Category Archives: Research

Solar Cells

There is a large social need for renewable energy in the country especially solar energy. With about 300 clear, sunny days in a year, India’s theoretically calculated solar energy incidence on its land area alone is about 5,000 trillion kilowatt-hours (kWh) per year (or 5 EWh/yr). The development of next generation, high efficiency and stable solar cells will enable us to provide power in remote areas of the country and therefore will have a large social and technological impact. The recent emergence of efficient solar cells based on organic/inorganic lead halide perovskite absorbers promises to transform the fields of dye-sensitized, organic, and thin film solar cells.

Photophysics Study in Perovskite Solar Cells:

Our achievement is the fabrication of all air processed and stable perovskite solar cells upto 15% efficiency and we have studied their detailed morphology optimization and photophysics. We have designed and reported a novel method of controlling surface roughness in perovskite solar cells named dual solvent elimination method which leads to larger grain size and better crystallinity at room temperature. We achieved much higher crystallinity and uniformity in lead and lead free perovskite film by solvent annealing method.

Large Area and Stable Perovskite Solar Cells:

Metal halide perovskites attract considerable attention for application in photovoltaic cells. We focus on the development of large area, high efficiency and stable perovskite solar cells involving various device engineering protocols for morphology optimization and scalable manufacturing of air-stable solar cells. We study charge carrier dynamics by various techniques like transient absorption spectroscopy, transient PL spectroscopy, confocal microscopy, temperature dependent photo luminescence spectroscopy, impedance spectroscopy and c-AFM. 

Carrier Dynamics in Two-Dimensional Perovskite:

Two-dimensional (2D) Ruddlesden–Popper perovskite materials gained importance due to its higher photo stability, when compared to its three-dimensional (3D) counterpart. In our group, we study the exciton binding energy, charge carrier recombination, charge carrier transport, and conductivity as a function of different organic and inorganic spacer cations chain length in these 2D quantum wells. We probe the fundamental photophysics in these 2D perovskite by different advanced spectroscopic techniques like transient spectroscopy and terahertz spectroscopy.

Perovskite Single Crystal:

Perovskite single-crystal, which exhibit exceptionally low trap density and nearly perfect transnational symmetry, are believed to achieve the highest performance of perovskite-based optoelectronic devices. Here, fabricate several lead free perovskite single crystals for photodetector and X-Ray detector application. We also study their charge carrier dynamics by temperature dependent photo luminescence spectroscopy, femtosecond transient absorption and photo luminescence spectroscopy, impedance spectroscopy, and electron spin resonance spectroscopy.

Singlet Fission:

Singlet exciton fission-sensitized solar cells have the potential to exceed the Shockley-Queisser limit by generating additional photocurrent from high-energy photons. Here, our group will try to understand the underlying photophysics behind singlet fission in molecular systems and nanoparticles on sub 100s timescale.

Organic Nanoparticles based Solar Cells:

We have fabricated nanoparticles of donor polymers (low bandgap polymers like PTB7 and PCPPDT) and fullerene acceptor molecules (like PCBM) by applying mini-emulsion techniques in the presence of various cationic and anionic surfactants and studied their morphology and photophysics. Mobility of these nanoparticles was measured and these nanoparticles with opposite charges were self-assembled to control exciton diffusion length. In addition to studying photophysics and morphology, we demonstrated that the self-assembly of oppositely charged nanoparticles is a promising approach to design efficient bulk heterojunction.

Dye Sensitized Solar Cells:

We use different novel dyes as sensitizers and novel engineered carbon nanomaterials as counter electrode in DSSC. Recently, we fabricated DSSCs with four naturally occurring anthocyanin dyes extracted from naturally found fruits/juices (viz., Indian jamun, plum, black currant, and berries) as sensitizers.

Related Publications:

[1] “Effect of size and charge asymmetry on aggregation kinetics of oppositely charged nanoparticles”, Kulveer Singh, Anubhav Raghav, Prateek K Jha, Soumitra Satapathi, Just Accepted, Nature Scientific Reports, 9 (1), 3762, 2019.

