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In this work, charge/energy transfer characteristics of PEDOT:PSS-TiO2 composites have been studied as a function of crystallite sizes of TiO2 nanocrystals annealed at different temperatures for its application in organic optoelectronic devices. From this we found that as the temperature increases energy transfer phenomenon dominates over charge transfer process. We raised the temperature from 200 to 400 °C. Charge transfer process observed at 200 °C and energy transfer process dominated at 400 °C.

InP quantum dots (QDs) and InP/ZnS core shell structures were synthesized using one pot hot injection technique. An increment in the PL intensity was seen after the growth of ZnS shell. A post synthesis HF treatment is given to the QDs in order to increase the PL intensity by removing surface defects. Humidity studies were done to observe the stability of InP QDs, treated InP and InP/ZnS QDs. An unusal increment in the PL intensity was observed for InP upon exposure to humidity. Within two weeks the PL intensity increased by 118 % without much change in the peak position. This can be attributed to the water molecules which get adsorbed on the surface of QDs and results in surface passivation. A similar trend was observed for treated InP QDs but in the second week, the PL increment was saturated and did not increase further. InP/ZnS showed a decrement in the PL intensity on exposure because it is robust to oxidation due to the formation of shell.

In recent years, kesterite structured Cu2ZnSn(S, Se)4 materials have attracted significant interest as second generation solar cell material. However, the capability of reproducibly synthesizing these nanocrystal (NC) inks with accurately controlled and specific compositions is very crucial for making efficient solar cell devices. In this work rod shaped CZTS nanoparticles are synthesized by cost effective and rapid hot injection technique using TOPO-TOP as capping ligand for various Zn/Sn precursor ratios. Since, for good solar cell device material (here, CZTS nanocrystals) higher zinc concentration are required so here, we varies zinc concentration and we find that mere increase in zinc amount in precursors for the synthesis of CZTS nanocrystals may not be necessarily advantageous for solar cell application. It should be optimized with respect to tin (Sn), phosphorus (P) and copper (Cu) for best PV properties and we find that incorporation of zinc into CZTS is higher in case where zinc amount is less in precursors. Different aspects of these nanorods are analyzed by EDAX, contact angle , transmission electron microscopy (TEM) and photoluminescence spectroscopy respectively.

TiO2 NPs synthesized via aqueous route shows better photocatalytic activity as compare to doped TiO2 NPs. The presence of dopants inhibits the recombination of exciton. The photocatalytic activity of the nanomaterial have been reduced because of less adsorption sites are available for MB dye due to increase surface coverage of nanomaterial by increase in Cr loading and thus less degradation is shown by doped material. Undoped TiO2 nanoparticles shows complete degradation of MB in 90 min, whereas doped TiO2 takes 120 min for complete degradation. The results suggested as higher concentration of dopant material leads to reduction in photocatalytic efficiency.

In the present study, the objective of this work has been two-fold: (i) To render CdSe QDs water-soluble for its possible application in biosensors , ligand-exchange process has been initiated. Here, the surface engineering of CdSe QDs synthesized with different hydrophobic ligands (TOPO/TOP, Oleic acid/TOP) has been done using organic primary aliphatic amine (butyl amine); and (ii) For different applications of hybrid organic MEH-PPV-inorganic CdSe composites in organic electronic devices such as efficient electroluminescent (OLED) and photovoltaic (OPV) devices, a suitable non-ligand purification process has been attempted. Here, the studies of hybrid nanocomposites demonstrate the dominance of mainly energy transfer between host polymer (donors) and guest as-synthesized CdSe nanocrystals (acceptors) for OLED applications and an enhanced charge transfer upon purification of CdSe QDs in their corresponding polymer nanocomposites for OPV applications respectively. The ease of removal of the ligands (TOPO/OA) from the surface of CdSe QDs either through direct ligand-exchange through Butyl-amine or through non-ligand exchange through purification process dictates its role in biosensors and in conjunction with polymer (MEH-PPV) in OLED and OPV devices respectively.

A comparative study on CIGSe nanocrystals prepared by two different ligands has been envisaged. This piece of study aims at comparing the properties obtained when toxic as well as non-toxic ligands are used for CIGSe, which is a potential photovoltaic material with performance at par with Si-based photovoltaics.

Chalcopyrite Cu (InxGa1−x) Se2 is a low-cost and potential alternative to present thin film silicon based photo-voltaic (PV) technology. Studies on nanocrystals of CIGSe prepared via colloidal route method with different capping agents, viz., oleylamine (OLA) and oleic acid (OA) have been done systematically. An exploration for binding abilities and plausible mechanism for the interaction between nanocrystals and capping agents employed has been envisaged.