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Project titleDevelopment of novel functional materials based on conjugated donor-acceptor oligomers for organic photovoltaics

Research area 03 - CHEMISTRY AND MATERIAL SCIENCES, 03-301 - Synthesis and chemical transformations of macromolecules

Keywordsconjugated oligomers, donor-acceptor molecules, oligothiophene, optical properties, organic semiconductor, organic solar cells

Annotation
As a result of the project, new classes of donor-acceptor conjugated oligomers - promising semiconductor materials for usage in organic solar cells will be developed. A thorough study of their properties (optical, electrochemical and thermal) will reveal main structure-property relationships for such classes of compounds, which will allows not only predict and fine-tune their various physicochemical parameters, but also design materials with predetermined properties. Experimental results obtained will make it possible to significantly make progress the molecular design of organic semiconductors that meet all the requirements for creating highly efficient and stable organic solar cells. The importance of development aimed at creating new alternative energy sources does not need special justification and, of course, is considered to be high in both the economic and social spheres. In the case of obtaining patentable results and the need to protect intellectual property, an application for the invention will be filed. Practical use and implementation of the results is planned for 2-3 years after the end of the project in the development of the production technology of flexible and / or semitransparency organic solar cells, which is conducted in the small innovative enterprise LLC Organik Solartec, which received resident status in Skolkovo (2016). Planned results, both on the use of modern research methods and on their scientific significance, fully correspond to the world level of research in the field of organic electronics, the criterion of which will be, their publication in leading domestic and foreign scientific journals, indexed in the Web of Science and impact factors 2-6, such as Organic Electronics, Dyes and Pigments, Synthetic Metals, Journal of Materials Chemistry C, Mendeleev Communications, etc. The best results are planned to be published in journals with impact factor 7-20, such as, for example, the Journal of Materials Chemistry A, ACS Applied Materials and Interfaces, the Chemistry of Materials, Advanced Functional Materials, Advanced Energy Materials Science, etc.

Expected results
As a result of the project, new classes of donor-acceptor conjugated oligomers - promising semiconductor materials for usage in organic solar cells will be developed. A thorough study of their properties (optical, electrochemical and thermal) will reveal main structure-property relationships for such classes of compounds, which will allows not only predict and fine-tune their various physicochemical parameters, but also design materials with predetermined properties. Experimental results obtained will make it possible to significantly make progress the molecular design of organic semiconductors that meet all the requirements for creating highly efficient and stable organic solar cells. The importance of development aimed at creating new alternative energy sources does not need special justification and, of course, is considered to be high in both the economic and social spheres. In the case of obtaining patentable results and the need to protect intellectual property, an application for the invention will be filed. Practical use and implementation of the results is planned for 2-3 years after the end of the project in the development of the production technology of flexible and / or semitransparency organic solar cells, which is conducted in the small innovative enterprise LLC Organik Solartec, which received resident status in Skolkovo (2016). Planned results, both on the use of modern research methods and on their scientific significance, fully correspond to the world level of research in the field of organic electronics, the criterion of which will be, their publication in leading domestic and foreign scientific journals, indexed in the Web of Science and impact factors 2-6, such as Organic Electronics, Dyes and Pigments, Synthetic Metals, Journal of Materials Chemistry C, Mendeleev Communications, etc. The best results are planned to be published in journals with impact factor 7-20, such as, for example, the Journal of Materials Chemistry A, ACS Applied Materials and Interfaces, the Chemistry of Materials, Advanced Functional Materials, Advanced Energy Materials Science, etc.

