No abstract

A highly efficient acceptor material for organic solar cells (OSCs)--based on perylene diimide (PDI) dimers--shows significantly reduced aggregation compared to monomeric PDI. The dimeric PDI shows a best power conversion efficiency (PCE) approximately 300 times that of the monomeric PDI when blended with a conjugate polymer (BDTTTT-C-T) and with 1,8-diiodooctane as co-solvent (5%). This shows that non-fullerene materials also hold promise for efficient OSCs.

Since the wide adoption of liquid chromatography/tandem mass spectrometry (LC/MS/MS), the ion suppression/enhancement phenomenon is the latest barrier to high-throughput analysis. This consequence of a nonoptimized analytical method can lead to adverse effects during quantitation (i.e. poor accuracy and precision). Previous papers have reported that ion suppression is a direct result of endogenous material present in biological samples. However, in the case of a solid-phase liquid chromatography/tandem mass spectrometry (SPE/LC/MS/MS) system, the measured result is the combination of several operating conditions and parameters. Little has been done to effectively monitor and/or choose optimized conditions for the complete sequence of extraction, clean up, separation and analysis. This paper describes a simple setup for quantification of ion suppression/enhancement. Several mobile phase additives, ion-pairing agents and SPE extracts were measured and compared against a standard reference. The results demonstrated that a clean up of plasma extracts based on ion exchange leads to minimal ion suppression/enhancement for the compounds that were investigated.

A solution-processed diketopyrrolopyrrole (DPP)-based small molecule, namely BDT-DPP, with broad absorption and suitable energy levels has been synthesized. The widely used solvents of chloroform (CF) and o-dichlorobenzene (o-DCB) were used as the spin-coating solvent, respectively, and 1,8-diiodooctane (DIO) was used as additive to fabricate efficient photovoltaic devices with BDT-DPP as the donor material and PC71BM as the acceptor material. Devices fabricated from CF exhibit poor fill factor (FF) of 43%, low short-circuit current density (Jsc) of 6.86 mA/cm(2), and moderate power conversion efficiency (PCE) of 2.4%, due to rapid evaporation of CF, leading to poor morphology of the active layer. When 0.3% DIO was added, the FF and Jsc were improved to 60% and 8.49 mA/cm(2), respectively, because of the better film morphology. Active layer spin-coated from the high-boiling-point solvent of o-DCB shows better phase separation than that from CF, because of the slow drying nature of o-DCB, offering sufficient time for the self-organization of active-layer. Finally, using o-DCB as the parent solvent and 0.7% DIO as the cosolvent, we obtained optimized devices with continuous interpenetrating network films, affording a Jsc of 11.86 mA/cm(2), an open-circuit voltage (Voc) of 0.72 V, an FF of 62%, and a PCE of 5.29%. This PCE is, to the best of our knowledge, the highest efficiency reported to date for devices prepared from the solution-processed DPP-based small molecules.

No abstract

The potential response behaviour of a chloride doped polypyrrole (PPy) polymer film electrode to chloride ion in solution has been examined. The effect of the polymerisation conditions on the characteristics of the potential response and response mechanism is discussed. A chloride ion-selective electrode based on a conducting PPy polymer film was prepared with a potential response slope of 58-60 mV (pCI-)-l and a detection limit of 3.5 x 10-5 M of CI-. The optimum conditions for the preparation of the electrode were: pyrrole (Py), 0.05-0.2 M; UCI, 0.1-1 M; scan range for electrochemical polymerisation, 0.5-1.2 V; polymerisation time, 10-30 min; and scan rate, 20-100 mVs-1. The chemical sensor has a fast response, a low resistance, is easy to prepare and is not susceptible to poisoning.

No abstract

A non-fullerene, all-small-molecule solar cell (NF-SMSC) device uses the blend of a small molecule donor and a small molecule acceptor as the active layer. Aggregation ability is a key factor for this type of solar cell. Herein, we used the alkylthienyl unit to tune the aggregation ability of the diketopyrrolopyrrole (DPP)-based small molecule donors. Replacing two alkoxyl units in BDT-O-DPP with two alkylthienyl units yields BDT-T-DPP, and further introducing another two alkylthienyl units into the backbone produces BDT-T-2T-DPP. With the introduction of alkylthienyl, the backbone becomes twisted. As a result, the ππ-stacking strength, aggregation ability, and crystallite size all obey the sequence of BDT-O-DPP > BDT-T-DPP > BDT-T-2T-DPP. When selected a reported perylene diimide dimer of bis-PDI-T-EG as acceptor, the best NF-SMSC device exhibits a power conversion efficiency of 1.34, 2.01, and 1.62%, respectively, for the BDT-O-DPP, BDT-T-DPP, and BDT-T-2T-DPP based system. The BDT-T-DPP/bis-PDI-T-EG system yields the best efficiency of 2.01% among the three combinations. This is due to the moderate aggregation ability of BDT-T-DPP yields moderate phase size of 30-50 nm, whereas the strong aggregation ability of BDT-O-DPP gives a bigger size of 50-80 nm, and the weak aggregation ability of BDT-T-2T-DPP produces a smaller size of 10-30 nm. The BDT-T-DPP/bis-PDI-T-EG combination exhibits balanced hole/electron mobility of 0.022/0.016 cm(2)/(V s), whereas the BDT-O-DPP/bis-PDI-T-EG and the BDT-T-2T-DPP/bis-PDI-T-EG blend show a hole/electron mobility of 0.0011/0.0057 cm(2)/(V s) and 0.0016/0.11 cm(2)/(V s), respectively.