Analytical model for the photocurrent-voltage characteristics of bilayer MEH-PPV/TiO2 photovoltaic devices

The photocurrent in bilayer polymer photovoltaic cells is dominated by the exciton dissociation efficiency at donor/acceptor interface. An analytical model is developed for the photocurrent-voltage characteristics of the bilayer polymer/TiO2 photovoltaic cells. The model gives an analytical expression for the exciton dissociation efficiency at the interface, and explains the dependence of the photocurrent of the devices on the internal electric field, the polymer and TiO2 layer thicknesses. Bilayer polymer/TiO2 cells consisting of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and TiO2, with different thicknesses of the polymer and TiO2 films, were prepared for experimental purposes. The experimental results for the prepared bilayer MEH-PPV/TiO2 cells under different conditions are satisfactorily fitted to the model. Results show that increasing TiO2 or the polymer layer in thickness will reduce the exciton dissociation efficiency in the device and further the photocurrent. It is found that the photocurrent is determined by the competition between the exciton dissociation and charge recombination at the donor/acceptor interface, and the increase in photocurrent under a higher incident light intensity is due to the increased exciton density rather than the increase in the exciton dissociation efficiency

A Novel Fluorescent Sensor for the Sensitive Detection of Mercury

AbstractMercury pollution is a widespread danger to human health and environment. To developed a effective method for mercury detecting is in high demand. This work demonstrated a novel bright fluorescent molecule DPDTC for the sensing of mercury. The approach was mainly based on the mercury-induced fluorescence turn-off of DPDTC. The probe was prepared by a simple method and exhibited high fluorescence. The fluorescence of DPDTC was very stable and immue to photobleaching. Results showed that DPDTC was a promising tool for mercury detection. Moreover, DPDTC could be immoblized on a paper to prepare an simple and portable sensor which expanded its real application

Cost-effective solid oxide fuel cell prepared by single step co-press-firing process with lithiated NiO cathode

A cost-effective cell fabrication process was developed for intermediate temperature solid oxide fuel cells (IT-SOFCs). Co-doped ceria Ce0.8Gd0.05Y0.15O1.9 (GYDC) was synthesized by carbonate co-precipitation method. Lithiated NiO was prepared by glycine-nitrate combustion method and adopted as cathode material for IT-SOFCs. Single cell was fabricated by one-step thy-pressing and co-firing anode, anode functional layer (AFL), electrolyte and cathode together at 1200 degrees C for 4 h. The cell presented decent performance and an overall electrode polarization resistance of 0.54 Omega cm(2) has been achieved at 600 degrees C. These results demonstrate the possibility of using lithiated NiO as cathode material for ceria-based IT-SOFCs and the development of affordable fuel cell devices is encouraged

Research progress of new composite nanomaterials for photocatalytic degradation in dye wastewater

Photocatalytic technology is an effective way to solve the two major problems of environmental problems and energy crisis in today's human society. Semiconductor materials were favored in early research. However, a single semiconductor photocatalyst has disadvantages such as poor response to visible light and easy recombination of electron-hole pairs. Photocatalytic technology has low efficiency in the application of dye wastewater degradation. Therefore, researchers have conducted in-depth studies on the new composite nanomaterials as photocatalysts to degrade dye wastewater. The research progress and main results of three new composite nanomaterials of graphene, metal organic framework, and carbon quantum dots for photocatalytic degradation of pollutants in dye wastewater were introduced in this article. According to the idea of design and upgrading of composite nanomaterials, the preparation methods of some new composite nanomaterials were briefly described, and the degradation efficiency of target pollutants was analyzed. By summarizing the performance of different photocatalytic materials to degrade pollutants in water, the future development trend was prospected. The future development trend and research focus of new composite nanomaterials in the direction of photocatalysis are targeted treatment of wastewater and industrialization

Analytical model for the photocurrent-voltage characteristics of bilayer MEH-PPV/TiO₂photovoltaic devices

