Defense of the dissertation of Ibrayeva Ayagoz for the degree of Doctor of Philosophy (PhD) in the specialty «8D05306 - Chemistry»

L.N. Gumilyov Eurasian National University, a dissertation defense for the degree of Doctor of Philosophy (PhD) by Ibrayeva Ayagoz on the topic «Design of highly effective novel electrolytes for photovoltaic application» to the educational program «8D05306 – Chemistry».

The dissertation was carried out at the «Chemistry education department» of L.N. Gumilyov Eurasian National University.

The language of defense is English

Official reviewers:

Toktarbay Zhexenbek – PhD, Professor, Abay Kazakh National Pedagogical University (Almaty, Republic of Kazakhstan);

Nazhipkyzy Meruert – Candidate of Chemical Sciences, Professor, Al-Farabi Kazakh National University (Almaty, Republic of Kazakhstan).

Temporary members of the Dissertation Council:

Moulay Rachid Babaa - PhD, Associate Professor, New Uzbekistan University (Tаshkent, Republic of Uzbekistan);

Mashentseva Anastasia Alexandrovna – PhD, Professor, Technological Laboratory for Track Membranes (Astana, Republic of Kazakhstan);

Nurbekova Marzhan Abdyzhaparovna - Candidate of Chemical Sciences, Acting Associate Professor, Kazakh National Women's Teacher Training University (Almaty, Republic of Kazakhstan).

Scientific advisors:

Tashenov Yerbolat Ordabekovich – PhD, Acting Docent, Department of Chemistry, L.N. Gumilyov Eurasian National University (Astana, Republic of Kazakhstan);

Robert J. O'Reilly – PhD, Medical doctor (MD), Lecturer at the School of Science and Technology University of New England (Armidale, Australia).

The defense will take place on May 13, 2026, at 10:00 AM in the Dissertation Council for the training direction «8D053 – Physical and chemical sciences» in the specialty «8D05306 – Chemistry» of L.N. Gumilyov Eurasian National University. The dissertation council meetings will be held offline and online.

