Suman Kushwaha

Bio: Suman Kushwaha is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Dye-sensitized solar cell & Auxiliary electrode. The author has an hindex of 4, co-authored 4 publications receiving 108 citations.

Novel ethynyl-pyrene substituted phenothiazine based metal free organic dyes in DSSC with 12% conversion efficiency

Abstract: Six new dyes based on phenothiazine conjugated to an ethynyl-pyrene moiety are synthesized and characterized. Dye-sensitized solar cells are fabricated using these dyes with and without a co-adsorbent, chenodeoxychloicacid. Simple molecular engineering around the phenothiazine moiety enabled a maximum of 12% photoconversion efficiency with one of the dyes.

A DSSC with an Efficiency of ∼10 %: Fermi Level Manipulation Impacting the Electron Transport at the Photoelectrode‐Electrolyte Interface

Abstract: In the literature, many studies pertain to gold (Au) nanoparticles, (NPs) incorporated dye-sensitized solar cells (DSSCs) were reported due to the beneficial effect of the surface plasmon polaritons originating from the Au NPs on the DSSC performance. Thiolated Au quantum dots and dye based DSSCs was explored recently, wherein the Au cluster act both as sensitizer and voltage booster by enhancing the quasi-Fermi level of TiO2. There is a knowledge gap on effect of thiolated Au NPs on DSSC performance. In this study, we have demonstrated Fermi level equilibration between the TiO2 and thiolated Au NPs. Thiolated Au NPs blocks the back electron transfer at the thiolated Au NPs-electrolyte interface thereby improving the open circuit voltage and efficiency of DSSCs. We have also shown beneficial effect of WO3–TiO2–thiolated Au NPs interface in enhancing the DSSC performance significantly in comparison to that of sole TiO2 based DSSC. For the DSSC cell: FTO/WO3/TiO2-Au-thiolated/N719, an efficiency of 9.9 % is achieved (JSC = 17.4 mA cm−2, VOC = 0.820 V and FF=0.70).

Research progress on photosensitizers for DSSC

Abstract: Dye sensitized solar cells (DSSC) are considered one of the most promising photovoltaics technologies alternative to the traditional silicon based solar cells because of their compatibility with low cost manufacture methodologies, their peculiar optical and mechanical properties and their high indoor efficiency. Photosensitizers represent one of the most important part in a DSSC device and probably the most thoroughly investigated in the last twenty years, with thousands of dyes that have been proposed and tested for this kind of application. In this review we aimed to give an overview of the three main classes of DSSC photosensitizers, namely ruthenium (II) polypyridyl complexes, Zn-porphyrin derivatives and metal free organic dyes. After a brief introduction on the architecture and operational principles of a DSSC and on the state of the art of the other main components of this kind of device, we focused our discussion on photosensitizers. We defined the several requirements DSSC photosensitizers should fulfil and provided an excursus about their historical development along the years; by examining specific dyes reported in the literatures, we attempted to highlight the molecular design strategies that have been established for the optimization of their performance in actual devices both for what concerns efficiency (that recently reaches an outstanding 14.3 %) and operational stability. We finally discussed, in the last section, about the possible future developments of this intriguing technology.

Prediction of Second-Order Nonlinear Optical Properties of D–π–A Compounds Containing Novel Fluorene Derivatives: A Promising Route to Giant Hyperpolarizabilities

Abstract: Herein, first attempt has been made to utilize fluorene-based dye-sensitized solar cell (DSSCs) dye JK-201 as potential nonlinear optical (NLO) material and for the theoretical designing of novel NLO chromophores JK-D1–JK-D12. DFT/TDDFT calculations were performed to compute the effect of π-linkers and acceptors-steered modulation on electronic, photophysical and NLO properties of JK-201 and JK-D1–JK-D12. Results illustrate that computed λmax (484.74 nm) and experimentally calculated λmax (481 nm) of JK-201 was found in good agreement. Maximum red shifted absorption spectrum was observed in JK-D12 with 599.38 nm. JK-D1–JK-D12 showed narrow energy gap and broader absorption spectrum as compared to JK-201. NBO analysis confirmed the formation of charge separation state due to robust range of electrons/charge transfer from donor to acceptor via π-bridge. Giant NLO response was observed in all compounds. Particularly, JK-D12 displayed surprisingly large 〈α〉 and βtot computed 1376.74 (a.u.) and 405,731.84 (a.u.) respectively. Although literature is flooded with D–π–A compounds investigated for their DSSCs properties, but research reports on their NLO properties and utilization as NLO materials are completely deserted. Our research will open new horizons to explore DSSCs materials for NLO applications. This theoretical framework also exposed that fluorene-substituted chromophores are excellent NLO candidates for modern hi-tech applications.

Novel ethynyl-pyrene substituted phenothiazine based metal free organic dyes in DSSC with 12% conversion efficiency

Abstract: Six new dyes based on phenothiazine conjugated to an ethynyl-pyrene moiety are synthesized and characterized. Dye-sensitized solar cells are fabricated using these dyes with and without a co-adsorbent, chenodeoxychloicacid. Simple molecular engineering around the phenothiazine moiety enabled a maximum of 12% photoconversion efficiency with one of the dyes.

Theoretical and Conceptual Framework to Design Efficient Dye-Sensitized Solar Cells (DSSCs): Molecular Engineering by DFT Method

Abstract: Herein, eight new donor-π-acceptor organic dyes namely M1–M8 have been theoretically investigated for their potential in optoelectronic properties. The M1–M8 were designed through structural modification of π-conjugated bridge of reference reported molecule IC2. The designed molecules contain Indolo[3,2,1-jk]carbazole as core donor unit and end capped cyanoacrylic acid as acceptor unit. DFT and TDDFT calculations using B3LYP, CAM-B3LYP, ωB97XD and M062X functional were performed to evaluate the photophysical and photovoltaic properties. Results indicate that HOMO–LUMO energy gaps in M1–M8 have been found smaller than IC2. Among all, M7 is a material with lowest energy gap 2.61 eV, red shifted absorption wavelength value 436 nm. Results of the calculated redox potential of the ground state, vertical excitation energy of the dye, oxidation potential of the dye in the excited state, free energy change for electron injection, dye regeneration and open circuit photovoltage and light harvesting efficiency indicates that π-bridges in M1–M8 would show better power conversion efficiency than IC2. Especially, dye M7 with π-bridge 5-(thiazol-5yl)thiazole is found to be the most promising candidate for highly effective DSSCs properties. This theoretical framework may provide new ways for experimentalists to design high-performance DSSCs materials for optoelectronic applications.