Transparent Conductive Oxide-Less Dye-Sensitized Solar Cells Consisting of Dye-Cocktail and Cobalt Based Redox Electrolyte

Abstract

Thin Ti-metal protected stainless steel metal mesh coated with mesoporous TiO2 as flexible photoanode has been used to fabricate back contact transparent conductive oxide-less dye-sensitized solar cells. TiO2 nanoparticle having a particle size of 15–20 nm sensitized with dye cocktail of two indoline dyes D-205 and D-131 were first utilized owing to their complementary light harvesting properties. Short-circuit photocurrent density (Jsc) for the dye cocktail combination of D-205 and D-131 (1:1) was found to be increased due to the increased photon harvesting in the 400–500 nm mainly associated with the contribution from D-131 dye. In addition, the electron recombination was suppressed when dye cocktail was employed as confirmed by the dark current measurement leading to higher open-circuit voltage (Voc). The enhanced Jsc accompanied with increased Voc resulted in to an improved efficiency of 3.59% for this cocktail combination. To enhance the efficiency even further, we have utilized TiO2 nanoparticle having a larger particle size of 30 nm facilitating the mass transport of the bulky [Co(bpy)3]3+/2+ redox species. In order to enhance the photon harvesting window TiO2 nanoparticles were sensitized with porphyrin dye (YD2-o-C8) along with different dye cocktail combinations with another complementary dye (Y123). Utilization of a dye cocktail of YD2-o-C8 and Y123 (4:1) led to improved photoconversion efficiency of 5.25% under simulated solar irradiation.

Solid‐State Monolithic Dye‐Sensitized Solar Cell Exceeding 10% Efficiency Using a Copper‐Complex Hole Transport Material and a Carbon Counter‐Electrode

“…Y123 dye shows a wide light absorption in the wavelength region of 400‐600 nm, with an absorption maximum (λ max ) at 482 nm, having a molar extinction coefficient ( ε ) of 55.2 × 10 3 M −1 cm −1 (Figure S3, Supporting Information), in agreement with previously reported ε . [ 30–33 ]…”

Optimization of Device Parameters for Back‐Contact Transparent Conductive Oxide–Less Dye‐Sensitized Solar Cells Fabrication

“…Here, to increase the PCE further, we employed dye cocktail of D205 and D131 dyes (1:1) because of their reciprocal optical absorption in the zone 400–500 nm. [ 26 ] The MP TiO 2 layer thickness (10 μm) and absorption time for dye (16 h) were kept the same in each case. For TCO‐less DSSCs, we employed porous PTFE film of 35 μm to hold the electrolyte layer between photoanode and counter electrode.…”

Boosting the Efficiency of Low-Cost T-C-O-Less Dye-Sensitized Solar Cells Employing Nanoparticle Spacers and Cobalt Complex Redox Shuttle

“…The printed TiO 2 layer thickness on the flexible SS-mesh with Ti–metal protection was 10 μm and kept the same for all the devices. The photovoltaic characteristics of T-C-O-less B-C-DSCs that utilize the dye mixture of Y123 and porphyrin (YD2-o-C8) dyes with a dye mixing ratio of (1:4) employing the Co­(bpy) 2+/3+ redox shuttle are demonstrated in Figure , and the related photovoltaic parameters are presented in Table . Here, we have utilized different nanoparticle spacers of TiO 2 (30, 20 nm) and ZrO 2 (15 nm) films of a 4 μm thick layer, which was maintained the same for all the devices to absorb the electrolyte layer coated on the Pt counter electrode.…”

“…The bare SS-mesh was protected from both sides with a thin-layer sputtering (CFS-4EP, Shibaura Mechatronics, Japan) of the Ti metal (240 nm) (Ti/SS-mesh) to suppress the back-electron reactions from the flexible photoelectrode. 31 The porous TiO 2 (30 nm) layer was screen-printed dyes with a dye mixing ratio of (1:4) 32 employing the Co(bpy) 2+/3+ redox shuttle are demonstrated in Figure 3, and the related photovoltaic parameters are presented in Table 1.…”