Annotation of the results obtained in 2021
As a result of the final third stage of the project, taking into account the analysis of the literature, as well as the data obtained during the previous stages, the molecular design of new conjugated acceptor oligomers of various structures was proposed and developed, having: (TDATTPI-IC), non-fused biphenyl (TPPT-IC), or dithienosilene (DTST-IC) central fragments without or with a thiophene π-spacer fragment conjugated with terminal electron-withdrawing substituents based on indan-1-one-3-dicyanovinyl. The synthesis of these compounds was carried out according to the developed efficient synthesis schemes. New non-fullerene acceptor oligomers TDATTPI-IC, TPPT-IC and DTST-IC were isolated in an individual state, and their chemical structure and high purity were proved by a complex of modern physicochemical research methods. The optical, electrochemical, and thermal properties of the obtained oligomers were studied by absorption spectroscopy, cyclic voltammetry, thermogravimetric analysis, and differential scanning calorimetry, respectively. It was shown that all synthesized new oligomers effectively absorb visible radiation in a wide spectral range, reaching the far red, near IR region of the solar radiation spectrum, for example, up to 1060 nm in the case of the DTST-IC acceptor oligomer, which exceeds similar values for the commercial acceptor material of the latter. generations - Y6. The experimental values of the electrochemical band gap for the TDATTPI-IC oligomer are comparable to those for commercial IDIC, and in the case of DTST-IC, this value turned out to be smaller than that of Y6. It has been shown that the use of various central fragments not only leads to a change in the level of HOMO of oligomers, but also has a significant effect on the level of LUMO. The key role in this phenomenon is played by the nature of the central fragment, i.e. the contribution of the central donor or acceptor unit to the total electron density of the molecule. It has been demonstrated that the use of a central relatively strong electron donor moiety, for example, dithienosilol in combination with strong indan-1-one-3-dicyanovinyl EA groups, as well as the use of a strategy of non-covalent intramolecular O···S interactions, are promising tools for obtaining medium- and narrow-gap nonfullerene acceptor oligomers. The best of the previously developed and synthesized donor oligomers of linear (7T-CNA) and star-shaped (BTI-2T-CNA) architectures were first tested in prototypes of non-fullerene OSBs with the latest generation of NFAs, Y6. Comparison of the results obtained in this year with those previously demonstrated at the previous stage for oligomers 7T-CNA and BTI-2T-CNA in a mixture with a non-fullerene acceptor of the previous generation - IDIC allowed us to establish that the linear donor oligomer 7T-CNA works better in a mixture with Y6, then as star-shaped BTI-2T-CNA in a mixture with IDIC, and the achieved values of output parameters are comparable with similar world analogues based on donor oligothiophenes and even exceed in the case of star-shaped oligomers. Among the obtained acceptor oligomers, the mixture based on DTST-IC and BTI-2T-CNA proved to be the best. To optimize the morphology and further improve the output characteristics of the devices, it was proposed to increase the solubility of such acceptors by elongating the central alkyl groups, which gives groundwork for the further successful development of this direction. It has also been shown that DTST-IC can be used as an additional near-infrared absorbing component to binary mixtures in OSCs, significantly increasing the efficiency of such devices. During the third stage, 3 articles were published in international high-ranking scientific journals indexed in the Web of Science and Scopus databases (2 papers from the Q1 and 1 from Q2 quartiles). The results obtained at the third stage of the project were presented in the form of 1 invited, 2 oral and 3 poster presentations at international and all-Russian specialized scientific conferences.

Publications

1. A. N. Solodukhin, Yu. N. Luponosov, A. L. Mannanov, P.S. Savchenko, A.V. Bakirov, M.A. Shcherbina, S. N. Chvalun, D. Yu. Paraschuk, S. A. Ponomarenko Donor Core Effect in D-π-A Star-Shaped Small Molecules on Their Properties and Performance in Single-Component and Bulk-Heterojunction Organic Solar Cells Energies, 14, 3596 (year - 2021) https://doi.org/10.3390/en14123596

2. Alina F. Latypova, Nikita A. Emelianov, Dmitry O. Balakirev, Polina K. Sukhorukova, Nadezhda K. Kalinichenko, Petr M. Kuznetsov, Yuriy N. Luponosov, Sergey M. Aldoshin, Sergey A. Ponomarenko, Pavel A. Troshin, Lyubov A. Frolova Design Principles for Organic Small Molecule Hole-Transport Materials for Perovskite Solar Cells: Film Morphology Matters ACS Applied Energy Materials, 10.1021/acsaem.1c03119 (year - 2022) https://doi.org/10.1021/acsaem.1c03119

3. N. K. Kalinichenko, D. O. Balakirev, P. S. Savchenko, A. L. Mannanov, S. M. Peregudova, D, Yu. Paraschuk, S. A. Ponomarenko, Yu. N. Luponosov Effects of electron-withdrawing group and π-conjugation length in donor-acceptor oligothiophenes on their properties and performance in non-fullerene organic solar cell Dyes and Pigments, том 194, 109592 (year - 2021) https://doi.org/10.1016/j.dyepig.2021.109592

Annotation of the results obtained in 2019
As a result of the project, in the first year using molecular modeling methods, a new molecular design was developed for new conjugated oligomers of the donor-acceptor (D-A) structure having benzodithiophene, triindole or acridine electron-donor centers conjugated via bi- or tertiophene spacers with terminal alkyldicyanovinyl or cyanoether electronwithdraing groups. Effective synthesis schemes were developed for such compounds and their first representatives were obtained. All obtained D-A oligomers were isolated in an individual state, and their chemical structure and high purity were proved by a complex of modern physicochemical methods, including GPC, 1H and 13C NMR spectroscopy, elemental analysis and mass spectrometry. The optical, electrochemical, thermal, and structural properties of the obtained oligomers were studied by absorption spectroscopy, cyclic voltammetry, differential scanning calorimetry, and thermogravimetric analysis. Comparison of the properties of the obtained oligomers depending on the varied parameters of their chemical structure made it possible to identify the main elements of the structure-property relationship. It was found that oligomers with cyanoester groups have a hypochromic shift in the absorption spectra in solutions, but have greater crystallinity. By the example of a star-shaped oligomer with an acridine electron-donor center, it was shown that such oligomers have a number of significant advantages for use in organic solar cells compared to the analog based on triphenylamine. There are an increased solubility and thermal stability in combination with a reduced band gap and high crystallinity. Because of this, organic solar cells based on such compounds have high charge mobility and a record value of efficiency for solar cells based on star-shaped compounds and fullerene acceptors. The knowledge gained will allow us to predict and fine-tune the properties of such compounds and significantly advance on the path to creating effective and stable organic solar cells. During the project, 2 articles were published in international highly rated scientific journals (from Q1 quartile), indexed in the Web of Science and Scopus databases. The results were also presented in the form of oral presentations at international specialized scientific conferences.

