Dye-sensitized solar cells (DSSCs) belong to the group of thin-film solar cells which have been under extensive research for more than two decades due to their low cost, simple preparation methodology, low toxicity and ease of production. Still, there is lot of scope for the replacement of current DSSC materials due to their high cost, less abundance, and long-term stability. The efficiency of existing DSSCs reaches up to 12%, using Ru(II) dyes by optimizing material and structural properties which is still less than the efficiency offered by first- and second-generation solar cells, i.e., other thin-film solar cells and Si-based solar cells which offer ~ 20–30% efficiency. This article provides an in-depth review on DSSC construction, operating principle, key problems (low efficiency, low scalability, and low stability), prospective efficient materials, and finally a brief insight to commercialization.

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Dye-Sensitized Solar Cells: Fundamentals and Current Status

As an emerging photovoltaic technology, dye-sensitized solar cells (DSSCs) have attracted a great deal of academic and industrial interest due to their reasonably high power conversion efficiency, low material cost and facile fabrication process. Metal-free organic dyes, as one of the key components of DSSCs, play a pivotal role in light harvesting and electron injection. Among the various species of organic dyes, easily tunable 10H-phenothiazine-based dyes hold a large proportion. The electron-rich nitrogen and sulfur atoms render 10H-phenothiazine a stronger donor character than other amines, even better than triphenylamine, tetrahydroquinoline, carbazole and iminodibenzyl. On the other hand, the unique non-planar butterfly conformation of the 10H-phenothiazine ring can sufficiently suppress molecular aggregation and the formation of excimers. The positions N-10, C-3 and C-7 of the 10H-phenothiazine ring system can easily be furnished with electron-donating or electron-withdrawing groups. Thus, the structural features of 10H-phenothiazine-based dyes guarantee the fabrication of efficient DSSCs. Some 10H-phenothiazine-based dyes show high photovoltaic performance, even better than the commercial ruthenium complex (N719). This paper reviews the recent significant scientific progress in 10H-phenothiazine-based DSSCs and focuses especially on the relationship between the molecular structure and the photoelectric conversion properties.

Phenothiazine-based dyes for efficient dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) have been intensely researched for more than two decades. Electrolyte formulations are one of the bottlenecks to their successful commercialization, since these result in trade-offs between the photovoltaic performance and long-term performance stability. The corrosive nature of the redox shuttles in the electrolytes is an additional limitation for industrial-scale production of DSSCs, especially with low cost metallic electrodes. Numerous electrolyte formulations have been developed and tested in various DSSC configurations to address the aforementioned challenges. Here, we comprehensively review the progress on the development and application of electrolytes for DSSCs. We particularly focus on the improvements that have been made in different types of electrolytes, which result in enhanced photovoltaic performance and long-term device stability of DSSCs. Several recently introduced electrolyte materials are reviewed, and the role of electrolytes in different DSSC device designs is critically assessed. To sum up, we provide an overview of recent trends in research on electrolytes for DSSCs and highlight the advantages and limitations of recently reported novel electrolyte compositions for producing low-cost and industrially scalable solar cell technology.

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Progress on Electrolytes Development in Dye-Sensitized Solar Cells.

Recently, perovskite solar cells have attracted great attention because of their outstanding photovoltaic performance and ease of fabrication. High-quality perovskite films hold a key in getting highly efficient perovskite solar cells. Solution-processed fabrication technique is the most widely adopted for preparing perovskite films because of its low cost. In the solution-proceed perovskite films, solvents not only play the role of dissolving the solute but also participate in the crystallization of perovskite. In the one-step method, solvents play key roles in controlling morphology, widening process window, and achieving room-temperature crystallization of perovskite films. In addition, the solvents play important roles in controlling the nuclei/growth, suppressing volume expansion during the two-step method. Especially, the solvent can induce grain coarsening during the annealing process. A deep understanding of the multiplicity of roles during the formation of perovskite films will help understand th...

