Stable Cobalt-Mediated Monolithic Dye-Sensitized Solar Cells by Full Glass Encapsulation

Abstract

Dye-sensitized solar cells (DSSCs) emerged in the market as one of the most promising indoor photovoltaic technologies to address the need for wireless powering of low-consuming electronics and sensor nodes of the internet of things (IoT). The monolithic design structure of the cell (M-DSSCs) makes the devices simpler and cheaper, and it is straightforward for constructing in-series modules. The most efficient DSSCs reported so far are Co­(III/II)-mediated liquid junction cells with acetonitrile electrolytes; however, they are mostly unstable. This study reports on highly stable cobalt-mediated M-DSSCs, passing thermal cycling tests up to 85 °C according to ISOS standard protocols. Under 1000 h of aging in the dark and under simulated solar and artificial light soaking, all tested cells improved or retained their initial power conversion efficiency. Advanced long-term stability was achieved by eliminating the extrinsic factors of degradation, such as the interaction of the cell components with the environment and electrolyte leakage. This was obtained by encapsulation of the devices using a glass-frit sealant, including the holes for filling up the liquid components of the cells. The hermeticity of the encapsulation complies with the MIL-STD-883 standard fine helium gas leakage test, and its hermeticity remained unchanged after humidity–freeze cycles according to IEC 61646. The elimination of extrinsic degradation factors allowed reliable assessment of inner factors accountable for aging. The impact of the ISOS-protocol test conditions on the intrinsic device stability and long-term photovoltaic history of the M-DSSCs is discussed.

Ultralow Temperature Glass Frit Encapsulation for Stable Dye-Sensitized Solar Cells

“…34,48 Challenging stability issues arise when DSSCs use the highly volatile but so far the most efficient ACN-based electrolytes, particularly used with Co(III/II) redox shuttle; 21,22,49 extrinsic degradation factors must be eliminated and hermetic sealing becomes imperative for obtaining long-lasting devices. 44 Figure 9 shows the history of normalized photovoltaic metrics of cobalt-mediated DSSCs with ACN electrolyte, Y123 dye, and CE made from either PEDOT:PSS (S_YCoP configuration) or carbon (M_YCoC device); a batch of Surlyn-sealed cells (S_YCoP configuration) was also prepared for comparison. Tables S4−S6 present the detailed photovoltaic metrics of the devices.…”

“…Laser ablation by 355 nm nanosecond pulsed laser was used to drill the electrolyte injection holes in the CE substrate, as described elsewhere. 44 The FTO substrates were washed with detergent and distilled water in an ultrasonic bath. After drying, the substrates were treated for 10 min in an oxygen plasma (Diener Electronics cleaning station).…”

“…In all three types of devices, the PE substrates were 2.2 mm FTO-coated glasses (TEC7, GreatCell Solar) and the substrates for CE were 3 mm FTO-coated glasses (TEC8 GreatCell Solar). Laser ablation by 355 nm nanosecond pulsed laser was used to drill the electrolyte injection holes in the CE substrate, as described elsewhere . The FTO substrates were washed with detergent and distilled water in an ultrasonic bath.…”

Influence of Redox Couple on the Performance of ZnO Dye Solar Cells and Minimodules with Benzothiadiazole-Based Photosensitizers

“…Fully organic dyes are characterized by a high absorption coefficient, low production cost, and the possibility to change the absorption spectrum and HOMO/LUMO energy levels by incorporation of different electron donor and acceptor groups. Solar cell efficiencies above 10% have been achieved with DSSCs using purely organic dyes. , Various redox species such as coordination complexes of cobalt − and copper − have been proposed to replace the widely employed I – /I 3 – redox couple . The most important advantages include lower absorption, less corrosive nature, and moderate volatility .…”

“…Solar cell efficiencies above 10% have been achieved with DSSCs using purely organic dyes. 19 , 20 Various redox species such as coordination complexes of cobalt 21 − 31 and copper 32 − 37 have been proposed to replace the widely employed I – /I 3 – redox couple. 38 The most important advantages include lower absorption, less corrosive nature, and moderate volatility.…”