<p>Abstract</p> <p>The photocurrent in bilayer polymer photovoltaic cells is dominated by the exciton dissociation efficiency at donor/acceptor interface. An analytical model is developed for the photocurrent-voltage characteristics of the bilayer polymer/TiO₂photovoltaic cells. The model gives an analytical expression for the exciton dissociation efficiency at the interface, and explains the dependence of the photocurrent of the devices on the internal electric field, the polymer and TiO₂layer thicknesses. Bilayer polymer/TiO₂cells consisting of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and TiO₂, with different thicknesses of the polymer and TiO₂films, were prepared for experimental purposes. The experimental results for the prepared bilayer MEH-PPV/TiO₂cells under different conditions are satisfactorily fitted to the model. Results show that increasing TiO₂or the polymer layer in thickness will reduce the exciton dissociation efficiency in the device and further the photocurrent. It is found that the photocurrent is determined by the competition between the exciton dissociation and charge recombination at the donor/acceptor interface, and the increase in photocurrent under a higher incident light intensity is due to the increased exciton density rather than the increase in the exciton dissociation efficiency.</p

Passivating Surface Defects of n-SnO2 Electron Transporting Layer by InP/ZnS Quantum Dots: Toward Efficient and Stable Organic Solar Cells

N-type tin oxide (n-SnO2) nanoparticle film has shown great potential as an electron transport layer (ETL) in fabricating highly efficient organic solar cells (OSCs) due to its low-temperature preparation and high electrical conductivity. However, surface defects on the n-SnO2 nanoparticles generated by the solution-processed approach seriously limit the performance of the OSCs with n-SnO2 ETL. InP/ZnS quantum dots (QDs) are employed to passivate the surface defects of n-SnO2 ETL, and an inverted OSC using PM6:Y6 as active layer achieves a power conversion efficiency (PCE) of 15.22%, much higher than that of a device based on pure n-SnO2 ETL (13.86%). The synergistic enhancement of the device open-circuit voltage (V-oc) and fill factor (FF) is attributed to the improved morphologies of PM6:Y6 layer on the QDs/ETL, increased charge extraction and collection efficiency, and decreased monomolecular recombination caused by the defect-trapped charge carriers in the solar cell. Moreover, the inverted device with n-SnO2/InP/ZnS QDs ETL show a much higher stability than that of the conventional PEDOT:PSS based one. This work presents a promising QDs passivation strategy on n-SnO2 ETL to develop efficient and stable OSCs

Improving Performance of Nonfullerene Organic Solar Cells over 13% by Employing Silver Nanowires-Doped PEDOT:PSS Composite Interface

Improving Performance of Nonfullerene Organic Solar Cells over 13% by Employing Silver Nanowires-Doped PEDOT:PSS Composite Interfac

Quantitative Determination of Ethylene Using a Smartphone-Based Optical Fiber Sensor (SOFS) Coupled with Pyrene-Tagged Grubbs Catalyst

For rapid and portable detection of ethylene in commercial fruit ripening storage rooms, we designed a smartphone-based optical fiber sensor (SOFS), which is composed of a 15 mW 365 nm laser for fluorescence signal excitation and a bifurcated fiber system for signal flow direction from probe to smartphone. Paired with a pyrene-tagged Grubbs catalyst (PYG) probe, our SOFS showed a wide linearity range up to 350 ppm with a detection limit of 0.6 ppm. The common gases in the warehouse had no significant interference with the results. The device is portable (18 cm &times; 8 cm &times; 6 cm) with an inbuilt power supply and replaceable optical fiber sensor tip. The images are processed with a dedicated smartphone application for RGB analysis and ethylene concentration. The device was applied in detection of ethylene generated from apples, avocados, and bananas. The linear correlation data showed agreement with data generated from a fluorometer. The SOFS provides a rapid, compact, cost-effective solution for determination of the fruit ethylene concentration dynamic during ripening for better fruit harvest timing and postharvest management to minimize wastage