Minimizing structural deformation of gold nanorods in plasmon-enhanced dye-sensitized solar cells

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology 2017-11, Vol.19 (11), p.1-12, Article 365
• Main Authors: Törngren, Björn, Sandén, Simon, Nyman, Johan O., Tiihonen, Armi, Jiang, Hua, Ruokolainen, Janne, Halme, Janne, Österbacka, Ronald, Smått, Jan-Henrik
• Format: Article
• Language: English
• Subjects: Absorption; Absorption spectra; Aspect ratio; Characterization and Evaluation of Materials; Chemistry and Materials Science; Current efficiency; Deformation; Dye-sensitized solar cells; Dyes; Electromagnetic absorption; Gold; Inorganic Chemistry; Lasers; Low temperature; Materials Science; Maxima; Nanoparticles; Nanorods; Nanotechnology; Optical Devices; Optics; Performance enhancement; Photonics; Photovoltaic cells; Physical Chemistry; Red shift; Research Paper; Silica; Silicon dioxide; Solar cells; Titanium dioxide; Wavelengths
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-017-4062-9

Plasmonic metal nanoparticles have shown great promise in enhancing the light absorption of organic dyes and thus improving the performance of dye-sensitized solar cells (DSSCs). However, as the plasmon resonance of spherical nanoparticles is limited to a single wavelength maximum (e.g., ~ 520 nm for Au nanoparticles), we have here utilized silica-coated gold nanorods (Au@SiO 2 NRs) to improve the performance at higher wavelengths as well. By adjusting the aspect ratio of the Au@SiO 2 NRs, we can shift their absorption maxima to better match the absorption spectrum of the utilized dye (here we targeted the 600–800 nm range). The main challenge in utilizing anisotropic nanoparticles in DSSCs is their deformation during the heating step required to sinter the mesoporous TiO 2 photoanode and we show that the Au@SiO 2 NRs start to deform already at temperatures as low as 200 °C. In order to circumvent this problem, we incorporated the Au@SiO 2 NRs in a TiO 2 nanoparticle suspension that does not need high sintering temperatures to produce a functional photoanode. With various characterization methods, we observed that adding the plasmonic particles also affected the structure of the produced films. Nonetheless, utilizing this low-temperature processing protocol, we were able to minimize the structural deformation of the gold nanorods and preserve their characteristic plasmon peaks. This allowed us to see a clear redshift of the maximum in the incident photon-to-current efficiency spectra of the plasmonic devices (Δλ ~ 14 nm), which further proves the great potential of utilizing Au@SiO 2 NRs in DSSCs. Graphical Abstract Undeformed gold nanorods provide an enhanced performance of dye-sensitized solar cells at high wavelengths