[2] “Charge Carrier Dynamics Study and Morphology Optimization in Solvent Annealed CH3NH3PbI3 Perovskite for Air Processed Stable Solar Cell Application”, Anubhav Raghav, Shivam Singh, Dhanashree Moghe, Shailendra Sharma, Dinesh Kabra, Soumitra Satapathi, Chemical Physics, https://doi.orgmphys/10.1016/j.che.2019.110408, 2019.

[3] “Morphological and photophysical study in hybrid ternary organic nanoparticles blends”, Anubhav Raghav, Mrinmoy K Chini, Amar Bheemaraju, Rajashik Paul, Soumitra Satapathi, Chemical Physics, 525, 110388, 2019.

[4] “Temperature Assisted Nucleation and Growth to Optimize Perovskite Morphology at Liquid Interface: A Study by Electrochemical Impedance Spectroscopy”, Priya Srivastava, Anukul Prasad Parhi, R Ranjan, Soumitra Satapathi, Monojit Bag, ACS Applied Energy Materials, 4420–4425, 1, 9, 2018.

[5] “Local optoelectronic characterization of solvent annealed lead-free bismuth-based perovskite films”, Jill Wenderott, Anubhav Raghav, Max Shtein, Peter Green, Soumitra Satapathi, , Langmuir, 7647-7654, 34, 26, 2018.

[6] Controllable Bulk Heterojunction Morphology by Self-Assembly of Oppositely Charged Nanoparticles”,Kulveer Singh, Prateek K. Jha, and Soumitra Satapathi, Journal of Physical Chemistry C, 121, 16045−16050, 2017.

[7]“Controlling morphology of CH3NH3PbI3 perovskite film by dual solvent elimination method”, Anubhav Raghav, Shivam Singh, Shailendra Kumar Sharma, Kabra Dinesh, Monojit Bag, Soumitra Satapathi, Nano-Structures & Nano-Objects, 12, 106–112, 2017.

[8] “Synthesis of Nanoparticles of P3HT and PCBM for Optimizing Morphology in Polymeric Solar Cells”, Soumitra Satapathi, Hardeep Singh Gill, Lian Li, Lynne Samukeson, Jayant Kumar,* Ravi Mosurkal, Applied Surface Science, 323, 3–18, 2014.

[9] “Photophysical Study of P3HT/NDI Based Hybrid Nanoparticles”, Soumitra Satapathi, Mijanur Rahaman Molla, Santanu Bhattacharya, Suhrit Ghosh and Amitava Patra, European Journal of Physics D, , 2014, 68:350, 2014.

[10] “Effect of functional groups on sensitization of dye-sensitized solar cells (DSSCs) using free base Porphyrins”, Nivedita Choudhary, Nipun Sahwney, Anubhav Raghav, M. Sankar, Soumitra Satapathi, Journal of Porphyrins and Phthalocyanines, 21, 222, 2017.

[11] “Utilization of Naturally Occurring Dyes as Sensitizers in Dye Sensitized Solar Cells.” Nipun Sawhney, Soumitra Satapathi, IEEE Photovoltaics, 7, 2, 539-544, 2017. [Featured in Nature Asia, PTI, Quartz, BBC, Chemical Today].

Microfluidics

Microfluidics is both the science which studies the behaviour of fluids through micro-channels, and the technology of manufacturing micro-miniaturized devices containing chambers and tunnels through which fluids flow or are confined.
Microfluidics deal with very small volumes of fluids, down to femtoliters (fL) which is a quadrillionth of a liter. Fluids behave very differently on the micrometric scale than they do in everyday life: these unique features are the key for new scientific experiments and innovations.

At Satapathi Lab, we are perfecting 3D Printing based fabrication of microfluidic devices for making Lab-On-Chip devices for Point-of-Care applications and the trace detection of compounds, biomarkers.


(a) DIAGNOSIS-ON-CHIP


Microfluidics-based diagnostics is an emerging field and is preferred over conventional diagnostic systems because of the faster sample processing, lower reagent volume per test and the fact that it allows for Point-of-Care (POC) diagnosis in inaccessible areas. We design POC diagnosis devices with integrated optical and electronic sensors for both pathogenic diseases (M.Tb, Dengue, Malaria etc.) and non-pathogenic diseases like various forms of Cancer. ELISA and MTT Assays are some of the commonly used diagnostic methodologies in laboratories and we work towards the development of their ‘On-Chip’ versions which are more sensitive than the conventional assays, but at the same time are cost-effective and could be deployed in remote locations.

