Twisted Fused-Ring Thiophene Organic Dye-Sensitized Solar Cells

Abstract

Fused-ring thiophene compounds emerged as an important type of building blocks for organic dyes toward the dye-sensitized solar cells (DSSCs) because of their good charge transfer and light-harvesting properties. Nevertheless, some fused-ring thiophenes have a lack of desired alkyl chains or side alkyl chains, which may induce a severe charge recombination in devices. In this work, the hex-1-en-1-ylbenzene (HEYB) unit was introduced in two new fused-ring thiophene organic dyes (M60 and M59), resulting in a modest dihedral angle (∼36°) between the donor and spacer in dyes. The effect of the HEYB unit on optical, electrochemical, and photovoltaic properties has been investigated by comparing with their congeners (M42 and M58) without the HEYB unit. It is found that introduction of the HEYB unit in arylamine donor enhanced the driving force for dye regeneration and beneficial for suppressing dye aggregation as well as reducing the charge recombination. Device performance characteristics demonstrate that introduction of the HEYB unit in the arylamine donor is a feasible strategy toward enhancing the performance of fused-ring thiophene organic dyes. Benefiting from this strategy, a dye-sensitized solar cell employing the M60 photosensitizer and a cobalt electrolyte exhibits a good power conversion efficiency of 9.75% measured under the 100 mW cm–2, simulated AM1.5 sunlight.

New D–π–A dyes incorporating dithieno[3,2-b:2′,3′-d]pyrrole (DTP)-based π-spacers for efficient dye-sensitized solar cells

“…[27][28][29] DTP is accessible with a yield in one step up to 80%, and the N-position provides great opportunity for the control of dye aggregation, which makes it good for DSSC applications. As reported in our previous study, 30 DTP can be easily modied by the introduction of long-chain alkyl groups on the bridging nitrogen, and DSSCs fabricated by these DTP-based dyes achieved a PCE of 8.14%. Wang and co-workers reported a series of arylamine organic dyes bearing N-heterocycle-substituted DTP spacers displayed a PCE of 8.20%.…”

Thiazolo[5,4-d]thiazole-based organic sensitizers with improved spectral properties for application in greenhouse-integrated dye-sensitized solar cells

“…44,45 Dye TTZ11 was instead endowed with a dithieno[3,2-b:2 0 ,3 0 -d] pyrrole (DTP) moiety; in this case a better p-conjugation was expected due to the coplanar bridged p-system, which could possibly lead to an extension of the light absorption range of the sensitizer. [46][47][48] Finally, compound TTZ12 presented both the BTD and the DTP groups on the same molecular scaffold, a combination that was shown to enhance photovoltaic performances compared to dyes presenting the DTP unit alone. 49…”

Asymmetric 8H-Thieno[2′,3′:4,5]thieno[3,2-b]thieno[2,3-d]pyrrole-Based Sensitizers: Synthesis and Application in Dye-Sensitized Solar Cells

“…Nevertheless, most of these works focus on symmetric FTPs, FTPs with an asymmetric structure are rarely exploited, mainly owing to their great challenge of synthesis . Moreover, in our recent work, we proposed that a twisted structure is indispensable for reducing the charge recombination in FTPs based organic dye-sensitized solar cells . Studies revealed that at least 1% PCE improvement can be achieved by introducing the hexyl group in the center of organic dyes without bulky donors.…”