Dye-sensitized solar cells (DSSCs) Dye-sensitized solar cells (DSSCs) have been regarded as one of the most prospective solar cells, due to low-cost, flexibility, simple device fabrication and high conversion efficiency, in comparison to the conventional photovoltaic devices. Recently, G2E in Swiss and Exeger in Sweden including Asian companies have demonstrated prototyped components based on DSSC technology employing liquid electrolytes. A state of the art DSSC based on organic sensitizer-, porphyrin-based SCs as well as Ru-complex-based SCs has exceeded the power conversion efficiency (PCE) of over 14.3 %, 13% and 11.9%, respectively. However, the unit costs, long-term device stability and power conversion efficiency must be further improved for real-life applications. In this regard, we demonstrated that D–π–A structured Zn(II)–porphyrin and organic sensitizers for efficient retardation of charge recombination and fast dye regeneration were newly designed and synthesized [1-4]. The device with new porphyrin sensitizer exhibited the higher PCE than those of the devices with SM315 as a world champion dye. To further improve the maximum efficiency of the DSSCs, very recently, the cocktailed co-sensitization of new organic sensitizer with a porphyrin dye showed state-of-the-art PCEs of 14.20% [5]. Also, to improve the long-term device stability, triblock copolymer-based quasi-solid state (QSS) DSSCs with significantly improved long-term device stability exhibited an overall photovoltaic PCE of 10.49%, which is higher than a liquid electrolyte-based DSSC [5]. Also, the best PGE was applied to QSS-DSSCs based on the co-sensitization of organic dye and porphyrin dye. As a result, the PCEs of both polymer gel electrolytes and polymer/TiO2 composite gel electrolytes based QSS-DSSCs were comparable with liquid-state DSSCs. The highest PCE measured for polymer and polymer/TiO2 composite gel electrolytes was 10.97% and 11.05%, respectively [6-7]. These are the highest values reported for QSS-DSSCs. The long-term stability of QSS-DSSCs was better than liquid state DSSCs, retaining > 80% of its initial PCE after 2000 hours of testing at 50°C under 1-sun condition. Furthermore, we have searched low-cost, scalable metal-free counter electrodes (CEs) based on carbon-based nanomaterials with improved fill factor and low-cost for alternative to expensive and noble Pt metal CEs[8-9], those factors of which limit large scale production and thus prohibit the practical application of DSSCs. In this presentation, D–π–A structured Zn(II)–porphyrin sensitizers with donor and acceptor structural engineering for superior performance dye-sensitized solar cells will be described.

References:

[1] Y. K. Eom and H. K. Kim, et.al., Advanced Energy Materials, 5, 1500300/1-10 (2015).

[2] S. H. Kang and H. K. Kim, et.al., Advanced Energy Materials, 7, 1602117/1-10 (2017).

[3] Y. K. Eom and H. K. Kim, et.al., J. Mater. Chem. A, 5, 2297 (2017).

[4] J. M. Ji and H. K. Kim, et.al., J. Mater. Chem. A, 6, 1. 14518 (2018). (Invited Review Article)

[5] J. M. Ji and H. K. Kim, et.al., Advanced Energy Materials, 10, 2000124/1-12 (2020).

[6] S. M. Seo and H. K. Kim, et.al., J. Mater. Chem. A, 7, 14743 (2019).

[7] Masud and H. K. Kim, et.al., ACS Applied Materials & Interface, 12, 42067 (2020).

[8] C. K. Kim and H. K. Kim, et.al., ACS Applied Materials & Interface, 11, 2093 (2019).

[9] M. Aftabuzzaman, C. Lu, and H. K. Kim, Nanoscale, 12, 17590 (2020). (Invited Review Article)