3D Printed Microfluidic On-Chip Assay ©SatapathiLab

(b) DROPLET MICROFLUIDICS


Droplet-based microfluidic systems have been shown to be compatible with many chemical and biological reagents and capable of performing a variety of “digital-fluidic” operations that can be rendered programmable and reconfigurable. This platform has dimensional scaling benefits that have enabled controlled and rapid mixing of fluids in the droplet reactors, resulting in decreased reaction times. In addition to using the droplets as microreactors ranging from the nano- to femtoliter range; we are using the droplet-based systems to directly synthesize nano-particles and encapsulate many biological entities for biomedicine and solar, and sensor applications.

3D Printed Droplet Generator ©SatapathiLab

(c) ORGAN-ON-CHIP


The concept of Organ-on-Chip deals with bio-mimicry of various human organs viz. lungs, gut, heart etc. into their on-chip analogues which will not only allows us to study the behaviour of various tissues under cyclic stress environments present in organs like lung and heart, but also to test the kinetics of various drugs and proliferation of infectious diseases under such environments. This is one of the most challenging fields in biotechnology since it not only involves designing intensive microfluidic networks similar to arteries and veins in the human body but also bio-printing of cells into a mechanically stable structure capable of developing into mature tissues.

3D Cell matrix in PDMS ©SatapathiLab


Optical Sensors

Sensing chemical warfare like 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT) are of significant interest for civilian and military applications as well as for environmental reason. The nitroaromatics in the form of plastic explosives, nerve gas, and toxic spills pose significant threat to civilian and military safety. The threat has grown especially during the last two decades due to the enhanced globalization and mobility of the society at large. In addition, TNT and other nitroaromatics in groundwater and seawater have been classified as potential environmental hazards. Therefore, it is of utmost importance to develop sensor which can detect them with high sensitivity and selectivity. 

FRET based sensor for nitroaromatics detection:

We have developed a Fluorescence Resonance Energy Transfer (FRET) based sensor system for highly sensitive detection of nitro-aromatic compounds. The sensor system is composed of polymer, small molecule and nanoparticles as donor and acceptor molecule respectively. Primarily, the fluorescence of the donor material is quenched by non-radiative energy transfer to acceptor which occurs when the two molecules are within FRET distance scale. The efficiency of this FRET process is calculated. We have observed a noticeable decrease in the FRET signal when nitroaromatics viz. 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT) is gradually introduced into the sensor system. Fluorescence lifetime was measured to validate the efficacy of the energy transfer process in sensor system. The mechanistic details of molecular interactions was established by infrared spectroscopy and UV-vis absorption spectroscopy. Finally, a prototype sensor was fabricated for field use.

FRET System for the Detection of Heavy Metal Pollutants in Aqueous System:

Heavy metal ions including mercury (Hg2+) and lead (Pb2+) pollution poses severe health and environmental and health hazards. A highly sensitive and environment friendly multimodal nanosensor encompassing magnetic and fluorescent functionality is designed for the simultaneous detection and removal of mercury ion in water. A significant fluorescence quenching is observed with the increasing concentration of Hg2+ with low limit of detection. The detected analyte is successfully removed with the help of a bar magnet leaving no residual secondary pollution. The details mechanism of sensing is investigated. The simple and elegant material chemistry provide a facile route towards field based mercury sensor development in the future.

Optical Sensing with Terahertz Spectroscopy:

The identification of gases is of great interest in many fields. e.g. the analysis of human breath has a large medical potential because it contains hundreds of volatile organic compounds (VOCs) that can be attributed to certain physiological processes and pulmonary as well as non-pulmonary diseases (e.g. chronic obstructive pulmonary disease (COPD) and diabetes, respectively). Further interests arise from the detection of toxic industrial chemicals (TICs) or security-relevant gases (e.g. explosives).

