Hsing-Ju Wang

Highly concentrated MoS2 nanosheets in water achieved by thioglycolic acid as stabilizer and used as biomarkers

In this work, we reported the synthesis of water soluble MoS2 quantum dots from the monolayer nanosheets of MoS2, using thioglycolic acid (TGA) with a sonication method. The gaps between the MoS2 layers were enlarged by the stirring process. Meanwhile TGA molecules strongly binding to the defect sites of MoS2 would reduce the van der Waals force between the MoS2 layers through sonication. This led to the improved dispersion of MoS2 monolayers in water. The addition of TGA molecules not only exfoliated the bulk of MoS2, but also modified the surface of MoS2 with carboxylic acid groups. As a result, highly concentrated MoS2 nanosheets were produced in water. Subsequently, heavy metal-free MoS2 quantum dots with sustained fluorescence emission, which were fabricated from hydrothermal treatment of MoS2 monolayers, can be utilized as cell biomarkers.

Polythiophenes Comprising Conjugated Pendants for Polymer Solar Cells: A Review

Polythiophene (PT) is one of the widely used donor materials for solution-processable polymer solar cells (PSCs). Much progress in PT-based PSCs can be attributed to the design of novel PTs exhibiting intense and broad visible absorption with high charge carrier mobility to increase short-circuit current density (Jsc), along with low-lying highest occupied molecular orbital (HOMO) levels to achieve large open circuit voltage (Voc) values. A promising strategy to tailor the photophysical properties and energy levels via covalently attaching electron donor and acceptor pendants on PTs backbone has attracted much attention recently. The geometry, electron-donating capacity, and composition of conjugated pendants are supposed to be the crucial factors in adjusting the conformation, energy levels, and photovoltaic performance of PTs. This review will go over the most recent approaches that enable researchers to obtain in-depth information in the development of PTs comprising conjugated pendants for PSCs.

Novel polythiophene derivatives functionalized with conjugated side-chain pendants comprising triphenylamine/carbazole moieties for photovoltaic cell applications†

We synthesized a series of polythiophenes (PTs) featuring 2-ethylhexyl-substituted terthiophene (T) or quaterthiophene (BT) as the conjugated unit in the polymer backbone with pendant conjugated tert-butyl-substituted triphenylamine (tTPA)- or carbazole (tCz)-containing moieties as side chains, namely PTtTPA, PBTtTPA, PTtCz and PBTtCz. Incorporating T and BT moieties into the polymer backbone and attaching tTPA or tCz units promoted efficient conjugation within the extended conjugated frameworks of the polymers, resulting in lower band-gap energies and red-shifting of the maximal UV-Vis absorption wavelength. The higher electron-donating ability of tTPA resulted in broader absorption bands and lower band-gap energies of PTtTPA and PBTtTPA as compared with PTtCz and PBTtCz. Incorporation of the T and BT moieties into the polymer backbone enhanced the compatibility of PT and the fullerene derivative by reducing the side-chain density of PT, thus providing sufficient free volume for efficient incorporation of [6,6]phenyl-C61-butyric acid methyl ester (PC61BM) into the polymer chains. Polymer solar cells (PSCs) were fabricated by spin-coating a blend of each PT with the fullerene derivative (PC61BM) as a composite film-type photoactive layer; PBTtTPA/PC61BM-based PSCs showed superior photovoltaic (PV) performance to PTtTPA/PC61BM-based PSCs in terms of conjugation and absorption band broadness. However, PBTtCz/PC61BM-based PSCs showed inferior PV performance to PTtCz/PC61BM-based PSCs. The lower HOMO level led to a higher open-circuit voltage (Voc; 0.74 V) and larger photo-energy conversion efficiency (η; 2.77%) of PTtCz/PC61BM-based PSCs.

