Synthesis of Diketopyrrolopyrrole Derivatives and their use in Singlet Fission, Solar Cells Applications, and Induction of Chirality
Light can generate a chain of reactions that, knowing how to use them, allows us to improve and develop new technological systems that overcome some current issues. One of them is associated with the uncontrolled use of fossil resources making them increasingly scarce. Thus, having the advantage of...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis doctoral |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Universidad Miguel Hernández de Elche |
| Repositorio: | REDIUMH. Depósito Digital de la UMH |
| OAI Identifier: | oai:dspace.umh.es:11000/27473 |
| Acceso en línea: | https://hdl.handle.net/11000/27473 |
| Access Level: | acceso abierto |
| Palabra clave: | Quimica Quimica orgánica Química orgánica CDU::5 - Ciencias puras y naturales::54 - Química::547 - Química orgánica |
| Sumario: | Light can generate a chain of reactions that, knowing how to use them, allows us to improve and develop new technological systems that overcome some current issues. One of them is associated with the uncontrolled use of fossil resources making them increasingly scarce. Thus, having the advantage of using for free the largest existing light source, Solar Energy, several alternatives were taken into consideration to try to fix or mitigate some of the damage generated by this desperate consumption of resources that are not infinite. And for this, it is not only important to test new materials that are more efficient in the use of photovoltaics, but also to understand the phenomena that occur whenever light is absorbed by these materials, and thus make an investigation from the core. This means that it is essential to know the photophysical properties of the materials to be used in order take advantage of the solar energy as much as possible. For this task is necessary to join forces among several areas of knowledge. And it is here that organic chemistry brings many advantages due to the possibility to carry out a rational and systematic modification of the chemical structure of the molecules, thus generating a deep understanding of the structure-property relationship that can allow the fine tuning of the optical/electronic levels of the materials to achieve the best photovoltaic result possible. In this sense, this Thesis is a compilation of some developed works, which are divided into three chapters. The first two share the same essence of studying molecules to improve photovoltaic performance, although the first one is more focused on the study of singlet fission as a photophysical property itself, rather than to its application photovoltaics. The knowledge of this intrinsic property of materials can be used as an asset in this area as it allows to surpass the Schockley- Queisser theoretical efficiency limit . In contrast, Chapter 2 is devoted to the application of several examples of DPP derivatives in OSCs. Finally, Chapter 3, which is not aimed at photovoltaic energy, makes its contribution to the study of the chirality transfer between different moieties, specifically between a chiral inorganic structure and an achiral organic molecule. to improve the problem that sometimes arises in synthesis of the chiral compounds. Specifically, Chapter 1 deals with the design and synthesis of three DPP dimers for application in singlet fission (SF). The molecules differ from each other in the relative position of two diketopyrrolopyrrole (DPP) moieties on the phenylene group (ortho, meta and para), allowing to study the influence of the position of one DPP in relation to the other ( Figure 1 ). Furthermore, the influence of solvent polarity was also studied using benzonitrile as polar solvent and toluene as non- polar one, verifying that SF is strongly influenced by the solvent. As a result, no Abstract VIII triplet states were detected in toluene, while in benzonitrile for derivatives o-DPP 1 and m-DPP 3 it was possible to populate these states from the (S 0S 1) CT state. o- DPP 1 showed the highest SF efficiency due to a greater electronic interaction between the DPP moieties.Abstract VIII triplet states were detected in toluene, while in benzonitrile for derivatives o-DPP 1 and m-DPP 3 it was possible to populate these states from the (S 0S 1) CT state. o- DPP 1 showed the highest SF efficiency due to a greater electronic interaction between the DPP moieties. Figure 1- Structures of the target compounds in Chapter 1. EH- ethylhexyl chain. Chapter 2 focused on the application of DPP derivatives in photovoltaic cells. Two different approaches were taken into account, namely the use in dye sensitized solar cells (DSSCs) and in bulk heterojunction solar cells (BHJs). For the first approach, three DPP- acid derivatives were synthesized and characterized (Figure 2). Two of these molecules had a carboxylic acid as an anchoring group in meta or para position in the phenylene moiety in relation with the DPP core, p-DPP acid 9 and m-DPP acid 10, and the third molecule contained two DPP units on a benzoic acid moiety [(DPP)2 acid 11]. With the increment of DPP moieties it was pretended to increase the photovoltaic performance due to the existence of an intramolecular singlet fission effect. Our expectations were not fulfilled, as the first preliminary tests showed low efficiencies. However, p-DPP acid 9 was the one that presented the best performance, due to a greater electronic interaction.Regarding to the second approach, four new SubPc-DPP derivatives were synthesized for its study as non-fullerene acceptors (NFAs) in inverted-BHJs. The molecules have a conical shape using the SubPc as a core, and three DPPs linked by acetylene bridges as wings (Figure 3). The best efficiency was reached with the PBDB-T:C1-SubPc(DPP) 3-OPh 18 couple with a PCE of 3.17%. However, the most surprising and unexpected result was the high VOC values that were obtained for all derivatives which probably makes these derivatives good candidates for ternary OSCs. Chapter 3 does not follow the spirit of the other chapters having its own meaning as it is an approach in order to combat the problem that exists when synthesizing and purifying chiral compounds (Figure 4). This is based on chirality transfer from nanostructures with chiral morphology to achiral DPP derivatives. Thus, three DPP linked to ortho-, para- and meta-benzoic acids were synthesized, while on the other hand silica nanostructures (helices and ribbons) were developed by a sol-gel method. The link between both systems was made by amide bonding. The optical properties of the linked systems were observed by UV-vis and fluorescence, detecting a red-shift of the spectra. Finally, the chirality was determined with the aid of the absorption dissymmetry factor, gabs, verifying that the greater the distance between the nanostructure and the DPP unit, the greater the value of dissymmetry and the greater the induction of chirality. |
|---|