This research aims to develop flexible tandem organic solar cells that could be used in building adaptive photovoltaics (PV). Organic solar cells (OSC) are composed of either polymers or dyes that are synthesized in bulk from simple ingredients that can form the light-absorbing layer in the PV cell. In January of 2020, a group of scientists from China published an article in Science Bulletin (DOI:10.1016/j.scib.2020.01.001) for a single-junctional organic solar cell based on a donor-acceptor copolymer (D18) as its donor material and a low-bandgap acceptor (Y6) based on fused-ring benzothiadiazole core unit which attained a photon-to-current conversion efficiency of 18.22 %. The highest efficiency for solution-process tandem solar cells is at 17.3% which utilizes PBDB-T:F-M and PTBY-Th:O6T-F polymers. With the advent of new D-A polymer types, this efficiency can be improved much further. The tandem approach is an effective way to address the issues plaguing OSC devices such as its low charge mobility of organic materials that limits the thickness of the active layer which affects its light absorption process. This also allows for widening the absorption range to more than 900 nm by properly matching the top- and bottom-active layers. This type of solar cell is a very good fit for building-integrated photovoltaics (BIPV) due to its flexibility, tunable transparency, and does not contain any heavy metals. It can also be easily fabricated using solution-based, low-temperature, roll-to-roll manufacturing method, using conventional printing techniques on flexible substrates which are the basic requirements for large-scale production.
Electrochromic materials are able to vary their coloration and transparency to solar radiation, in a reversible manner, when they are subjected to a small electric field (1–5 V). The main materials with electrochromic properties are metal oxides of transition, in particular WO3, MoO3, IrO2, NiO, and V2O5. The advantage of transition metal oxides is that it is very stable but it has a very limited range of available colors and brightness. On the other hand, electrochromic materials based on conjugated conducting polymers, wherein it can be easily tuned to a wide array of color combinations but suffers from stability even at ambient conditions. A material that can be both stable and be able to have a wide array of colors is the use of metal-organic frameworks (MOF). The first reported MOF as an electrochromic material was in 2013 using pyrazolate-based MOF. Since then, there are a number of reported MOF-based EC materials. This project searches for an effective ligand to the metal which includes bimetallic composition and host-guest assemblies.
B. Baptayev, D. Mustazheb, Z. Abilova, M.P. Balanay. Nanostructured flower-shaped CuCo2S4 as a Pt-free counter-electrode for dye-sensitized solar cells. Chem. Commun. 56 (2020) 12190. DOI:10.1039/D0CC04211K.
Various studies have been dedicated to the exploration and development of alternative types of solar cells with lower cost and better efficiency and stability compared to silicon photovoltaics. Nowadays, a lot of research is focused on the study of perovskite solar cells (PeSCs). Improvement of the photovoltaic conversion efficiency (PCE) in PeSCs has undergone an exponential increase throughout the years, from a mere 3.8% in 2009; it now has a PCE of 25%. Since the theoretical efficiency limit of PeSCs is at 31%, there is still a lot of room for improvements and this can be done by optimizing the absorber and hole transport material (HTM). The discovery of alternative HTMs is one of the major areas of research in PeSCs dedicated to the enhancement of device efficiency and stability. Spiro-OMeTAD, which is the commonly used HTM in PeSCs, possesses several disadvantages such as a complicated synthetic route, high cost, and low conductivity and hole mobility. Thus, the continued search for new HTM through a computational approach brings down the production cost.
The continued search for appropriate sensitizers to be used in dye-sensitized solar cells (DSSCs) is still under consideration since DSSCs offers a low-cost design with the relative ease of fabrication without the need for a glovebox as compared to the PeSCs. It is also currently being eyed as a possible energy source for low-energy devices used in Internet-of-Things.
L.L. Estrella, M.P. Balanay, D.H. Kim. Theoretical insights into D-D-p-A sensitizers employing N-annulated perlyne for dye-sensitized solar cells. J. Phys. Chem. A 122 (2018) 6328-6342.
M.P. Balanay, D.H. Kim. Strategic design of bacteriochlorins as possible dyes for photovoltaic applications. J. Phys. Chem. A 121 (2017) 6660.
M.A.B. Gapol, M.P. Balanay, D.H. Kim. Molecular engineering of tetraphenylbenzidine-based hole transport material for Perovskite solar cell. J. Phys. Chem. A 121 (2017) 1371.
L.L. Estrella, M.P. Balanay, D.H. Kim. The effect of donor group rigidification on the electronic and optical properties of arylamine-based metal-free dyes for dye-sensitized solar cells: A computational study. J. Phys. Chem. A 120 (2016) 5917.
This project is in collaboration with Dr. Annie Ng's research group (School of Engineering and Digital Sciences).
Metal-organic frameworks (MOFs) are widely studied as materials for gas storage, drug delivery, separation, catalysis, sensing, and various optoelectronic devices such as third-generation solar cells and electrochromic materials) due to their high surface area, good environmental stability, chemical tunability, and adjustable pore size. Thus further development of new metal - organic linker composition that is capable of efficient energy transfer is needed to push the efficiency and stability of perovskite solar cells and other optoelectronic devices such as sensors.
There is a constant need to develop a sensor for the detection of certain pollutants that are cheap, easily manufactured, and efficient. Chromium is the 21st most abundant element in the Earth's crust. It can exist primarily in two oxidation states, Cr(III) and Cr(VI). Cr(III) is considered to be involved in different metabolisms in the human body, while Cr(VI) is carcinogenic which causes various respiratory diseases for example bronchitis, asthma, and pneumonitis. Cr(VI) can be released to the environment from the cooling towers of various industries such as ferrochromium production, metallurgical industries, refractory production, electroplating, and combustion processes, especially from transportation sectors. Once released into the environment, it can come in contact with air particulates and also could end up in bodies of water, thus, there is a need to measure the extent of Cr(VI) pollution in the environment. The use of nanomaterials as fluorescent sensors is gaining much attention as compared to the traditional analysis methods (e.g. absorption spectroscopy, ion chromatography, atomic absorption spectroscopy, and electrochemical method) due to its better sensitivity, fast response time, and can be utilized in-situ analysis. Of the nanomaterials being considered, metal-organic frameworks (MOFs) and doped carbon nanodots (CDs) are the most promising materials that can be used as fluorescent sensors and environmental catalysts. Both materials can be produced from inexpensive precursors, facile synthesis, abundant, relatively stable, and not toxic.
E.K. Adotey, M. Amouei Torkmahalleh, M.P. Balanay. Zinc metal-organic framework with 3-pyridinecarboxaldehyde and trimesic acid as co-ligands for selective detection of Cr(VI) ions in aqueous solution. Methods Appl. Fluoresc. 8 (2020) 045007. DOI:10.1088/2050-6120/abb364.