Redox Shuttle-Based Electrolytes for Dye-Sensitized Solar Cells: Comprehensive Guidance, Recent Progress, and Future Perspective

Abstract

A redox electrolyte is a crucial part of dye-sensitized solar cells (DSSCs), which plays a significant role in the photovoltage and photocurrent of the DSSCs through efficient dye regeneration and minimization of charge recombination. An I–/I3 – redox shuttle has been mostly utilized, but it limits the open-circuit voltage (V oc) to 0.7–0.8 V. To improve the V oc value, an alternative redox shuttle with more positive redox potential is required. Thus, by utilizing cobalt complexes with polypyridyl ligands, a significant power conversion efficiency (PCE) of above 14% with a high V oc of up to 1 V under 1-sun illumination was achieved. Recently, the V oc of a DSSC has exceeded 1 V with a PCE of around 15% by using Cu-complex-based redox shuttles. The PCE of over 34% in DSSCs under ambient light by using these Cu-complex-based redox shuttles also proves the potential for the commercialization of DSSCs in indoor applications. However, most of the developed highly efficient porphyrin and organic dyes cannot be used for the Cu-complex-based redox shuttles due to their higher positive redox potentials. Therefore, the replacement of suitable ligands in Cu complexes or an alternative redox shuttle with a redox potential of 0.45–0.65 V has been required to utilize the highly efficient porphyrin and organic dyes. As a consequence, for the first time, the proposed strategy for a PCE enhancement of over 16% in DSSCs with a suitable redox shuttle is made by finding a superior counter electrode to enhance the fill factor and a suitable near-infrared (NIR)-absorbing dye for cosensitization with the existing dyes to further broaden the light absorption and enhance the short-circuit current density (J sc) value. This review comprehensively analyzes the redox shuttles and redox-shuttle-based liquid electrolytes for DSSCs and gives recent progress and perspectives.

Efficient Solar Cells Based on Porphyrin and Concerted Companion Dyes Featuring Benzo 12-Crown-4 for Suppressing Charge Recombination and Enhancing Dye Loading

“…Compared with porphyrin dye XW91 , CC dye XW92 exhibits further improved J SC (15.51 mA cm –2 ), V OC (880 mV) and PCE (10.4%). Interestingly, the J SC enhancement of XW92 relative to porphyrin dye XW91 based on the cobalt electrolyte outperforms that based on the iodine electrolyte, suggesting that the panchromatic absorption of CC dye may be promising in DSSCs based on a thinner photoanode like those using copper electrolytes and solid-state hole transport materials. , On this basis, XW92 was coadsorbed with CDCA using the Co 3+/2+ electrolyte. As a result, XW92 with 1.0 mM CDCA affords the highest PCE (11.0%), which is similar to the results obtained for the iodine-based DSSCs.…”

Review on Functional Electrolyte, Redox Polymers, and Solar Conversions in 3G Emerging Photovoltaic Technologies: Progress and Outlook

“…The redox potential can be calculated by the Nernst equation with reference to the normal hydrogen electrode (NHE). 65 =…”

High-Performance Carbon Black-Based Counter Electrodes for Copper (I)/(II)-Mediated Dye-Sensitized Solar Cells

“…8 In the past 30 years, several metal dyes, organic dyes, iodide, copper, and cobalt redox couples-based liquid electrolytes (LEs) have been developed for DSSCs to achieve high PCEs under different light conditions. 7,9,10 DSSCs have a higher PCE under ambient light than under sunlight. 11−15 Considering the various advantages of DSSCs, small and large-area module DSSCs have been fabricated for terrestrial power generation and powering portable electronics, respectively, especially for Internet of Things (IoT) devices.…”

“…DSSCs are generally fabricated using low-cost materials with colorful and decorative properties . In the past 30 years, several metal dyes, organic dyes, iodide, copper, and cobalt redox couples-based liquid electrolytes (LEs) have been developed for DSSCs to achieve high PCEs under different light conditions. ,, DSSCs have a higher PCE under ambient light than under sunlight. − Considering the various advantages of DSSCs, small and large-area module DSSCs have been fabricated for terrestrial power generation and powering portable electronics, respectively, especially for Internet of Things (IoT) devices. ,, DSSCs prepared using organic dyes and copper redox couples achieved high efficiencies of 15 and 37% under one-sun and room light conditions (7000 lx), respectively. , However, the leakage and evaporation of solvents especially at high temperatures lead to poor stability of DSSCs, thus still affecting the commercialization of these cells . To improve the stability without loss in the PCEs, polymer gel − anprintable electrolytes, , as well as solid-state redox electrolytes, , have been developed instead of LEs.…”