Transition metal dichalcogenides
In TMDCs family, especially MoS2 and WS2 are the emerging 2D materials for various applications in electrical, catalytic and optical, due to their direct band gap semiconducting nature. Monolayer MoS2/WS2 have shown are the promising candidate due to easy band gap tuning with layer number. We successfully synthesized the in-plane and edge oriented MoS2 structure. Currently, we are working on the effect of orientation of TMDCs structures on the various mentioned applications.
Solar cell photovoltaics
Earth receives more energy from the sun in a given day than the energy consumed by the total world population in a year. For the future energy requirement of the mass population, energy harvesting through solar photo voltaics is on the leading edge among other renewable energy resources. The main challenges in marketing solar cell technology are the high manufacturing costs and the non-availability of novel techniques to enhance the cell efficiency. The main expenditure is the cost of the materials used for the solar cell fabrication. It is well documented that 40% of the cost of solar cell fabrication is in the materials side, and hence any reduction in the quantity of material can lead to a drop in the cost of solar cells. Thin film solar cell is a leap forward in this area to cut down the costs effectively. CZTS is the most seeking absorber material for thin film solar cells. In addition to being economically and ecologically viable, CZTS possess desirable properties like p-type conductivity, large absorption coefficient α >104 cm-1and band gap of around 1.5 eV which is very close to the theoretical optimum value.
The potential of CZTS was recognized by Ken taro Ito in 1988 and CZTS thin film was fabricated by atom beam sputtering and demonstrated a photo voltaic effect. In the past few years there has been a tremendous growth in the number of publications relating to CZTS with large number of techniques for its synthesis and characterization. Solar cells employing Cu2ZnSnS4(Se)4 absorber layer showed efficiency up to 12.7% which is much lower than its SQ limit. The major challenges in CZTS based solar cells are narrow its phase stability which makes secondary phases easy to form during the growth process, inefficient carrier management and photon management.
Solar Blind Photodetectors
Next generation photo detector would be using wide-band gap semiconductor which can work in an intense environment without any interference from background surroundings.UV photo detectors fabricated from wide band-gap semiconductors such as β-Ga2O3is the most promising material among wide band gap semiconductors like AlGaN, ZnMgO, BN and diamond. They have attained an increasing attention in recent years because of their high thermal and chemical stability as well high tolerance of electric field determining its possibility to work in hostile environments.
Development of high performance TCO’s
Transparent conducting oxides are a special class of material which exhibit a remarkable good electrical conductivity (~103S/cm) like metals and remarkable good optical transmittance (>80%) in visible and IR region. Generally oxides are assumed to be an insulator due to their large band gap but TCO are exceptional oxides. Due to this idiosyncratic property, they are devastatingly used in Research and industry.
So far they are generally found in crystalline nature but recently a new group of conventional TCOs are proposed which are amorphous in nature having comparable optoelectronic properties as crystalline TCOs giving advantage of being flexible as well. Easy and cheap fabrication technique is an essential step to make them usable widely. Physical vapor deposition (PVD) techniques are used at a large scale in the fabrication of TCO thin films which used as an electrode in passive device like photovoltaic, organic light emitting diode (OLED) and active layer in active devices like thin film transistor (TFT).