Integrating nanostructured electrodes in organic photovoltaic devices for enhancing near-infrared photoresponse

Abstract

We introduce a simple methodology to integrate prefabricated nanostructuredelectrodes in solution-processed organic photovoltaic (OPV) devices. The tailored "photonic electrode" nanostructure is used for light management in the device and for hole collection. This approach opens up new possibilities for designing photonically active structures that can enhance the absorption of sub-band gap photons in the active layer. We discuss the design, fabrication and characterization of photonic electrodes, and the methodology for integrating them to OPV devices using a simple lamination technique. We demonstrate theoretically and experimentally that OPV devices using photonic electrodes show a factor of ca. 5 enhancement in external quantum efficiency (EQE) in the near infrared region. We use simulations to trace the observed efficiency to surface plasmon polariton modes in the nanostructure.

Recent Advances of Plasmonic Organic Solar Cells: Photophysical Investigations

“…The light trapping and the optical field in the active layer are effectively intensified by the SPP mode issued by the Ag grating electrode in the OPV device. The spectral position of the simulated SPP mode agrees well with the measured EQE enhancement, demonstrating that the charge transfer states are photoinduced by the plasmatic trapping and can generate free carriers for charge collection when the nanograting is used as electrode [ 56 ].…”

“…In order to assess the SPP mode, the spectral reflectivity and absorption have been calculated with theoretical simulations based on the structure of P3HT:PCBM thin film on the metallic grating as electrode. In inverted solar cells with configurations of ITO/ZnO/P3HT:PCBM//P3HT:sorbitol/Ag grating/PET [ 72 ] and ITO/TiO 2 /P3HT:PCBM/PEDOT:PSS/Au grating [ 56 ], both SPP and photonic waveguide modes have been observed. The occurrence of the SPP or waveguide mode is essentially affected by the relative orientation of the incident light polarization to the grating lines.…”

“…In contrast, the waveguide mode can be detected under both TM and TE (i.e., in s-polarization, parallel to the grating lines) incident irradiations. Waveguide modes are not as readily observed as SPP, because they may be easily deteriorated by the small thickness of the organic solar cells [ 56 ]. The quantity of the waveguide modes increases with the thickness, whereas the SPP mode does not [ 81 ] (see Figure 13 ).…”

“… ( a ) Simulated absorbance spectra as a function of the incident light polarization relative to the grating period, for the active layer in a complete device stack incorporating the same Ag grating, with the corresponding absorbance for a device with a flat Ag electrode for comparison [ 56 ]; ( b ) the predicted polarization-dependent absorbance enhancement as a result of incorporating the nanostructured Ag grating electrode; ( c ) device EQE enhancement factor (see text for definition) for normal incidence with polarization parallel (TE; left) and perpendicular to the period of the grating (TM; right). Reflectivity measurements of inverted OSCs by illumination with TE (s-pol) ( d ) or TM (p-pol) [ 81 ].…”

Over 1000-fold enhancement of upconversion luminescence using water-dispersible metal-insulator-metal nanostructures

“…In this paper, we report over 1000-fold enhancement of NaYF 4 :Yb 3+ ,Er 3+ UCNPs incorporated in a metal–insulator–metal (MIM) nanostructure. The MIMs are fabricated using laser interference lithography, a scalable technique which results in a large area and high uniformity 32 , 33 , 42 – 45 . We first optimize the geometry to achieve resonance at 980 nm and thus maximize enhancement in absorption.…”