Polythiophenes comprising conjugated pendants toward long-term air-stable inverted polymer solar cells with high open circuit voltages

A series of polythiophenes (PTs) functionalized with bulky conjugated side chains comprising tert-butyl substituted carbazole (tCz) as an electron donor pendant and bisbenzothiazolylvinyl (DBT) as an electron acceptor pendant were synthesized via Stille copolymerization for polymer solar cell (PSC) applications. We use the descriptors PTtCz, PT(tCz)0.9(DBT)0.1, PT(tCz)0.64(DBT)0.36, PT(tCz)0.45(DBT)0.55, and PTDBT to identify each of these conjugated polymers, with the names denoting the compositions of the bulky pendants. The tunable energy levels of the PTs were accomplished by incorporating both tCz as a donor pendant and DBT as an acceptor pendant, while retaining the low-lying HOMO levels (−5.26 to −5.39 eV). Furthermore, lower bandgaps were observed for the DBT-derived PTs because of stronger donor–π–acceptor characteristics and more efficient intramolecular charge transfer. Conventional PSCs were fabricated by spin-coating the blend of each PT and the fullerene derivative (PC71BM). The conventional PSC devices exhibited high open circuit voltages (Voc) of around 0.79–0.91 V. The power conversion efficiency (PCE) of the PSCs based on PTtCz : PC71BM (w/w = 1 : 2.5) reached 2.48% with a Voc of 0.91 V, short circuit current (Jsc) of 6.58 (mA cm−2) and fill factor (FF) of 41% under the illumination of AM1.5, 100 mW cm−2. Furthermore, a PTtCz/PC71BM-based inverted PSC with ZnOx and MoO3 as an electron extraction layer and a hole extraction layer respectively was capable of retaining ca. 80% of its original efficiency after storage under ambient conditions (without encapsulation) for 1032 h, according to the ISOS-D-1 shelf protocol. The highly durable inverted PSC accompanied by a large Voc value was achieved for the PT-type polymers.

Enhanced photovoltaic performance of inverted polymer solar cells by incorporating graphene nanosheet/AgNPs nanohybrids

A linear-dendritic block copolymer (LDBC) functionalized exfoliated graphene nanosheets (XGS)/silver nanoparticles (AgNPs) was prepared for using as the interfacial layer between the zinc oxide (ZnO) based electron-selective layer and poly(3-hexylthiophene) (P3HT)/fullerene derivative (PC61BM) blend based photoactive layer in an inverted polymer solar cell (PSC). The LDBCs were prepared by the respective addition reaction of a hydrophilic poly(oxyalkylene)amine with hydrophobic dendrons of various generations based on 4-isocyanate-4′-(3,3-dimethyl-2,4-dioxo-azetidine)-diphenylmethane (IDD). The dendrons having polyurea/malonamide functionalities were synthesized by using IDD as a building block. Moreover, the dendrons comprised not only hydrogen bond-rich malonamide linkages, but long alkyl chains at the peripheries as well. XGS were respectively grafted with these amphiphilic LDBCs to afford XGS-dendritic derivatives (XGS-G0.5, XGS-G1.5, and XGS-G2.5). Subsequently, a nanohybrid, XGS-G2.5/AgNPs was obtained through the reduction of Ag+ on the surface of LDBC modified XGS. The dendrons would serve as the effective templates for hosting AgNPs. By the incorporation of XGS-G2.5/AgNPs nanohybrid, it rendered the PSC an increased power conversion efficient (PCE) to 4.04%, a 19.5% improvement over a PCE of 3.38% for the bare inverted PSC, due to the localized surface plasmon resonance of AgNPs, and the improvement of compatibility and charge transfer capacity between ZnO based cathode and photoactive layer.

Determination of carbamazepine: a comparison of the differential pulse voltammetry (DPV) method and the immunoassay method in a clinical trial

We conducted a clinical trial to analyze human serum containing carbamazepine by using the differential pulse voltammetry (DPV) method with a glassy carbon electrode, and compared it with the fluorescence polarization immunoassay (FPIA). Thirty patients, who visited our hospital to have their serum carbamazepine level checked, were enrolled. Ten mL of venous blood was collected from each patient and analyzed by DPV and FPIA methods. The correlation between the carbamazepine concentrations determined by DPV and FPIA was good, with an RSQ of 0.998. The similarity of the results indicates that these two methods can be used interchangeably. The DPV method using a glassy carbon electrode may be a potential alternative method to determine the carbamazepine level in human serum.