Search

A new series of 4‐hexyl‐4H‐thieno[3,2‐b]indole (HxTI) based organic chromophores is developed by structural engineering of the electron donor (D) group in the D–HxTI–benzothiadiazole‐phenyl‐acceptor platform with different fluorenyl moieties, such as unsubstituted fluorenyl (SGT‐146) and hexyloxy (SGT‐147), decyloxy (SGT‐148) and hexyloxy‐phenyl substituted (SGT‐149) fluorenyl moieties. In comparison to a reference dye SGT‐137 with a biphenyl‐based donor, the effects of the donating ability and bulkiness of the fluorenyl based donor in this D–π–A‐structured platform on molecular properties and photovoltaic performance are investigated to establish the structure–property relationship. The photovoltaic performance of dye‐sensitized solar cells (DSSCs) is improved according to the bulkiness of the donor groups. As a result, the DSSCs based on SGT‐149 show high power conversion efficiencies (PCEs) of 11.7% and 10.0% with a [Co(bpy)3]2+/3+ (bpy = 2,2′‐bipyridine) and an I−/I3− redox electrolyte, respectively. Notably, the co‐sensitization of SGT‐149 with a SGT‐021 porphyrin dye by utilizing a simple "cocktail" method, exhibit state‐of‐the‐art PCEs of 14.2% and 11.6% with a [Co(bpy)3]2+/3+ and an I−/I3− redox electrolyte, respectively. [ABSTRACT FROM AUTHOR]

Two porphyrin-based sensitizers, SGT-028 and SGT-029 , were designed and synthesized via acceptor engineering for application in dye-sensitized solar cells (DSSCs). Porphyrin SGT-028 was designed by introducing a salicylic acid anchoring group instead of a conventional benzoic acid in the platform of donor-porphyrin-triple bond-BTD-phenyl-acceptor sensitizers (e.g., SGT-021 and SM315). As for SGT-029 , an additional alkylated benzothiadiazole (BTD) unit was substituted to the BTD of D-π-A porphyrin sensitizers. The impact of the anchoring group and long alkyl chains on the optical character, electrochemical property, and photovoltaic performance were studied and also compared with a reference dye of SGT-021 , which had previously been synthesized by our group. As a result, both of these two porphyrin sensitizers obtained a similar absorption range and energy band gap to SGT-021 dye. After performing optimization of DSSC devices, SGT-029 achieved a comparatively high power conversion efficiency (PCE) of 10.5%, but was inferior to the benchmark porphyrin sensitizer SGT-021 (12.7%), and a slightly lower PCE of 9.1% was exhibited by SGT-028 , under the standard AM 1.5G light intensity. It is worth mentioning that the PCE of 12.7% is the highest efficiency for a SGT-021 -based device up to now. The main reason was supposed to be the dye adsorption amount difference, maybe allowing for a serious dye aggregation, which often leads to an increased quenching of excited states and limits the charge injection into the TiO 2 semiconductor substrate, and lower light harvest efficiency (LHE), resulting in lower photocurrent, photovoltage, and PCE. • Porphyrin-based D-π-A dyes SGT-028 and SGT-029 were synthesized. • The effect of acceptor groups on the photovoltaic properties was investigated. • The retardation of aggregation and the dye adsorption amount loss were discussed. • High efficiency of 9.1%, 10.5% and 12.7% were achieved for SGT-028 , SGT-029 and SGT-021 -based DSSCs, respectively. [ABSTRACT FROM AUTHOR]

Dye-Sensitized Solar Cells: 14.2% Efficiency Dye-Sensitized Solar Cells by Co-sensitizing Novel Thieno[3,2-b]indole-Based Organic Dyes with a Promising Porphyrin Sensitizer (Adv. Keywords: co-sensitization; dye-sensitized solar cells; D- -A structure; organic dyes; structure-performance relationship EN co-sensitization dye-sensitized solar cells D- -A structure organic dyes structure-performance relationship 1 1 1 04/23/20 20200421 NES 200421 In article number 2000124, Hwan Kyu Kim and co-workers develop a series of highly efficient organic dyes and a simple co-sensitization method for dye-sensitized solar cells with state-of-the-art efficiency. Co-sensitization, dye-sensitized solar cells, D- -A structure, organic dyes, structure-performance relationship. [Extracted from the article]

Tellurium-doped, mesoporous carbon nanomaterials with a relatively high doping level were prepared by a simple stabilization and carbonization method in the presence of a tellurium metalloid. A transparent counter electrode (CE) was prepared using tellurium-doped, mesoporous carbon (TeMC) materials, and was directly applied to bifacial, dye-sensitized solar cells (DSSCs). To improve the performance of the bifacial DSSC device, CEs should have outstanding electrocatalytic activity, electrical conductivity, and electrochemical stability, as well as high transparency. In this study, to make transparent electrodes with outstanding electrocatalytic activity and electrical conductivity, various TeMC materials with different carbonization temperatures were prepared by simple pyrolysis of the polyacrylonitrile-block-poly (n-butyl acrylate) (PAN-b-PBA) block copolymer in the presence of the tellurium metalloid. The electrocatalytic activity of the prepared TeMC materials were evaluated through a dummy cell test, and the material with the best catalytic ability was selected and optimized for application in bifacial DSSC devices by controlling the film thickness of the CE. As a result, the bifacial DSSC devices with the TeMC CE exhibited high power conversion efficiencies (PCE), i.e., 9.43% and 8.06% under front and rear side irradiation, respectively, which are the highest values reported for bifacial DSSCs to date. Based on these results, newly-developed transparent, carbon-based electrodes may lead to more stable and effective bifacial DSSC development without sacrificing the photovoltaic performance of the DSSC device. [ABSTRACT FROM AUTHOR]

The rational design of porphyrin sensitizers is always crucial for dye-sensitized solar cells (DSSCs), since the change of only a single atom can have a significant influence on the photovoltaic performance. We incorporated the pyridothiadiazole group, as a stronger electron-withdrawing group, into the commonly well-established skeleton of D-porphyrin-triple bond-acceptor sensitizers by a single atom change for a well-known strong electron-withdrawing benzothiadiazole (BTD) unit as an auxiliary acceptor. The impact of the pyridothiadiazole group on the optical; electrochemical; and photovoltaic properties of D–π–A porphyrin sensitizers was investigated with comparison for a benzothiadiazole-substituted SGT-020 porphyrin. The pyridothiadiazole-substituted SGT-024 porphyrin dye was red-shifted so that the absorption range might be expected to achieve higher light harvest efficiency (LHE) than the SGT-020 porphyrin. However, all the devices were fabricated by utilizing SGT-020 and SGT-024, evaluated and found to achieve a cell efficiency of 10.3% for SGT-020-based DSSC but 4.2% for SGT-024-based DSSC under standard global AM 1.5G solar light conditions. The main reason is the lower charge collection efficiency of SGT-024-based DSSC than SGT-020-based DSSC, which can be attributed to the tilted dye adsorption mode on the TiO2 photoanode. This may allow for faster charge recombination, which eventually leads to lower Jsc, Voc and power conversion efficiency (PCE). [ABSTRACT FROM AUTHOR]