Robust, Scalable Synthesis of the Bulky Hagfeldt Donor for Dye‐Sensitized Solar Cells

Abstract

The bulky triarylamine group commonly referred to as the "Hagfeldtd onor" is ak ey buildingb lock found in many of the organic dyes used in dye-sensitized applications such as dyesensitized solar cells (DSCs). This building block has gained popularity owing to its presence in many of the best-performing DSC devicesr eported to date, which use dyes containing this donorg roup. The Hagfeldt donor provides ad esirable 3dimensionals tructure that aids in surface protection of electrons injected into the semiconductor from oxidants in the electrolyte, allowing for record-setting cobalt-and copperbased redoxs huttles to be utilized more frequently.H owever, the synthesiso ft his molecule has provenu nreliable form any routes. This study concerns an ovel, reliable and scalable fivestep synthesis of the Hagfeldt donor.Supporting Information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Dye-sensitized solar cells strike back

“…Organic dyes have been intensely explored within DSC devices over the last decade with progressively sophisticated designs giving a variety of chromophores tailored to probe various metrics. The demand for higher performing dyes for a range of DSC applications has been assisted by several notable synthetic approaches focused on rapid dye diversification strategies based on one-pot three-component couplings, 250 one-pot four-component couplings, 251 C-H activation-based cross couplings, 252,253 sequential C-H activations, [254][255][256][257][258][259] maskedhalide approaches for sequential couplings, 260 and crossdehydrogenative couplings (Fig. 20).…”

Reactivity and Applications of Iodine Monochloride in Synthetic Approaches

“…The popularity of this deiodosilylation approach with iodine monochloride to access other important, high‐value organic molecules including access to tricyclic carbohydrate‐benzene hybrids [10b] or alternatively towards Hagfeldt donor organic dyes [10c] has also recently been reported last year.…”

The Hagfeldt Donor and Use of Next‐Generation Bulky Donor Designs in Dye‐Sensitized Solar Cells

“…The selectivity challenges present in many other routes can be avoided by the use of a prefunctionalized aryl group with a masked‐halide functional group (Figure ). An example of this strategy was recently published in the literature using an aryl‐trimethylsilane (TMS) group, which provides a functional group that is inert to common cross‐coupling reactions and can be directly converted to an aryl‐iodide in one step . This approach avoids common isomer separation issues compared to many other routes since the TMS‐to‐iodine conversion occurs as an ipso ‐reaction at the position the TMS group is preinstalled on the aryl ring.…”

“…This approach avoids common isomer separation issues compared to many other routes since the TMS‐to‐iodine conversion occurs as an ipso ‐reaction at the position the TMS group is preinstalled on the aryl ring. In the published synthetic route, 4‐bromoresorcinol ( 19 ) is alkylated with 1‐bromo‐2‐ethylhexane in high yield to give arylbromide 20 . Lithium halogen exchange on 20 and addition of trimethoxyborate gives boronic acid 21 upon workup.…”

“…Lithium halogen exchange on 20 and addition of trimethoxyborate gives boronic acid 21 upon workup. This boronic acid can then be coupled to bis‐bromoaryl compound 16 to give the desired bis‐diarylamine 22 (see the literature report for information about the unusual behavior of this compound by 1 H NMR spectroscopy when it is obtained at a high‐purity level). The masked‐halide coupling partner, 1‐bromo‐(4‐trimethylsilyl)benzene, can then be coupled with 22 via Buchwald–Hartwig coupling to give TAA 23 .…”