Link: https://teams.microsoft.com/meet/41298813559692?p=rrff7wbZbFXMIOYNRF 

Address: Kazhymukan Street, 13, Room: 333, Astana

Abstract (English): ABSTRACT of the dissertation work of Ibrayeva Ayagoz Kairullakyzy on the topic «Design of highly effective novel electrolytes for photovoltaic application» submitted for the degree of Doctor of Philosophy (PhD) in educational program «8D05306 – Chemistry» General description of the work. The dissertation work is focused on the design and development of highly efficient and stable quasi-solid and solid-state electrolytes based on porous structured materials and carbazole-derived compounds. These include hole-transporting materials and non-metallic dyes for advanced photovoltaic applications. The study comprehensively evaluates the synthesized materials, such as metal–organic frameworks (MOFs) and covalent–organic frameworks (COFs) and optimizes the prepared electrolytes for both indoor and outdoor operational conditions. Additionally, it examines the electrochemical and photovoltaic properties of the fabricated dye-sensitized solar cells (DSSCs). Relevance of the research topic. Dye-sensitized solar cells (DSSCs) represent one of the most promising third-generation photovoltaic technologies due to their unique combination of low-cost fabrication, aesthetic tunability, mechanical flexibility, and high performance under diffuse and indoor illumination. Problems such as solvent leakage, evaporation, corrosion, and thermal degradation significantly reduce device lifetime and efficiency. To overcome these drawbacks, research in recent years has shifted toward the development of quasi-solid and solid-state electrolytes that combine the ionic conductivity of liquids with the mechanical stability of solids. Within this context, porous frameworks, such as MOFs and COFs, have emerged as a new class of materials with exceptional tunability, high surface area, and ordered channels for ion and charge transport. Their incorporation into electrolyte systems offers opportunities to enhance charge mobility, suppress recombination, and prevent leakage, while maintaining chemical stability under extended operation. Furthermore, the literature review of carbazole-based hole-transporting materials and non-metallic dyes provides additional pathways to improve light absorption, charge transfer, and energy level alignment in DSSCs. Therefore, the present dissertation work addresses an urgent scientific and technological challenge: the creation of durable, high-performance, and cost-effective electrolytes for sustainable photovoltaic devices. The work contributes to the global effort to make solar energy not only a competitive alternative to fossil fuels but also a viable energy source for diverse environments, ranging from outdoor solar panels to low-light indoor systems. By integrating insights from materials chemistry, electrochemistry, and device engineering, this study advances the understanding and application of hybrid electrolyte systems, directly supporting the United Nations Sustainable Development Goal (SDG) 7: “Affordable and Clean Energy.” Research purpose: to design and characterize electrolyte materials that enhance the stability and performance of dye-sensitized solar cells. Research tasks: 1. Synthesize new porous materials, including MOFs, COFs and carbazole-based compounds (hole-transporting materials). 2. Conduct detailed physicochemical characterization of the synthesized materials using SEM, TEM, XRD, TGA, N2 adsorption–desorption analysis, XPS, FT-IR and NMR spectroscopy. 3. Optimize additive concentrations and electrolyte compositions to improve DSSCs performance. 4. Fabricate DSSCs incorporating solid-state, liquid and quasi-solid electrolyte systems and conduct the structural characteristics of the synthesized materials with the electrochemical and photovoltaic behavior of the devices. Object of the research: Electrolytes based on the iodide/triiodide (I⁻/I3⁻) redox couple in dye-sensitized solar cells. Main provisions submitted for defense: 1. It has been shown that the use of carbazole derivatives for the synthesis of small organic molecules enables the formation of novel structures with potentially high functional properties, suitable for application as hole-transporting materials and electrolytes. Based on a critical analysis of the literature, the use of carbazole in the synthesis of small organic compounds is justified as a promising yet insufficiently explored approach, opening new opportunities for the development of functional materials for photoelectrochemical applications. 2. It has been demonstrated that the incorporation of MIL-125 into an iodide/triiodide quasi-solid-state electrolyte increases the power conversion efficiency from 9.14% to 10.51%, enhances the short-circuit current density from 18.01 to 20.97 mA cm-2, reduces charge-transfer resistance (1.79 vs. 1.99 Ω), increases ionic conductivity (3.36 vs. 3.02 mS cm-1), and ensures stable operation for 60 days, while achieving 25.9% PCE under low-light illumination (6000 lx). 