while minimizing the risk for shorting.…”

Tailoring Dispersion and Aggregation of Au Nanoparticles in the BHJ Layer of Polymer Solar Cells: Plasmon Effects versus Electrical Effects

“…Such a finding may be attributed to the good dispersity of Au NPs, which in turn results in weak light scattering due to small nanoparticles(< 20 nm). [14,28] Figure 2 b displays the optical scattered field distribution around the Au NPs at wavelengths of 500 and 600 nm when a 3D finite-differ- ence-time-domain (FDTD) simulation method was employed. These results show that the aggregated Au NPs have stronger field localization near the NP surface when compared to the individual Au NPs, which is in good agreement with the data shown in Figure 1 b.…”

“…However, the capping ligands on the metallic NPs may influence the morphological evolution of the BHJ active layer during the spin-coating process, which in turn has an effect on PSC performance. [14,15] Unfortunately, most of the published literature on metallic NPs embedded in the BHJ active layer does not include a quantitative description of the capping ligands on the metallic NPs. Furthermore, the capping ligands could be easily removed during washing after the synthesis step, which makes a quantitative analysis more difficult.…”

A Resonance‐Shifting Hybrid n‐Type Layer for Boosting Near‐Infrared Response in Highly Efficient Colloidal Quantum Dots Solar Cells

“…Intriguingly, exposing the Au@Ag NCs to the PbS enhanced the bimolecular recombination, presumably due to exciton quenching or carrier recombination on the Au@Ag NCs surface. [ 28 ] The FF dependence on the light intensity was also probed. As shown in Figure 4 c, the Au@Ag NCs-embedded device showed higher and fl atter FF responses as a function of light intensity, confi rming that the Au@Ag NCs-HL reduced carrier loss during the carrier transport and extraction.…”