Publications

1. Balakirev D.O, Luponosov Yu. N., Mannanov A.L., Savchenko P. S., Minenkov Y., Paraschuk D. Yu., Ponomarenko S. A. Star-shaped benzotriindole-based donor-acceptor molecules: synthesis, properties and application in bulk heterojunction and single-material organic solar cells Dyes and Pigments, - (year - 2020)

2. Guo J., Balakirev D.O., Gu C., Peregudova S.M., Ponomarenko S.A., Liu Z., Luponosov Yu. N., Min J., Lei A. End group tuning in small molecule donors for non-fullerene organic solar cells Dyes and Pigments, volume 175, p. 108078 (year - 2020) https://doi.org/10.1016/j.dyepig.2019.108078

3. Luponosov Yu. N., Solodukhin A.N., Mannanov A.L., Savchenko P. S., Minenkov Y., Paraschuk D. Yu., Ponomarenko S. A. Effect of fused triphenylamine core in star-shaped donor-π-acceptor molecules on their physicochemical properties and performance in bulk heterojunction organic solar cells Dyes and Pigments, 177, 108260 (year - 2020) https://doi.org/10.1016/j.dyepig.2020.108260

Annotation of the results obtained in 2020
As a result of the implementation of the second stage of the project, taking into account the analysis of the results obtained in the first year, a molecular design of new conjugated oligomers of donor-acceptor (D-A) structure with benzodithiophene, benzotriindole or thiophene electron-donor centers, coupled linked to the terthiophene spacer with terminal alkyldicyanovinyl or cyanoacetate electron-withdrawing groups. The synthesis of such compounds was carried out according to the efficient schemes developed at the first stage. All obtained D-A oligomers were isolated in an individual state, and their chemical structure and high purity were proved by a complex of modern physicochemical methods, including GPC, 1H and 13C NMR spectroscopy, elemental analysis and mass spectrometry. The optical, electrochemical, and thermal properties of the obtained oligomers were investigated by absorption spectroscopy, cyclic voltammetry, differential scanning calorimetry, and thermogravimetric analysis, respectively. Comparison of the obtained compounds with the oligomers obtained at the first stage of the project made it possible to reveal the effect of the length of the oligothiophene spacer on their properties and parameters of photovoltaic devices. It was found that an increase in the conjugation length leads to an increase in the energies of the HOMO levels, a narrowing of the band gap, noticeably affects the solubility, phase behavior and absorption spectra in thin films, has a pronounced positive effect on the efficiency of photocells in the case of linear oligomers and a negative effect in the case of star-shaped oligomers. The study of the photovoltaic properties of the obtained compounds in blends with fullerene (PC71BM) and non-fullerene (IDIC) acceptors made it possible for the first time to draw an important and valuable conclusion for the further development of effective donor materials: oligomers with cyanoacetate acceptor groups form more effective photovoltaic mixtures with IDIC, whereas oligomers with dicyanovinyl acceptor groups with PC71BM. In the course of the project, the possibility and prospects of using star-shaped donor compounds in a mixture with non-fullerene acceptors were shown for the first time. In the course of the project, following the results of two stages, 3 articles were published in international top-rated scientific journals (from the Q1 quartile), indexed in the Web of Science and Scopus databases, and 2 more were submitted to the editors of the journals. The results obtained at the 2nd stage of the project were presented in the form of 2 invited, 1 oral and 7 poster presentations at international and all-Russian specialized scientific conferences.

Publications

1. Kalinichenkoa N.K.,Balakireva D.O., Savchenko P.S., Mannanov A.L., Peregudova S.M., Paraschuk D.Yu., Ponomarenko S.A., Luponosov Yu.N. Effects of electron-withdrawing group and π-conjugation length in donor-acceptor oligothiophenes on their properties and performance in non-fullerene organic solar cells Dyes and Pigments, - (year - 2021)

2. Solodukhin A., Luponosov Yu., Mannanov A., Savchenko P., Bakirov A., Shcherbina M., Chvalun S., Paraschuk D., Ponomarenko S. Branched electron‐donor core effect in D‐π‐A star‐shaped small molecules on their properties and performance in single‐component and bulk‐heterojunction organic solar cells Energies, - (year - 2021)