3. It has been established that the addition of a triazine-based covalent organic framework (COF) to the liquid electrolyte increases the power conversion efficiency from 8.87% to 10.81%, improves the short-circuit current density from 15.85 to 18.60 mA cm-2, reduces charge-transfer resistance (3.0 vs. 5.5 Ω), enhances ionic conductivity (2.01 vs. 1.11 mS cm⁻¹) and the apparent diffusion coefficient (7.54 × 10-16 vs. 3.2 × 10-16 cm2 s-1), and maintains operational stability for 40 days, with a PCE of 27.4% under low-light conditions (6000 lx). Scientific novelty: 1. This study introduces a simple, polymer-free strategy for converting a conventional iodide liquid electrolyte into a stable quasi-solid system using a Ti-based MIL-125 metal–organic framework, achieving enhanced charge transport, suppressed electrolyte leakage and record indoor-light efficiencies in dye-sensitized solar cells. 2. For the first time introduces a previously unexplored electrolyte-engineering strategy in which a triazine-based covalent organic framework is directly incorporated into a conventional iodide liquid electrolyte, enabling simultaneous enhancement of ionic transport, redox stability, long-term durability, and indoor-light efficiency in dye-sensitized solar cells. 3. Post-operation analyses (SEM, XRD, FTIR, XPS) confirmed that both MIL-125 and COF frameworks preserve their crystalline and chemical integrity after extended use. 4. A systematic study uniquely consolidates and critically analyzes carbazole-based molecules as both sensitizers and hole-transport materials in dye-sensitized solar cells, establishing structure–property–performance relationships and identifying design strategies for efficient, stable and low-cost photovoltaic devices. Theoretical significance of the study. The dissertation provides a theoretical foundation for understanding ion transport and charge-transfer phenomena in DSSCs modified with porous framework materials. It advances the comprehension of donor–π–acceptor interactions, energy level alignment, and charge transport in organic semiconductors. These insights establish molecular design principles for next-generation sensitizers and transport layers, contributing to materials chemistry, electrochemistry, and photovoltaic science. Practical significance of the study. This work offers a scalable approach for developing stable, high-efficiency DSSCs through MOF- and COF-based electrolytes. The resulting materials demonstrate low production costs, long-term operational stability, and superior light-harvesting performance in both indoor and outdoor environments which makes them promising candidates for next-generation photovoltaic technologies and self-powered electronic systems. Relations to research programs. The research was supported by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan Grant № AP23490505 Indoor photovoltaics based on solid-state dye-sensitized solar cells of advanced architecture and № АР14870560 Development of Low-Cost, Bifacial indoor Dye-Sensitized Photovoltaic for Sustainable Internet of Things Application. Author’s personal contribution. The author designed, synthesized and optimized MOFs (MIL-125), triazine-based COFs, also reviewed carbazole-based hole-transporting materials and non-metallic dyes. She performed electrolyte formulation, material characterization, DSSCs fabrication, and device testing, establishing structure–property–performance correlations. The author also filed patent applications, prepared and revised publications, and coordinated with supervisors and co-authors throughout the research process. For the research article titled ‘Engineering stable electrolytes with covalent organic frameworks to boost dye-sensitized solar cell efficiency’ author contribution is writing – original draft, visualization, validation, methodology, investigation, formal analysis, data curation, conceptualization. For the second research article titled ‘Enhancing the stability and efficiency of dye-sensitized solar cells with MIL-125 metal-organic framework as an electrolyte additive’ author contribution is conceptualization, methodology, software, validation, formal analysis, investigation, re­sources, data curation, visualization, writing-original draft preparation. For the review article titled ‘Advancements in carbazole-based sensitizers and hole-transport materials for enhanced photovoltaic performance’ author contribution is conceptualization, visualization, investigation, formal analysis, data curation, writing original draft. Publications: The dissertation findings are supported by three peer-reviewed articles in Scopus- and Web of Science-indexed journals, one utility model patent, and several presentations at international scientific conferences. List of publications based on the research results: 1. Ayagoz Ibrayeva, Diana Suleimenova, Zulfiya