2 research outputs found
Ternary Bulk Heterojunction Solar Cells: Addition of Soluble NIR Dyes for Photocurrent Generation beyond 800 nm
The
incorporation of a <i>tert</i>-butyl-functionalized silicon
2,3-naphthalocyanine bisÂ(trihexylsilyloxide) dye molecule as a third
component in a ternary blend bulk heterojunction (BHJ) organic solar
cell containing P3HT (donor) and PC<sub>60</sub>BM (acceptor) results
in increased NIR absorption. This absorption yields an increase of
up to 40% in the short-circuit current and up to 19% in the power
conversion efficiency (PCE) in photovoltaic devices. Two-dimensional
grazing incidence wide-angle X-ray scattering (2-D GIWAXS) experiments
show that compared to the unfunctionalized dye the <i>tert</i>-butyl functionalization enables an increase in the volume fraction
of the dye molecule that can be incorporated before the device performance
decreases. Quantum efficiency and absorption spectra also indicate
that, at dye concentrations above about 8 wt %, there is an approximately
30 nm red shift in the main silicon naphthalocyanine absorption peak,
allowing further dye addition to contribute to added photocurrent.
This peak shift is not observed in blends with unfunctionalized dye
molecules, however. This simple approach of using ternary blends may
be generally applicable for use in other unoptimized BHJ systems towards
increasing PCEs beyond current levels. Furthermore, this may offer
a new approach towards OPVs that absorb NIR photons without having
to design, synthesize, and purify complicated donor–acceptor
polymers
Hole Transport Materials with Low Glass Transition Temperatures and High Solubility for Application in Solid-State Dye-Sensitized Solar Cells
We present the synthesis and device characterization of new hole transport materials (HTMs) for application in solid-state dye-sensitized solar cells (ssDSSCs). In addition to possessing electrical properties well suited for ssDSSCs, these new HTMs have low glass transition temperatures, low melting points, and high solubility, which make them promising candidates for increased pore filling into mesoporous titania films. Using standard device fabrication methods and Z907 as the sensitizing dye, power conversion efficiencies (PCE) of 2.94% in 2-μm-thick cells were achieved, rivaling the PCE obtained by control devices using the state-of-the-art HTM spiro-OMeTAD. In 6-μm-thick cells, the device performance is shown to be higher than that obtained using spiro-OMeTAD, making these new HTMs promising for preparing high-efficiency ssDSSCs