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Porphyrin sensitized solar cells (PSSC) has been successfully fabricated composed of graphene quantum dots (GQD) functionalized ZnO photoanodes, zinc tetrakis (4-carboxy phenyl)porphyrin (TCPPZn) as sensitizer and polypyrrole coated oxidised multiwalled carbon nanotubes (PPy/OMWCNT) as counter electrode. The effect of the concentration of GQD on the structural, morphological, photophysical and photovoltaic properties of GQD@ZnO, and GQD@ZnO/TCPPZn nanocomposites has also been investigated. Studies indicate that TCPPZn adsorbed on the surface on GQD@ZnO. Hot electron injection mechanism and multiple exciton generation from GQD to ZnO were mainly responsible for the photoexcitation response in PSSC. This study indicates that GQD can play role of sensitizer to some extent. The time decay measurements reveals the evidences of FRET mechanism, and synergistic interaction between GQD and TCPPZn. The J sc , Voc, PCE of the corresponding PSSC devices enhanced initially and then decreased. Among all the devices fabricated, the PSSC with a 40% amount of GQD (GQD@ZnO/TCPPZn 40%) attains the best performance with the J sc  = 10.1 mA/cm 2 , V oc  = 0.48, PCE = 2.45% FF = 0.507 higher than ZnO@TCPPZn device fabricated without GQD. Overall, this design provides a new concept for the development of photoanodes which derive better efficiency for dye sensitized solar cell (DSSC) and PSSC at economical low cost. [ABSTRACT FROM AUTHOR]

Conducting ternary photocatalyst, PEDOT@ZnO@GQDs with porous structure was synthesized using chemical oxidative polymerization. The fabricated photocatalyst was characterized by means of various spectroscopic techniques namely UV-Visible, FT-IR, XRD and the surface morphology was explored by SEM and TEM. Electro-catalytic activity of the photocatalyst has been studied by cyclic voltammetry. The kinetics of the photocatalytic degradation of the cationic dyes namely MB and R6G were studied in presence of PEDOT@ZnO@GQDs irradiated with UV light and solar light. The photocatalyst showed efficient photodegradation capacity due to the synergized effect of all three components namely PEDOT, ZnO and GQDs. The photocatalyst degraded the dyes in presence of solar light more efficiently. Photodegradation of the dyes follow first order kinetics, the kinetic parameters viz. rate constant and half life time period of the degradation of the dyes was evaluated through the plotted linear curves of concentration versus time. [ABSTRACT FROM AUTHOR]

Polypyrrole nanofibers/ meso-tetra(4-sulfonatophenyl)porphyrin/graphene quantum dots nanohybrid (PTG) was synthesized by a facile chemical oxidative reaction using persulfate salt of cetyltrimethylammonium cation ((CTA)SO) as the oxidative template. The facile formation and interactions among different constituents were established by FT-IR, UV-Vis, XRD and XPS studies. Morphological analysis was carried out by SEM and HRTEM showing polypyrrole nanofibers (PNF) to be formed with diameters in the range of 29-57 nm and HRTEM micrographs depicted the intercalation of meso-tetra(4-sulfonatophenyl)porphyrin (TSPP) and graphene quantum dots (GQDs) with PNF. The electrical conductivity of PNF and PTG was evaluated using four-probe conductivity measurement. Electrochemical activity of PNF and PTG deposited on indium tin oxide (ITO) electrode was demonstrated using cyclic voltammetry with Fe(CN) as the redox species. PTG electrode displayed an enhanced voltammetric response vis-à-vis PNF due to the synergistic effect of PNF, TSPP and GQDs resulting in an increased electroactive area beneficial for a sensing probe. Further, the PTG electrode was checked for its capability to simultaneously detect Cd and Pb in aqueous solution by differential pulse voltammetry (DPV). [ABSTRACT FROM AUTHOR]

Quantum dot sensitized solar cell based on poly(3-methoxythiophene) (PMOT)@CdSe@ZnO core shell nanostructure were synthesized where PMOT serves as hole transport material, CdSe acts as a photosensitizer which enhances visible range absorption and also helps in injection of electrons from PMOT to ZnO where ZnO provides channel for efficient electron transport. The properties of the device were assessed with and without CdSe quantum dots and effect of annealing was also observed on the device. After the addition of CdSe QDs, the visible light absorption of PMOT@ZnO was enhanced due to increase in surface area. PMOT@CdSe@ZnO exhibited dual emission, where CdSe and ZnO exhibited visible and UV emission respectively. The interface formed between PMOT and CdSe improves the charge separation. The better photovoltaic measurement of PMOT@CdSe@ZnO over CdSe@ZnO indicates that PMOT efficiently dissociate excitons at interface and suppress the interfacial charge recombination. A power conversion efficiency of 0.989% was attained for the device PMOT@CdSe@ZnO with V oc =0.56 V and J sc =2.5 mA/cm 2 . Upon annealing, the efficiency of the device was enhanced to 1.1609% with V oc =0.58, J sc =3.2 mA/cm 2 . [ABSTRACT FROM AUTHOR]

The optoelectronic properties of P3HT–CdSe nanocomposites prepared by insitu chemical oxidative polymerization were studied. CdSe QDs were synthesized by hot injection method using tri octyl phosphine oxide (TOPO) as capping ligand whereas the P3HT polymer was prepared by chemical oxidative polymerization. FTIR studies confirmed the regioregularity of the P3HT and revealed the chemical interaction of P3HT and CdSe in nanocomposite. Absorption studies showed blue shift for the nanocomposites as compare to pristine P3HT, the electron transfer from conducting polymer to the CdSe was detected by the measurements of quenching of photoluminescence from conducting polymer after the addition of semiconductor nano crystals which confirmed that an optimum amount of nanoparticles provide networking in hybrid composites. The optimal result for device prepared by P3HT–CdSe nanocomposites was open circuit voltage ( V oc ) 0.5, short circuit current density ( J sc ) 0.66, Fill factor (FF) 0.6855 and efficiency ( η ) 0.22%. [ABSTRACT FROM AUTHOR]