Nanometer-scaled landscape of polymer: fullerene blends mapped with visibles-SNOM.

Bulk heterojunction is one key concept leading to breakthrough in organic photovoltaics. The active layer is expectantly formed of distinct morphologies that carry out their respective roles in photovoltaic performance. The morphology-performance relationship however remains stymied, because unequivocal morphology at the nanoscale is not available. We used scattering-type scanning near-field optical microscopy operating with a visible light source (visibles-SNOM) to disclose the nanomorphology of P3HT:PCBM and pBCN:PCBM blends. Donor and acceptor domain as well as intermixed phase were identified and their intertwined distributions were mapped. We proposed energy landscapes of the BHJ active layer to shed light on the roles played by these morphologies in charge separation, transport and recombination. This study shows that visibles-SNOM is capable of profiling the morphological backdrop pertaining to the operation of high performance organic solar cells.

Resolving Cross-Sensitivity Effect in Fluorescence Quenching for Simultaneously Sensing Oxygen and Ammonia Concentrations by an Optical Dual Gas Sensor.

Simultaneous sensing of multiple gases by a single fluorescent-based gas sensor is of utmost importance for practical applications. Such sensing is strongly hindered by cross-sensitivity effects. In this study, we propose a novel analysis method to ameliorate such hindrance. The trial sensor used here was fabricated by coating platinum(II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) and eosin-Y dye molecules on both sides of a filter paper for sensing O2 and NH3 gases simultaneously. The fluorescent peak intensities of the dyes can be quenched by the analytes and this phenomenon is used to identify the gas concentrations. Ideally, each dye is only sensitive to one gas species. However, the fluorescent peak related to O2 sensing is also quenched by NH3 and vice versa. Such cross-sensitivity strongly hinders gas concentration detection. Therefore, we have studied this cross-sensitivity effect systematically and thus proposed a new analysis method for accurate estimation of gas concentration. Comparing with a traditional method (neglecting cross-sensitivity), this analysis improves O2-detection error from -11.4% ± 34.3% to 2.0% ± 10.2% in a mixed background of NH3 and N2.

Polytriphenylamine and Poly(styrene-co-hydroxystyrene) Blends as High-Performance Anticorrosion Coating for Iron.

An electroactive polytriphenylamine (PTPA-C6) is blended with poly(styrene-co-hydroxystyrene) (PS-co-PHS) as coating layers to enhance protection efficiency of PTPA-C6 on iron substrate in 3.5% sodium chloride (NaCl) solution. Experimental results show that incorporation of hydroxyl group to the polystyrene not only increases the miscibility of PTPA-C6 with PS through the hydrogen bond formation, but also enhances the bonding strength between the polymer coating layer and iron substrate. These improvements lead to superior enhancement in anticorrosion performance of PTPA-C6, even after thermal treatment. Protection efficiency (PE) of PTPA-C6 increases from 81.52% of the PTPA-C6 itself to over 94.40% under different conditions (PEmax = 99.19%).