Imanbekova, Urker Abibulla, Bakhytzhan Baptayev, Mannix P. Balanay. Engineering stable electrolytes with covalent organic frameworks to boost dye-sensitized solar cell efficiency // Materials Today Energy (2025) Vol. 54, Article № 102088. https://doi.org/10.1016/ j.mtener.2025.102088. The article is indexed in the Web of Science Core Collection and Scopus databases. At the time of its publication in 2025, the journal Materials Today Energy had aт Impact Factor of 8.6 (2024) and was ranked in Quartile Q1 in the categories of chemistry, physics, energy and fuel, materials science, multidisciplinary. The journal also had a 2024 CiteScore of 16.7, with percentile rankings nuclear energy and engineering – 96, energy engineering and power technology – 94, fuel technology- 92, materials science (miscellaneous) – 92, and renewable energy, sustainability and the environment – 89. 2. Ayagoz Ibrayeva, Zulfiya Imanbekova, Urker Abibulla, Yerbolat Tashenov, Bakhytzhan Baptayev, Mannix P. Balanay. Enhancing the stability and efficiency of dye-sensitized solar cells with MIL-125 metal-organic framework as an electrolyte additive // Scientific Reports (2025) Vol. 15, Article № 5883. https://doi.org/10.1038/s41598-025-89913-1. The article is indexed in the Web of Science Core Collection and Scopus databases. At the time of its publication in 2025, the journal Scientific Reports had an Impact Factor of 3.9 (2024) and was ranked in Quartile Q1 in the multidisciplinary sciences category. The journal also had a CiteScore of 6.7 for 2024, with percentile ranking in the multidisciplinary field – 89. 3. Ayagoz Ibrayeva, Urker Abibulla, Zulfiya Imanbekova, Bakhytzhan Baptayev, Robert J. O’Reilly, Mannix P. Balanay. Advancements in carbazole-based sensitizers and hole-transport materials for enhanced photovoltaic performance // Molecules (2024) Vol. 29, Article № 5035. https://doi.org/10.3390/molecules29215035. The article is indexed in the Web of Science Core Collection and Scopus databases. At the time of its publication in 2024, the journal Molecules had an Impact Factor of 4.2 (2023) and was ranked in Quartile Q2 in the categories of chemistry, multidisciplinary and biochemistry and molecular biology. Its 2023 CiteScore was 7.4, with the following percentiles: chemistry (miscellaneous) – 83, organic chemistry – 81, physical and theoretical chemistry – 80, analytical chemistry – 78, pharmaceutical science – 81, drug discovery – 73 and molecular medicine – 68. Patent for utility model: Diana Suleimenova, Ayagoz Ibrayeva, Bakhytzhan Baptayev, Mannix P.Balanay. Method of improving stability and efficiency of dye-sensitized solar cells. – KZ Patent № 11169 (19 September 2025). List of presentations at international scientific conferences: 1. Ibrayeva A., Suleimenova D., Imanbekova Z., Baptayev B., Balanay M.P. Metal-organic frameworks and covalent organic frameworks as electrolyte enhancers: a pathway to high-efficiency and stable DSSCs // Silk Road Chemistry: Modern Chemical Technologies and Science: Collection of abstracts of the 1st International Scientific and Practical Conference dedicated to the 100th anniversary of Academician Ye.A. Buketov. – Karaganda: Karaganda National Research University named after Academician Ye.A. Buketov, 2025. – September 25–27. 2. Ibrayeva A., Suleimenova D., Imanbekova Z., Abibulla U., Baptayev B., Balanay M.P. A new avenue for enhancing DSSC performance using covalent organic frameworks in electrolytes // The 4th International Symposium on Emerging Materials and Devices (ISEMD-2025). – Astana: Nazarbayev University, National Laboratory Astana, 2025. – May 28–30. 3. Ibrayeva A., Imanbekova Z., Abibulla U., Baptayev B., Balanay M.P. Enhancing dye-sensitized solar cells efficiency and stability with Ti-MOF-based quasi-solid-state electrolytes // 12th International Conference on Nanomaterials & Advanced Energy Storage Systems (INESS-2024). – Astana: Nazarbayev University, 2024. – August 7–9. 4. Ibrayeva A., Suleimenova D., Imanbekova Z., Abibulla U., Baptayev B., Balanay M.P. Covalent organic frameworks as electrolyte enhancers: a pathway to high-efficiency DSSCs // ACS Fall 2025 National Meeting. – Washington, DC, USA, 2025. – August 17–21 (digital participation). 5. Ibrayeva A., Imanbekova Z., Baptayev B., Balanay M.P. MOF-based electrolytes: a paradigm shift in enhancing the efficiency and stability of DSSCs // NU Annual Research Conference (NUARC-2024). – Astana: Nazarbayev University, 2024. – September 19–21. 6. Ibrayeva A., Suleimenova D., Baptayev B., Balanay M.P. Novel and cost-effective materials for dye-sensitized solar cells // The 2nd International Symposium on Emerging Materials and Devices (ISEMD-2024). – Astana: Nazarbayev University, National Laboratory Astana, 2024. – June 25–27.

Dissertation

List of Scientific Works

Consultant's Review

Foreign Consultant's Review

Conclusion of the Research Ethics Committee

Official Reviewer's Review

Official Reviewer's Review