High-Efficiency Bifacial Dye-Sensitized Solar Cells for Application under Indoor Light Conditions

Abstract

High-efficiency, stable bifacial dye-sensitized solar cells (DSSCs) are prepared for application under indoor light conditions. A 3-methoxypropionitrile solvent and cobalt redox couples are utilized to prepare the electrolytes. To obtain the best cell performance, the components of the DSSCs, including electrolytes, photoanodes, and counter electrodes (CEs), are regulated. The experimental results indicate that an electrolyte comprising a Co (II/III) ratio of 0.11/0.025 M, 1.2 M 4-tert-butylpyridine, Y123 dye, a CE with the platinum (Pt) layer thickness of 0.16 nm, and a photoanode with titanium dioxide (TiO2) layer thickness of 10 μm (6 μm main layer and 4 μm scattering layer) are the best conditions under which to achieve a high power conversion efficiency. It is also found that the best cells have high recombination resistance at the photoelectrode/electrolyte interface and low charge transfer resistance at the counter electrode/electrolyte interface, which contributes to, respectively, the high current density and open-circuit voltage of the corresponding cells. This DSSC can achieve efficiencies of 22.66%, 23.48%, and 24.52%, respectively, under T5 light illumination of 201.8, 607.8, and 999.6 lx. For fabrication of bifacial DSSCs with a semitransparent property, photoanodes without the TiO2 scattering layer, as well as an ultrathin Pt film, are utilized. The thicknesses of the TiO2 main layer and Pt film are reregulated. This shows that a Pt film with 0.55 nm thickness has both high transmittance (76.01%) and catalytic activity. By using an 8 μm TiO2 main layer, optimal cell efficiencies of 20.65% and 17.31% can be achieved, respectively, for the front-side and back-side illuminations of 200 lx T5 light. The cells are highly stable during a long-term performance test at both 35 and 50 °C.

The Performance‐Determining Role of Lewis Bases in Dye‐Sensitized Solar Cells Employing Copper‐Bisphenanthroline Redox Mediators

“…[ 2–4 ] DSCs are currently the most efficient solar cell technology in low light conditions, which makes them excellent candidates for building and automobile integrated photovoltaics and to power sensors, appliances for the Internet of Things (IoT), and portable devices. [ 5–10 ] Recent developments of new photoanodes, counter electrodes, dyes, and co‐adsorption strategies have further improved device efficiencies. [ 11–28 ] Furthermore, the improved stabilities and efficiencies of aqueous DSCs open up new opportunities for the sustainability of these devices.…”

Challenges and prospects of ambient hybrid solar cell applications

“…Venkatesan et al optimized the thickness of their platinum counter electrodes to allow for backside illumination. 41 Huang et al proposed a titanium foil as anode current collector instead of the traditional glass:conductive oxide design. 42 Kapil et al designed their entire DSC around a cylindrical titanium foil to allow for omnidirectional photon harvesting.…”

“… 61,62 One year later, Venkatesan et al achieved an open-circuit voltage of 850 mV and a conversion efficiency of 24.5% at 1000 lx. 41 In 2017, Freitag et al reported on the indoor performance of DSCs based on a copper complex-based redox electrolyte. Devices based on the Cu II/I (tmby) 2 (tmby = 4,4′,6,6′-tetramethyl-2,2′-bipyridine) redox couple (870 mV vs. NHE) achieved 28.9% power conversion efficiency at 1000 lx.…”

Solar Cells for Indoor Applications: Progress and Development

“…This phenomenon can improve the PCE of a DSSC in an indoor environment. Venkatesan and co-workers fabricated a highly efficient (PCE values of 22.66%, 23.48%, and 24.52% under illuminations of 201.8 lx, 607.8 lx, and 999.6 lx, respectively) bi-facial DSSC for indoor applications [ 94 ], using the Y123 dye as a sensitizer. Grätzel and co-workers fabricated a DSSC using XY1b/Y123 as a sensitizer, which exhibited a high PCE (32%) under the illumination of a 1000 lx Osram 930 warm white fluorescent lamp [ 78 ].…”