With Terahertz/millimeter wave spectroscopy, gases are identified with high sensitivity, high specificity and high selectivity due to strong rotational transitions of the molecules that exhibit distinct spectral fingerprints. Our research involves the development of a breath gas sensor based on a terahertz/millimeter wave gas spectrometer around 250 GHz which requires high sensitivity detection with gas concentration levels below 1 part per million.

List your best Papers in the Optical Sensing Research Area:

[1] “Multimodal Fluorescent Polymer Sensor for Highly Sensitive Detection of Nitroaromatics”, Vishal Kumar, Binoy Maity, Mrinmoy K Chini, Priyodarshi De, Soumitra Satapathi, Nature Scientific Reports, 9(1), 7269, 2019. [Featured in DST, PTI, Economic Times]

[2] Mrinmoy K Chini, Vishal Kumar, Ariba Javed, Soumitra Satapathi, Graphene quantum dots and carbon nano dots for the FRET based detection of heavy metal ions, Nano-Structures & Nano-Objects, 19,100347, 2019.

[3] “Design of a novel FRET based fluorescent chemosensor and their application for highly sensitive detection of nitroaromatics”, Payal Taya, Binoy Maiti, V Kumar, Priyodarshi De, Soumitra Satapathi, Sensors and Actuators B: Chemical, 255, 3, 2628-2634, 2018.

[4] “Highly sensitive detection and removal of mercury ion using a multimodal nanosensor”, Soumitra Satapathi, Vishal Kumar, Mrinmoy Kumar Chini, Rajesh Bera, Krishna Kanta Halder, Amitava Patra,  Nano-Structures & Nano-Objects, 120-126,16, 2018.

Water Remediation

Water pollution due to the indiscriminate disposal of industrial and domestic wastes poses a serious environmental hazard both nationally and internationally. Worldwide, 780 million people still lack easy access to clean potable water. According to a recent report, it is estimated that around 37.7 million Indians are affected by waterborne diseases annually, with an estimated 1.5 million children dying from diarrhea alone, and 73 million working days are lost due to waterborne diseases each year. Our lab is continuously working on industrial waste water remediation and development of a low cost water filter.

Graphene Nanofiber for Photocatalytic Activity:

Recently, we reported the graphene-oxide-based hydrophobic nanofibers fabricated using electrospinning technique for photocatalytic degradation of Rhodamine 6G dye under natural sunlight illumination. The synthesized nanofibers were characterized using X-ray diffraction, EDX, field emission scanning electron microscopy and FTIR spectroscopy. These large-area reusable graphene oxide nanofibers provide a scalable and novel route for photocatalytic degradation of carcinogenic dyes from industrial water.

(b) Graphene Xerogel for Heavy Metal Ion Detection:

Recently, we fabricated graphene-based 3D porous xerogel through molecular self-assembly of graphene oxide on chitosan matrix and its application in removal of different heavy metal ions from wastewater was investigated. The synthesized xerogel was characterized through FTIR, SEM, XRD and BET surface area analysis. Heavy metal ions, including Pb(II), Cd(II), and Hg(II), were removed from wastewater using this graphene-chitosan (GO-Cs) xerogel and the removal efficiency was monitored through inductively coupled plasma mass spectrometry (ICP-MS).

(c) Development of Low Cost Water Filter:

Recently, we have synthesized highly porous graphene like material in bulk amount in extreme low cost from grass. We have filed the invention disclosure for the same. A low cost water filter is being built with these materials along with activated charcoal which is expected the lower the cost significantly.

Related Publications

[1]. “Reusable graphene oxide nanofibers for enhanced photocatalytic activity: a detailed mechanistic study”, Shailendra Kumar Sharma, Shivali Sokhi, Chandrajit Balomajumder, Soumitra Satapathi, , Journal of Materials Science, 52, 9,5390–5403, 2017.

[2]. “Graphene-Based 3D Xerogel as Adsorbent for Removal of Heavy Metal Ions from Industrial Wastewater”, Purnendu, Soumitra Satapathi, Journal of Renewable Materials, 5, 2, 96-102, 2017.