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Dye-sensitized solar cells (DSSCs) are regarded as prospective solar cells for the next generation of photovoltaic technologies and have become research hotspots in the PV field. The counter electrode, as a crucial component of DSSCs, collects electrons from the external circuit and catalyzes the redox reduction in the electrolyte, which has a significant influence on the photovoltaic performance, long-term stability and cost of the devices. Solar cells, dye-sensitized solar cells, as well as the structure, principle, preparation and characterization of counter electrodes are mentioned in the introduction section. The next six sections discuss the counter electrodes based on transparency and flexibility, metals and alloys, carbon materials, conductive polymers, transition metal compounds, and hybrids, respectively. The special features and performance, advantages and disadvantages, preparation, characterization, mechanisms, important events and development histories of various counter electrodes are presented. In the eighth section, the development of counter electrodes is summarized with an outlook. This article panoramically reviews the counter electrodes in DSSCs, which is of great significance for enhancing the development levels of DSSCs and other photoelectrochemical devices.

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Dye-sensitized solar cells (DSSCs) have aroused intense interest over the past decade owing to their low cost and simple preparation procedures. Much effort has been devoted to the study of electrolytes that enable light-to-electrical power conversion for DSSC applications. This review focuses on recent progress in the field of liquid, solid-state, and quasi-solid-state electrolytes for DSSCs. It is believed that quasi-solid-state electrolytes, especially those utilizing thermosetting gels, are particularly applicable for fabricating high photoelectric performance and long-term stability of DSSCs in practical applications.

The development of perovskite solar cells has been faster than that of other photovoltaic cells, but their practical application is limited by further improvements in their performance and stability. A 3D/ 2D hybrid perovskite, combining the high efficiency of a 3D perovskite and the prominent stability of a 2D perovskite, is very promising. Herein, a strategy is designed by introducing 2-(2-pyridyl)ethylamine (2-PyEA) molecules with 2D structure and N atoms with a lone electron pair into perovskite. As an additive, 2-PyEA promotes the generation of 2D@3D perovskite; as a post-treated modifier, 2-PyEA facilitates the formation of 2D@3D/2D perovskite. The grain boundary and interface thus are dualoptimized in 2D@3D/2D perovskite by 2-PyEA. It is verified that defect density is reduced, residual stress is relieved, gradient energy is generated, charge transfer is improved, and carrier life is extended. Consequently, the dual-optimized PSC achieves a maximum power conversion efficiency of 23.2% with a negligible hysteresis and satisfactory stability, demonstrating a wonderful effect of 2-PyEA in forming efficient and stable PSCs.

applications in the fields of gas storage, electron conducting materials, catalysis, and sensors. [2] Nevertheless, the conductive and dielectric properties of pure MOF are too low to meet the requirement of electromagnetic (EM) impedance match. To improve the conductively and EM response capability, the thermal annealing of MOF precursors is the preferred strategy to gain the porous metal-carbonbased nanostructured materials. [3] More importantly, the final constituent of MOF derivatives can be effectively regulated by selecting the different metals sources and organic ligand. The MOF-derived hybrids can be consisted of magnetic metal oxide/ alloy, semiconductive carbon, or their composites via a facile subsequent treatment. Benefitting from the diversified composition and good chemical homogeneity, a number of efforts have been made to prove that MOFs are ideal templates or precursors for fabricating the versatile inorganic functional materials, such as graphitic carbon-encapsulated Ni nanoparticles, core-shell Fe/C nanocubes and CoSe@carbon nanoboxes. [2c,4] Based on these premises, it can be envisioned that MOF derivatives are promising and meaningful to fabricate the novel functional materials, especially in the microwave absorption (MA) field. Using a transformed strategy, MOF-derived magnetic-carbon composites can inherit the well-dispersed nanoparticles and the pristine microstructure with desirable properties.Nowadays, EM pollution issues have become increasingly serious due to the wide utilization in telecommunication, navigation, radar detector, and increasing number of electronic devices, which is an omnipresent problem that threatens our daily lives. [5] Therefore, EM absorption materials are crucial to the human protection and sophisticated equipment operation, having attracted the most extensive attention in past decades. To address these problems, searching for high-efficiency MA materials with a broadband absorption frequency and high loss capacity has stimulated huge interest in civil and military fields, especially in the gigahertz (GHz) band range. [6] It is known that the MA performance of absorbers is mainly determined by two Metal-organic framework (MOF) is highly desirable as a functional material owing to its low density, tunable pore size, and diversity of coordination formation, but limited by the poor dielectric properties. Herein, by controlling the solvent and mole ratio of cobalt/linker, multidimension-controllable MOF-derived nitrogen-doped carbon materials exhibit tunable morphology from sheet-, flower-, cube-, dodecahedron-to octahedron-like. Tunable electromagnetic parameters of Co@N-doped carbon composites (Co@NC)can be obtained and the initial MOF precursor determines the distribution of carbon framework and magnetic cobalt nanoparticles. Carbonized Co@NC compo sites possess the following advantages: i) controllable dimension and morphology to balance the electromagnetic properties with evenly charged density distribution; ii) magnetic-carbon composites offer plenty of inte...

Dye‐sensitized solar cells (DSSCs) are receiving considerable attention as low‐cost alternatives to conventional solar cells. In DSSCs based on liquid electrolytes, a photoelectric efficiency of 11 % has been achieved, but potential problems in sealing the cells and the low long‐term stability of these systems have impeded their practical use. Here, we present a thermoplastic gel electrolyte (TPGE) as an alternative to the liquid electrolytes used in DSSCs. The TPGE exhibits a thermoplastic character, high conductivity, long‐term stability, and can be prepared by a simple and convenient protocol. The viscosity, conductivity, and phase state of the TPGE can be controlled by tuning the composition. Using 40 wt % poly(ethylene glycol) (PEG) as the polymeric host, 60 wt % propylene carbonate (PC) as the solvent, and 0.65 M KI and 0.065 M I2 as the ionic conductors, a TPGE with a conductivity of 2.61 mS cm–2 is prepared. Based on this TPGE, a DSSC is fabricated with an overall light‐to‐electrical‐energy conversion efficiency of 7.22 % under 100 mW cm–2 irradiation. The present findings should accelerate the widespread use of DSSCs.

A high porous molybdenum sulfide-carbon (MoS 2 -C) hybrid film was prepared by using an in situ hydrothermal route. The MoS 2 -C hybrid film served as a low-cost and high efficient platinum-free counter electrode for a dye-sensitized solar cell (DSSC). The cyclic voltammetry, electrochemical impedance spectroscopy and Tafel curve analysis indicate that the MoS 2 -C electrode possesses low charge transfer resistance on the electrolyte-electrode interface, high electrocatalytic activity and fast reaction kinetics for the reduction of triiodide to iodide at the counter electrode, which is due to large specific surface area and special structure and compositions of MoS 2 -C film. A DSSC with the novel MoS 2 -C counter electrode achieve a high power conversion efficiency of 7.69% under standard light illumination, which exceeds that of the DSSC with a Pt counter electrode (6.74%).