A Review of the Role of Solvents in Formation of High-Quality Solution-Processed Perovskite Films

Organic and dye sensitized solar cell devices have attracted a significant attention during last few years in scientific community due to their advantages such as low cost, easy processibility, large scale manufacturing and efficient conversion of solar energy into electrical energy. The main aim of this review is to provide torchlight for organic chemist willing to start exploration in the field of solar cell as it includes an overview of organic and dye sensitized solar cells. This review covers detailed history for development of solar cell, some basic terminologies used in organic and dye sensitized solar cells. The review article gives attention toward synthetic utility of organic molecules for different types of solar cell such as single layer, double layer and bulk heterojunction solar cells, their mechanisms and type of materials which are generally used for solar cell device fabrication. The review specially gives focus on the up to date information about improvements in Organic Solar Cells (OSCs) and Dye Sensitized Solar Cells (DSSCs) which will be a handy tool for young budding researchers to explore the molecular engineering opportunities in terms of designing and synthesizing more efficient exotic materials for solar cell.

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An overview on basics of organic and dye sensitized solar cells, their mechanism and recent improvements

The power conversion efficiency of lead halide perovskite solar cells recently surpassed 22.1%. In this study, we suggest the perovskite absorber growth mechanism of the two-step process could be explained by an Ostwald ripening growth model for planar-structure perovskite solar cells. We attempt to find out the source of two main problems such as unreacted PbI2 and non-uniformed morphology by the proposed ripening growth mechanism and experimental results. This growth mechanism opens the way toward understanding a key aspect of the photovoltaic operation of high-efficiency, two-step perovskite solar cells.

Perspective: Understanding of ripening growth model for minimum residual PbI2 and its limitation in the planar perovskite solar cells

Quasi-solid state electrolyte for semi-transparent bifacial dye-sensitized solar cell with over 10% power conversion efficiency

A comparison of the electronic and photovoltaic properties of novel twin-anchoring organic dyes containing varying lengths of π-bridges in dye-sensitized solar cells

High-quality CH3NH3PbI3 (MAPbI3) crystalline powders were synthesized from a dispersion of MAPbI3 solution (solvent: N,N-dimethylformamide (DMF)) in the antisolvent dichloromethane. They were used as starting chemicals for precursor solutions. The PbI2–DMF-, perovskite-, and PbI2–MAI (methylammonium iodide)–DMF-dominant phases were preferentially formed under conditions of excess PbI2, moderate, and high-excess MAI input ratios, respectively. The input ratio of powders in fabricating the thin MAPbI3 films strongly affected not only the morphology and structure of the films, but also the photovoltaic performance of the devices using them. The devices were constructed as follows: Au/hole-transporting material/MAPbI3/mesoporous TiO2 layer/TiO2 blocking layer/F-doped SnO2. The best device performance was obtained from the powder with a specific ratio of PbI2 : MAI = 1 : 1.6; the device exhibited a power conversion efficiency of ∼16% at 1.5G standard conditions. Our proposed method could provide a simple and versatile solution-based approach for a low-cost perovskite solar cell fabrication technology.

Controlled growth of organic–inorganic hybrid CH3NH3PbI3 perovskite thin films from phase-controlled crystalline powders

1 Green Energy Research Division, Daegu Gyeongbuk Institute of Science & Technology (DGIST), 50-1, Sang-ri, Hyeonpung-myeon, Dalseong-gun, Daegu, 711-873, Republic of Korea 2 Advanced Convergence Research Center, Daegu Gyeongbuk Institute of Science & Technology (DGIST), 50-1, Sang-ri, Hyeonpung-myeon, Dalseong-gun, Daegu, 711-873, Republic of Korea 3 Robotics Research Division, Daegu Gyeongbuk Institute of Science & Technology (DGIST), 50-1, Sang-ri, Hyeonpung-myeon, Dalseong-gun, Daegu, 711-873, Republic of Korea * E-mail: sjsung@dgist.ac.kr; apollon@dgist.ac.kr

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Hyo Jeong Jo

Papers

Perspective: Understanding of ripening growth model for minimum residual PbI2 and its limitation in the planar perovskite solar cells

Quasi-solid state electrolyte for semi-transparent bifacial dye-sensitized solar cell with over 10% power conversion efficiency

A comparison of the electronic and photovoltaic properties of novel twin-anchoring organic dyes containing varying lengths of π-bridges in dye-sensitized solar cells

Controlled growth of organic–inorganic hybrid CH3NH3PbI3 perovskite thin films from phase-controlled crystalline powders

Electrochemical Investigation of High-Performance Dye-Sensitized Solar Cells Based on Molybdenum for Preparation of Counter Electrode